Ammonites

James Hall, F. B. Meek, Descriptions of New Species of Fossils, from the Cretaceous Formations of Nebraska, with Observations upon Baculites ovatus and B. compressus, and the Progressive Development of the Septa in Baculites, Ammonites, and Scaphites, Memoirs of the American Academy of Arts and Sciences, New Series, Vol. 5, No. 2 (1855), pp. 379-411

@article{doi10230725058187,
    author = "Hall, James C. and Meek, F. B.",
    title = "Descriptions of New Species of Fossils, from the Cretaceous Formations of Nebraska, with Observations upon Baculites ovatus and B. compressus, and the Progressive Development of the Septa in Baculites, Ammonites, and Scaphites",
    year = "1855",
    journal = "Memoirs of the American Academy of Arts and Sciences",
    abstract = "James Hall, F. B. Meek, Descriptions of New Species of Fossils, from the Cretaceous Formations of Nebraska, with Observations upon Baculites ovatus and B. compressus, and the Progressive Development of the Septa in Baculites, Ammonites, and Scaphites, Memoirs of the American Academy of Arts and Sciences, New Series, Vol. 5, No. 2 (1855), pp. 379-411",
    url = "https://doi.org/10.2307/25058187",
    doi = "10.2307/25058187",
    openalex = "W2801867938"
}

In some recent papers dealing with Tithonian ammonites, the writer included zonal schemes of the higher Jurassic, up to what he considered the topmost horizon, namely the privasensis zone. The correlation of the Mediterranean ammonites with those of the “boreal province” or Pavlow's “Aquilonian” was also discussed. Since this author had recorded “Aquilonian” Craspedites and Garniericeras from the Speeton Clay and Spilsby Sandstone, the inquiry naturally led to a revision of the ammonites of the Neocomian of Yorkshire and Lincolnshire. A critical examination of the ammonite horizons at the Jurasso-Cretaceous border-line seemed specially invited because in our most recent textbooks Yorkshire strata obviously well up in the Cretaceous are still included in the Jurassic; and it was also deemed useful to link up the table of Tithonian ammonite zones, above referred to, with that of the Aptian, given by the writer in a paper on the “Ammonite Horizons of the Gault and Contiguous Formations”.

@article{doi101017s0016756800083588,
    author = "Spath, L. F.",
    title = "On the Ammonites of the Speeton Clay and the Subdivisions of the Neocomian",
    year = "1924",
    journal = "Geological Magazine",
    abstract = "In some recent papers dealing with Tithonian ammonites, the writer included zonal schemes of the higher Jurassic, up to what he considered the topmost horizon, namely the privasensis zone. The correlation of the Mediterranean ammonites with those of the “boreal province” or Pavlow's “Aquilonian” was also discussed. Since this author had recorded “Aquilonian” Craspedites and Garniericeras from the Speeton Clay and Spilsby Sandstone, the inquiry naturally led to a revision of the ammonites of the Neocomian of Yorkshire and Lincolnshire. A critical examination of the ammonite horizons at the Jurasso-Cretaceous border-line seemed specially invited because in our most recent textbooks Yorkshire strata obviously well up in the Cretaceous are still included in the Jurassic; and it was also deemed useful to link up the table of Tithonian ammonite zones, above referred to, with that of the Aptian, given by the writer in a paper on the “Ammonite Horizons of the Gault and Contiguous Formations”.",
    url = "https://doi.org/10.1017/s0016756800083588",
    doi = "10.1017/s0016756800083588",
    openalex = "W2123171648",
    references = "doi101017s0016756800202707"
}

Ammonites are comparatively common in the Cenomanian or Lower Chalk, become rarer in the Turonian or Middle Chalk, and are very scarce in the Upper Chalk. On a former occasion, when pointing out that while ammonites were unknown from the Micraster cor-testudinarium Chalk of England, they occurred in the same Chalk in the north of France, the writer was inclined to attribute this absence or scarcity to limited horizontal distribution of the ammonites. The possibility, however, of there being gaps in the Chalk succession, for example at the horizon of Actinocamax plena, at the Chalk-Rock, in and above the cor-anguinum zone, etc., cannot be denied. The zone of Micraster cor-anguinum is not quite so barren as the zone below, but the only ammonites hitherto known from it are doubtful examples, probably referable to Parapuzosia. One impression, on an oyster, of part of the ventral area of a large specimen, possibly of P. corbarica Grossouvre sp., was collected by Mr. Dibley in the London-Portland Pit at Northfleet, Kent, and Dr. Rowe recorded probably comparable Parapuzosia (“ammonites of the leptophyllus group”) from Dorset and Yorkshire.

@article{doi101017s0016756800083710,
    author = "Spath, L. F.",
    title = "On New Ammonites from the English Chalk",
    year = "1926",
    journal = "Geological Magazine",
    abstract = "Ammonites are comparatively common in the Cenomanian or Lower Chalk, become rarer in the Turonian or Middle Chalk, and are very scarce in the Upper Chalk. On a former occasion, when pointing out that while ammonites were unknown from the Micraster cor-testudinarium Chalk of England, they occurred in the same Chalk in the north of France, the writer was inclined to attribute this absence or scarcity to limited horizontal distribution of the ammonites. The possibility, however, of there being gaps in the Chalk succession, for example at the horizon of Actinocamax plena, at the Chalk-Rock, in and above the cor-anguinum zone, etc., cannot be denied. The zone of Micraster cor-anguinum is not quite so barren as the zone below, but the only ammonites hitherto known from it are doubtful examples, probably referable to Parapuzosia. One impression, on an oyster, of part of the ventral area of a large specimen, possibly of P. corbarica Grossouvre sp., was collected by Mr. Dibley in the London-Portland Pit at Northfleet, Kent, and Dr. Rowe recorded probably comparable Parapuzosia (“ammonites of the leptophyllus group”) from Dorset and Yorkshire.",
    url = "https://doi.org/10.1017/s0016756800083710",
    doi = "10.1017/s0016756800083710",
    openalex = "W2100676585"
}

@misc{brinkmann1929statistischbiostratigraphische2,
    author = "Brinkmann, R",
    title = "Statistischbiostratigraphische Untersuchungen an mitteljurassischen Ammoniten ber Artbegriff und Stammesenentwicklung",
    year = "1929",
    howpublished = "Gesell. Wiss. Gttingen, Abh., v. 13, no. 3, p. 1-249; math.-phys. Kl, n.ser",
    note = "talkorigins\_source = {true}; raw\_reference = {Brinkmann, R., 1929, Statistischbiostratigraphische Untersuchungen an mitteljurassischen Ammoniten ber Artbegriff und Stammesenentwicklung: Gesell. Wiss. Gttingen, Abh., v. 13, no. 3, p. 1-249; math.-phys. Kl, n.ser.}"
}

@misc{spath1938a11,
    author = "Spath, I. F",
    title = "A Catalogue of the Ammonites of the Liassic Family Liparoceratidae",
    year = "1938",
    howpublished = "London, British Museum (Natural History), 191 p",
    note = "talkorigins\_source = {true}; raw\_reference = {Spath, I. F., 1938, A Catalogue of the Ammonites of the Liassic Family Liparoceratidae: London, British Museum (Natural History), 191 p.}"
}

@article{doi103133pp206,
    author = "Cushman, Joseph A.",
    title = "Upper Cretaceous Foraminifera of the Gulf coastal region of the United States and adjacent areas",
    year = "1946",
    journal = "USGS professional paper",
    url = "https://doi.org/10.3133/pp206",
    doi = "10.3133/pp206",
    openalex = "W183657746"
}

@article{wright1949the12,
    author = "Wright, C. W. and Wright, E. V",
    title = "The Cretaceous ammonite genera Discohoplites and Hyphoplites Spath",
    year = "1949",
    journal = "Geological Society of London Quarterly Journal, v. 104, p. 477-497",
    note = "talkorigins\_source = {true}; raw\_reference = {Wright, C. W., and Wright, E. V., 1949, The Cretaceous ammonite genera Discohoplites and Hyphoplites Spath: Geological Society of London Quarterly Journal, v. 104, p. 477-497.}"
}

@article{doi10113000167606195162399mopato20co2,
    author = "Urey, Harold C. and Lowenstam, H. A. and Epstein, Samuel and McKinney, Curtis R.",
    title = "MEASUREMENT OF PALEOTEMPERATURES AND TEMPERATURES OF THE UPPER CRETACEOUS OF ENGLAND, DENMARK, AND THE SOUTHEASTERN UNITED STATES",
    year = "1951",
    journal = "Geological Society of America Bulletin",
    url = "https://doi.org/10.1130/0016-7606(1951)62[399:mopato]2.0.co;2",
    doi = "10.1130/0016-7606(1951)62[399:mopato]2.0.co;2",
    openalex = "W2044871718"
}

@article{doi101130001676061952631011cotcfo20co2,
    author = "Cobban, W. A. and Reeside, John B.",
    title = "CORRELATION OF THE CRETACEOUS FORMATIONS OF THE WESTERN INTERIOR OF THE UNITED STATES",
    year = "1952",
    journal = "Geological Society of America Bulletin",
    url = "https://doi.org/10.1130/0016-7606(1952)63[1011:cotcfo]2.0.co;2",
    doi = "10.1130/0016-7606(1952)63[1011:cotcfo]2.0.co;2",
    openalex = "W2041383534"
}

D R. W. J. ARKELL has recently published (1950) A Classification of the Jurassic Ammonites, primarily in connection with the forthcoming Treatise on Invertebrate Paleontology, sponsored in America by the Geological Society of America, the Paleontological Society and the Society of Economic Paleontologists and Mineralogists. The present paper is'the Cretaceous continuation of Arkell's and is published with the same intention as his, to elicit constructive criticism in advance of the completion of the section of the Treatise on Mesozoic Ammonoidea.

@article{openalexw2335826749,
    author = "Wright, C.W.",
    title = "A classification of the Cretaceous ammonites",
    year = "1952",
    journal = "Journal of Paleontology",
    abstract = "D R. W. J. ARKELL has recently published (1950) A Classification of the Jurassic Ammonites, primarily in connection with the forthcoming Treatise on Invertebrate Paleontology, sponsored in America by the Geological Society of America, the Paleontological Society and the Society of Economic Paleontologists and Mineralogists. The present paper is'the Cretaceous continuation of Arkell's and is published with the same intention as his, to elicit constructive criticism in advance of the completion of the section of the Treatise on Mesozoic Ammonoidea.",
    openalex = "W2335826749"
}

@misc{arkell1957mesozoic1,
    author = "Arkell, W. J. and Kummel, B. and Wright, C. W",
    title = "Mesozoic Ammonoidea, in Moore, R. C., ed., Treatise on Invertebrate Paleontology, Part L",
    year = "1957",
    howpublished = "p. L80- L465",
    note = "talkorigins\_source = {true}; raw\_reference = {Arkell, W. J., Kummel, B., and Wright, C. W., 1957, Mesozoic Ammonoidea, in Moore, R. C., ed., Treatise on Invertebrate Paleontology, Part L: p. L80- L465.}"
}

@misc{miller1957paleozoic10,
    author = "Miller, A. K. and Furnish, W. M. and Schindewolf, O. H",
    title = "Paleozoic Ammonodoidea",
    year = "1957",
    howpublished = "p. L11-L79, in Moore, R. C., ed., Treatise on Invertebrate Paleontology, Part L: p. L1-L490",
    note = "talkorigins\_source = {true}; raw\_reference = {Miller, A. K., Furnish, W. M., and Schindewolf, O. H., 1957, Paleozoic Ammonodoidea: p. L11-L79, in Moore, R. C., ed., Treatise on Invertebrate Paleontology, Part L: p. L1-L490.}"
}

@article{cobban1961the3,
    author = "Cobban, W. A",
    title = "The ammonite family Binneyitidae Reeside in the western interior of the United States",
    year = "1961",
    journal = "Journal of Paleontology, v. 35, p. 737-758",
    note = "talkorigins\_source = {true}; raw\_reference = {Cobban, W. A., 1961, The ammonite family Binneyitidae Reeside in the western interior of the United States: Journal of Paleontology, v. 35, p. 737-758.}"
}

The ammonite family Binneyitidae Reeside is represented in the Western Interior region of the United States by at least 3 species of Borissiakoceras, 5 species of Binneyites, and 1 species of a new genus, Johnsonites. The family is known only from the lower part of the Upper Cretaceous. Johnsonites, which is represented only by the genotype, occurs in the oldest of the Cenomanian zones of the Western Interior region. Borissiakoceras is found in the Cenomanian and in the lower part of the overlying Turonian. Binneyites has a range of about middle Turonian to lower Santonian. New species described are Johnsonites sulcatus, Borissiakoceras compressum, Binneyites carlilensis, B. nodosus, and B. rugosus.

@article{openalexw2125931334,
    author = "Cobban, W. A.",
    title = "THE AMMONITE FAMILY BINNEYITIDAE REESIDE IN THE WESTERN INTERIOR OF THE UNITED STATES",
    year = "1961",
    journal = "Journal of Paleontology",
    abstract = "The ammonite family Binneyitidae Reeside is represented in the Western Interior region of the United States by at least 3 species of Borissiakoceras, 5 species of Binneyites, and 1 species of a new genus, Johnsonites. The family is known only from the lower part of the Upper Cretaceous. Johnsonites, which is represented only by the genotype, occurs in the oldest of the Cenomanian zones of the Western Interior region. Borissiakoceras is found in the Cenomanian and in the lower part of the overlying Turonian. Binneyites has a range of about middle Turonian to lower Santonian. New species described are Johnsonites sulcatus, Borissiakoceras compressum, Binneyites carlilensis, B. nodosus, and B. rugosus.",
    url = "https://openalex.org/W2125931334",
    openalex = "W2125931334",
    references = "doi101130001676061952631011cotcfo20co2, doi1013063d93432e16b111d78645000102c1865d, doi103133pp186k, doi103133pp83, openalexw1483032662, openalexw1909835793, openalexw2335826749, openalexw2595223531, openalexw2735885194, openalexw3108005494"
}

@article{cobban1962baculites4,
    author = "Cobban, W. A",
    title = "Baculites from the lower part of the Pierre Shale and equivalent rocks in the western interior",
    year = "1962",
    journal = "Journal of Paleontology, v. 36, p. 704-718",
    note = "talkorigins\_source = {true}; raw\_reference = {Cobban, W. A., 1962, Baculites from the lower part of the Pierre Shale and equivalent rocks in the western interior: Journal of Paleontology, v. 36, p. 704-718.}"
}

@article{cobban1962new5,
    author = "Cobban, W. A",
    title = "New Baculites from the Bearpaw Shale and equivalent rocks of the western interior",
    year = "1962",
    journal = "Journal of Paleontology, v. 36, p. 126-135",
    note = "talkorigins\_source = {true}; raw\_reference = {Cobban, W. A., 1962, New Baculites from the Bearpaw Shale and equivalent rocks of the western interior: Journal of Paleontology, v. 36, p. 126-135.}"
}

@misc{cobban1964the6,
    author = "Cobban, W. A",
    title = "The Late Cretaceous cephalopod Haresiceras Reeside and its possible origin, 454-I of United States Geological Survey, Professional Paper",
    year = "1964",
    howpublished = "p. I1-I21",
    note = "talkorigins\_source = {true}; raw\_reference = {Cobban, W. A., 1964, The Late Cretaceous cephalopod Haresiceras Reeside and its possible origin, 454-I of United States Geological Survey, Professional Paper: p. I1-I21.}"
}

Ammonites from Nûgssuaq and Svartenhuk, belonging to the genera Hypophylloceras, Saghalinites, Pseudophyllites, Baculites, Diplomoceras, Scaphites, Clioscaphites, Haresiceras and Borissjakoceras, are described. Baculites and Scaphites are richly represented, and the material provides a basis for evaluating the subgenera Hoploscaphites and Discoscaphites. The ontogeny and the phylogeny of most of the genera are discussed and juvenile stages of Saghalinites and Scaphites described. Eleven new species and three new subspecies are introduced. The stratigraphical, palaeogeographical and palaeoecological aspeets of the ammonite assemblages are considered, and a discussion of sexual dimorphism in Scaphites is given. The presence of 12 biozones from the Upper Turonian?, Coniacian, Santonian, Campanian and Maastrichtian is demonstrated. The stratigraphical correlation of European and North American Upper Cretaceous deposits is discussed and the West Greenland zones are correlated with North American and European ammonite zones. All the Upper Turonian?-Santonian species have affinities with species endemic to the Western Interior of North America. One of the genera, Clioscaphites from the Santonian, occur only within that area. The Campanian scaphites and baculites are at first mostly like species from the Interior of North America, later, in the Upper Campanian, European affinities are more prominent. Haresiceras from the Lower Campanian is endemic to the Western Interior of North America. The Maastrichtian scaphites and baculites are closely related to endemic species from the Interior of North America, principally from the Fox Hills Formation of the type area. Hypophylloceras, Saghalinites and Pseudophyllites from the Campanian-Maastrichtian have Indo-Pacific relations and Diplomoceras may be related to European forms. The ammonites, together with the belemnites and inoceramids from the area, so far as they are identified, show that a sea-way to the north, through the Arctic Seas, conneeted this area with the Interior of North America from the Upper Turonian or Coniacian to the Maastrichtian. The area apparently was also connected with Europe by a sea-way during that part of the Upper Cretaceous. The occurrence of ammonites with Indo-Pacific affinities may further indicate the presence of a northern sea-way between the Pacific and the Arctic Seas during parts of the Campanian-Maastrichtian interval.Scaphites is given. The presence of 12 biozones from the Upper Turonian?, Coniacian, Santonian, Campanian and Maastrichtian is demonstrated. The stratigraphical correlation of European and North American Upper Cretaceous deposits is discussed and the West Greenland zones are correlated with North American and European ammonite zones. All the Upper Turonian?-Santonian species have affinities with species endemic to the Western Interior of North America. One of the genera, Clioscaphites from the Santonian, occur only within that area. The Campanian scaphites and baculites are at first mostly like species from the Interior of North America, later, in the Upper Campanian, European affinities are more prominent. Haresiceras from the Lower Campanian is endemic to the Western Interior of North America. The Maastrichtian scaphites and baculites are closely related to endemic species from the Interior of North America, principally from the Fox Hills Formation of the type area. Hypophylloceras, Saghalinites and Pseudophyllites from the Campanian-Maastrichtian have Indo-Pacific relations and Diplomoceras may be related to European forms. The ammonites, together with the belemnites and inoceramids from the area, so far as they are identified, show that a sea-way to the north, through the Arctic Seas, conneeted this area with the Interior of North America from the Upper Turonian or Coniacian to the Maastrichtian. The area apparently was also connected with Europe by a sea-way during that part of the Upper Cretaceous. The occurrence of ammonites with Indo-Pacific affinities may further indicate the presence of a northern sea-way between the Pacific and the Arctic Seas during parts of the Campanian-Maastrichtian interval.

@article{doi1034194bullgguv566590,
    author = "Birkelund, Tove",
    title = "Ammonites from the Upper Cretaceous of West Greenland",
    year = "1965",
    journal = "Grønlands Geologiske Undersøgelse Bulletin",
    abstract = "Ammonites from Nûgssuaq and Svartenhuk, belonging to the genera Hypophylloceras, Saghalinites, Pseudophyllites, Baculites, Diplomoceras, Scaphites, Clioscaphites, Haresiceras and Borissjakoceras, are described. Baculites and Scaphites are richly represented, and the material provides a basis for evaluating the subgenera Hoploscaphites and Discoscaphites. The ontogeny and the phylogeny of most of the genera are discussed and juvenile stages of Saghalinites and Scaphites described. Eleven new species and three new subspecies are introduced. The stratigraphical, palaeogeographical and palaeoecological aspeets of the ammonite assemblages are considered, and a discussion of sexual dimorphism in Scaphites is given. The presence of 12 biozones from the Upper Turonian?, Coniacian, Santonian, Campanian and Maastrichtian is demonstrated. The stratigraphical correlation of European and North American Upper Cretaceous deposits is discussed and the West Greenland zones are correlated with North American and European ammonite zones. All the Upper Turonian?-Santonian species have affinities with species endemic to the Western Interior of North America. One of the genera, Clioscaphites from the Santonian, occur only within that area. The Campanian scaphites and baculites are at first mostly like species from the Interior of North America, later, in the Upper Campanian, European affinities are more prominent. Haresiceras from the Lower Campanian is endemic to the Western Interior of North America. The Maastrichtian scaphites and baculites are closely related to endemic species from the Interior of North America, principally from the Fox Hills Formation of the type area. Hypophylloceras, Saghalinites and Pseudophyllites from the Campanian-Maastrichtian have Indo-Pacific relations and Diplomoceras may be related to European forms. The ammonites, together with the belemnites and inoceramids from the area, so far as they are identified, show that a sea-way to the north, through the Arctic Seas, conneeted this area with the Interior of North America from the Upper Turonian or Coniacian to the Maastrichtian. The area apparently was also connected with Europe by a sea-way during that part of the Upper Cretaceous. The occurrence of ammonites with Indo-Pacific affinities may further indicate the presence of a northern sea-way between the Pacific and the Arctic Seas during parts of the Campanian-Maastrichtian interval.Scaphites is given. The presence of 12 biozones from the Upper Turonian?, Coniacian, Santonian, Campanian and Maastrichtian is demonstrated. The stratigraphical correlation of European and North American Upper Cretaceous deposits is discussed and the West Greenland zones are correlated with North American and European ammonite zones. All the Upper Turonian?-Santonian species have affinities with species endemic to the Western Interior of North America. One of the genera, Clioscaphites from the Santonian, occur only within that area. The Campanian scaphites and baculites are at first mostly like species from the Interior of North America, later, in the Upper Campanian, European affinities are more prominent. Haresiceras from the Lower Campanian is endemic to the Western Interior of North America. The Maastrichtian scaphites and baculites are closely related to endemic species from the Interior of North America, principally from the Fox Hills Formation of the type area. Hypophylloceras, Saghalinites and Pseudophyllites from the Campanian-Maastrichtian have Indo-Pacific relations and Diplomoceras may be related to European forms. The ammonites, together with the belemnites and inoceramids from the area, so far as they are identified, show that a sea-way to the north, through the Arctic Seas, conneeted this area with the Interior of North America from the Upper Turonian or Coniacian to the Maastrichtian. The area apparently was also connected with Europe by a sea-way during that part of the Upper Cretaceous. The occurrence of ammonites with Indo-Pacific affinities may further indicate the presence of a northern sea-way between the Pacific and the Arctic Seas during parts of the Campanian-Maastrichtian interval.",
    url = "https://doi.org/10.34194/bullggu.v56.6590",
    doi = "10.34194/bullggu.v56.6590",
    openalex = "W640942546",
    references = "doi101130001676061952631011cotcfo20co2, doi101130mem71p1, doi101144gsljgs1940096010414, doi1013060bda5c3f16bd11d78645000102c1865d, doi1013063d93432e16b111d78645000102c1865d, doi1023071786846, doi1023072421322, doi103133pp151, doi105962bhltitle169047, doi105962bhltitle52405, openalexw2284373959, openalexw2595223531, openalexw2797845562, openalexw2945186736, openalexw638733414"
}

@article{erben1966ber8,
    author = "Erben, H. K",
    title = "ber den Ursprung der Ammonoidea",
    year = "1966",
    journal = "Biological Reviews, v. 41, p. 641-658",
    note = "talkorigins\_source = {true}; raw\_reference = {Erben, H. K., 1966, ber den Ursprung der Ammonoidea: Biological Reviews, v. 41, p. 641-658.}"
}

@misc{cobban1969the,
    author = "Cobban, William Aubrey",
    title = "The Late Cretaceous ammonites Scaphites leei Reeside and Scaphites hippocrepis (DeKay) in the western interior of the United States",
    year = "1969",
    booktitle = "Professional Paper",
    url = "https://doi.org/10.3133/pp619",
    doi = "10.3133/pp619",
    openalex = "W169721100",
    references = "doi101098rstb19550010, doi101130mem24, doi101130mem95p1, doi1034194bullgguv566590, doi105281zenodo16219869, doi105281zenodo16448613, doi105962bhltitle19929, openalexw1934811342, openalexw2768082911, openalexw656711665, openalexw657396478"
}

@misc{cobban1969the7,
    author = "Cobban, W. A",
    title = "The Late Cretaceous ammonites Scaphites leei Reeside and Scaphites hippocrepis (DeKay) in the western interior of the United States, 619 of United States Geological Survey, Professional Paper",
    year = "1969",
    howpublished = "p. 1-29",
    note = "talkorigins\_source = {true}; raw\_reference = {Cobban, W. A., 1969, The Late Cretaceous ammonites Scaphites leei Reeside and Scaphites hippocrepis (DeKay) in the western interior of the United States, 619 of United States Geological Survey, Professional Paper: p. 1-29.}"
}

Scaphites led Reeside and 8. hippocrepis (DeKay) are closely related ammonites found at many localities in Montana, Wyoming, South Dakota, Colorado, Utah, and New Mexico. Both species have been found in Texas, and S. hippocrepis occurs also in Alabama, Georgia, Maryland, Delaware, and New Jersey, as well as in several countries in Europe and Africa.

@article{doi103133pp619,
    author = "Cobban, W. A.",
    title = "The Late Cretaceous ammonites Scaphites leei Reeside and Scaphites hippocrepis (DeKay) in the western interior of the United States",
    year = "1969",
    journal = "USGS professional paper",
    abstract = "Scaphites led Reeside and 8. hippocrepis (DeKay) are closely related ammonites found at many localities in Montana, Wyoming, South Dakota, Colorado, Utah, and New Mexico. Both species have been found in Texas, and S. hippocrepis occurs also in Alabama, Georgia, Maryland, Delaware, and New Jersey, as well as in several countries in Europe and Africa.",
    url = "https://doi.org/10.3133/pp619",
    doi = "10.3133/pp619",
    openalex = "W169721100",
    references = "doi101098rstb19550010, doi101130mem24, doi101130mem95p1, doi1034194bullgguv566590, doi105281zenodo16219869, doi105281zenodo16448613, openalexw1934811342, openalexw2768082911, openalexw656711665, openalexw657396478"
}

Abstract Detailed correlation of electric-log resistivity patterns that result from variations in bentonite content of marine shale and siltstone reveals the presence of inclined time-stratigraphic units within the post-Turonian, marine Late Cretaceous section of Wyoming. Similar units have been recognized in rocks of the Permo-Pennsylvanian of Texas, the Devonian of Alberta, and the Mississippian of Illinois, and are attributed to submarine depositional topography. This interpretation, applied to the Late Cretaceous section of Wyoming, divides the epicontinental marine section into three major environments: shelf, slope, and basin. The inclined time-stratigraphic units were deposited on the slope, whereas thinner, more flat-lying units were deposited on the shelf and in the basin. Three examples demonstrate the wide areal distribution and the almost continuous presence of significant submarine topography in at least part of Wyoming during post-Turonian Late Cretaceous time. The first example, from the lower Cody Shale of the southeastern Big Horn basin, is used to introduce the concepts involved and methods of correlation and mapping. The second example, from the Niobrara Formation and the lower Pierre Shale of the southeastern Powder River basin, is used to illustrate the complexities that can result from multiple sequences of progradation. The third example, the regressive part of the Lewis Shale of the Washakie and Red Desert basins, includes thick sandstone bodies. For each example, the areas assigned to the shelf, slope, and basin environments are determined from isopach maps of time-stratigraphic units within each section. This type of analysis is useful in solving problems of paleogeography and paleoecology. In the Upper Cretaceous of Wyoming, analysis indicates previously unrecognized complexities in the basin-filling process and the resulting sequence of units. The areal distribution of the three environments, the lithologic characteristics of the rocks, and the volume of sediment deposited in each environment are functions of the balance between rate of subsidence and sediment supply. The lower Pierre Shale and the Niobrara Formation of the Powder River basin are examples of the “wide-shelf” configuration, in which subsidence is relatively slow, progradation is rapid, and sand is largely confined to the shelf. The regressive Lewis Shale of the Washakie and Red Desert basins illustrates the complex relations between a “narrow shelf”-delta sequence (Lewis Shale) and a barrier island-lagoon sequence (Fox Hills Sandstone and Lance Formation). The submarine topography within a basin at a particular time in the sequence of deposition (the relief between the shelf edge and the basin, and the water depth in the basin environment) can be estimated from the present thickness of slope deposits. These estimates require correction for compaction and for water depth at the outer edge of the shelf. Such estimates indicate that at times the depth of water in areas of active sedimentation exceeded 2,000 ft. The Upper Cretaceous section of the Western Interior long has been considered a “textbook example” of shallow-water sedimentation. It has been studied by hundreds of geologists with varied interests and from different backgrounds, including the petroleum industry, the Geological Survey, and academic institutions. The section abounds with excellent time-stratigraphic correlations, and well control is more than adequate for detailed study in many areas. The fact that the relations described here could be overlooked under conditions such as these shows that they may have been missed in stratigraphic sections in other areas.

@article{doi1013065d25cbb316c111d78645000102c1865d,
    author = "Asquith, D. O.",
    title = "Depositional Topography and Major Marine Environments, Late Cretaceous, Wyoming",
    year = "1970",
    journal = "AAPG Bulletin",
    abstract = "Abstract Detailed correlation of electric-log resistivity patterns that result from variations in bentonite content of marine shale and siltstone reveals the presence of inclined time-stratigraphic units within the post-Turonian, marine Late Cretaceous section of Wyoming. Similar units have been recognized in rocks of the Permo-Pennsylvanian of Texas, the Devonian of Alberta, and the Mississippian of Illinois, and are attributed to submarine depositional topography. This interpretation, applied to the Late Cretaceous section of Wyoming, divides the epicontinental marine section into three major environments: shelf, slope, and basin. The inclined time-stratigraphic units were deposited on the slope, whereas thinner, more flat-lying units were deposited on the shelf and in the basin. Three examples demonstrate the wide areal distribution and the almost continuous presence of significant submarine topography in at least part of Wyoming during post-Turonian Late Cretaceous time. The first example, from the lower Cody Shale of the southeastern Big Horn basin, is used to introduce the concepts involved and methods of correlation and mapping. The second example, from the Niobrara Formation and the lower Pierre Shale of the southeastern Powder River basin, is used to illustrate the complexities that can result from multiple sequences of progradation. The third example, the regressive part of the Lewis Shale of the Washakie and Red Desert basins, includes thick sandstone bodies. For each example, the areas assigned to the shelf, slope, and basin environments are determined from isopach maps of time-stratigraphic units within each section. This type of analysis is useful in solving problems of paleogeography and paleoecology. In the Upper Cretaceous of Wyoming, analysis indicates previously unrecognized complexities in the basin-filling process and the resulting sequence of units. The areal distribution of the three environments, the lithologic characteristics of the rocks, and the volume of sediment deposited in each environment are functions of the balance between rate of subsidence and sediment supply. The lower Pierre Shale and the Niobrara Formation of the Powder River basin are examples of the “wide-shelf” configuration, in which subsidence is relatively slow, progradation is rapid, and sand is largely confined to the shelf. The regressive Lewis Shale of the Washakie and Red Desert basins illustrates the complex relations between a “narrow shelf”-delta sequence (Lewis Shale) and a barrier island-lagoon sequence (Fox Hills Sandstone and Lance Formation). The submarine topography within a basin at a particular time in the sequence of deposition (the relief between the shelf edge and the basin, and the water depth in the basin environment) can be estimated from the present thickness of slope deposits. These estimates require correction for compaction and for water depth at the outer edge of the shelf. Such estimates indicate that at times the depth of water in areas of active sedimentation exceeded 2,000 ft. The Upper Cretaceous section of the Western Interior long has been considered a “textbook example” of shallow-water sedimentation. It has been studied by hundreds of geologists with varied interests and from different backgrounds, including the petroleum industry, the Geological Survey, and academic institutions. The section abounds with excellent time-stratigraphic correlations, and well control is more than adequate for detailed study in many areas. The fact that the relations described here could be overlooked under conditions such as these shows that they may have been missed in stratigraphic sections in other areas.",
    url = "https://doi.org/10.1306/5d25cbb3-16c1-11d7-8645000102c1865d",
    doi = "10.1306/5d25cbb3-16c1-11d7-8645000102c1865d",
    openalex = "W2108407536",
    references = "doi101029jz069i020p04257, doi101130001676061951621tceoda20co2, doi101130001676061952631011cotcfo20co2, doi1013060bda5b8816bd11d78645000102c1865d, doi1013060bda5c9f16bd11d78645000102c1865d, doi1013060bda5f6f16bd11d78645000102c1865d, doi1013063d93436d16b111d78645000102c1865d, doi1013065d25b71316c111d78645000102c1865d, doi1013065d25c27f16c111d78645000102c1865d, olivers1965depositional"
}

@misc{house1970on9,
    author = "House, M. R",
    title = "On the origin of the clymenid ammonoids",
    year = "1970",
    howpublished = "Palaeontology, v. 13, p. 664-676",
    note = "talkorigins\_source = {true}; raw\_reference = {House, M. R., 1970, On the origin of the clymenid ammonoids: Palaeontology, v. 13, p. 664-676.}"
}

@misc{cobban1971new,
    author = "Cobban, William Aubrey",
    title = "New and little-known ammonites from the Upper Cretaceous (Cenomanian and Turonian) of the western interior of the United States",
    year = "1971",
    booktitle = "Professional Paper",
    url = "https://doi.org/10.3133/pp699",
    doi = "10.3133/pp699",
    openalex = "W1523939513",
    references = "doi1013063d93432e16b111d78645000102c1865d, doi1051091524329, doi105962bhltitle38908, doi105962bhltitle61419, openalexw2306538690, openalexw2595223531"
}

@article{doi1010160031018278900184,
    author = "Rawson, Peter F.",
    title = "The cretaceous system in the Western interior of North America",
    year = "1978",
    journal = "Palaeogeography Palaeoclimatology Palaeoecology",
    url = "https://doi.org/10.1016/0031-0182(78)90018-4",
    doi = "10.1016/0031-0182(78)90018-4",
    openalex = "W342436617"
}

ABSTRACT Two-dimensional modeling of loading during the formation of the Idaho-Wyoming thrust belt shows that regional isostatic compensation by flexure of an elastic lithosphere is sufficient to control the formation of a foreland basin. The flexural rigidity of the lithosphere is inferred to have been approximately 1023 Nm (1030 dyne cm), on the basis of palinspastic comparison of predicted downwarping, due to the thrust plate loads, to the shape of the sedimentary wedge on the west side of the Cretaceous Western Interior seaway. Erosion of part of the uplifted thrust plates redistributed the load, depositing it farther to the east, thereby causing subsidence over a much wider area than could have been accomplished only by the loading by thrust plates. Paleotopography after major Cretaceous thrust events was calculated. The resulting mountainous terrain, gentle alluvial plain, and flat sea floor correspond well with the topography of the modern foreland thrust belt and basin system in the Andes of South America and to paleogeographic reconstructions in the western United States thrust belt. Topography is controlled by the subsurface geometry of the thrust faults, particularly the positions of ramp zones, and by isostatic subsidence.

@article{doi10130603b599f416d111d78645000102c1865d,
    author = "Jordan, Teresa E.",
    title = "Thrust Loads and Foreland Basin Evolution, Cretaceous, Western United States",
    year = "1981",
    journal = "AAPG Bulletin",
    abstract = "ABSTRACT Two-dimensional modeling of loading during the formation of the Idaho-Wyoming thrust belt shows that regional isostatic compensation by flexure of an elastic lithosphere is sufficient to control the formation of a foreland basin. The flexural rigidity of the lithosphere is inferred to have been approximately 1023 Nm (1030 dyne cm), on the basis of palinspastic comparison of predicted downwarping, due to the thrust plate loads, to the shape of the sedimentary wedge on the west side of the Cretaceous Western Interior seaway. Erosion of part of the uplifted thrust plates redistributed the load, depositing it farther to the east, thereby causing subsidence over a much wider area than could have been accomplished only by the loading by thrust plates. Paleotopography after major Cretaceous thrust events was calculated. The resulting mountainous terrain, gentle alluvial plain, and flat sea floor correspond well with the topography of the modern foreland thrust belt and basin system in the Andes of South America and to paleogeographic reconstructions in the western United States thrust belt. Topography is controlled by the subsurface geometry of the thrust faults, particularly the positions of ramp zones, and by isostatic subsidence.",
    url = "https://doi.org/10.1306/03b599f4-16d1-11d7-8645000102c1865d",
    doi = "10.1306/03b599f4-16d1-11d7-8645000102c1865d",
    openalex = "W2083997111",
    references = "doi1010160012821x78900365, doi1010160040195176900044, doi101029jb075i020p03941, doi101029jb083ib12p05989, doi101111j1365246x1981tb02715x, doi101130001676061978891389rbeass20co2, doi1013065d25cbb316c111d78645000102c1865d, doi101306a663386e16c011d78645000102c1865d, doi101306st6398c16, doi102110pec74220001, openalexw2474977981, openalexw586757543"
}

Calcareous nannofossil assemblages recovered from a long, continuous section ranging in age from Callovian to middle Albian have been described from Deep Sea Drilling Project Site 534 in the Blake-Bahama Basin in the western North Atlantic. Coccolith preservation, combined with backtracking of Site 534, indicates that the CCD (calcite compensation depth) deepened from about 2.5 km in the middle Callovian to 3.6 km in the Tithonian; the CCD remained deep (around 4 km) during the Early Cretaceous and shallowed abruptly in the Aptian to a depth of 3 km. A revised zonation for the Jurassic is used to subdivide the middle Callovian to Tithonian interval into five zones and subzones. Previously published zones for the Lower Cretaceous are used, but the ranges of important marker species are more fully documented. Lower Cretaceous coccolith and dinoflagellate zones are correlated. The relationship of calcareous nannofossil zones with magnetostratigraphic units and stages is shown. Differences in Jurassic oceanic and epicontinental coccolith assemblages are attributed mainly to preservational differences and minor paleoecological effects. Two new species, Cruciplacolithus furtivus n. sp. and Polypodorhabdus harisonii Medd n. sp., are described, and several new combinations are introduced.

@incollection{doi102973dsdpproc761251983,
    author = "Roth, Peter H",
    title = "Jurassic and Lower Cretaceous Calcareous Nannofossils in the Western North Atlantic (Site 534): Biostratigraphy, Preservation, and Some Observations on Biogeography and Paleoceanography",
    year = "1983",
    booktitle = "U.S. Government Printing Office eBooks",
    abstract = "Calcareous nannofossil assemblages recovered from a long, continuous section ranging in age from Callovian to middle Albian have been described from Deep Sea Drilling Project Site 534 in the Blake-Bahama Basin in the western North Atlantic. Coccolith preservation, combined with backtracking of Site 534, indicates that the CCD (calcite compensation depth) deepened from about 2.5 km in the middle Callovian to 3.6 km in the Tithonian; the CCD remained deep (around 4 km) during the Early Cretaceous and shallowed abruptly in the Aptian to a depth of 3 km. A revised zonation for the Jurassic is used to subdivide the middle Callovian to Tithonian interval into five zones and subzones. Previously published zones for the Lower Cretaceous are used, but the ranges of important marker species are more fully documented. Lower Cretaceous coccolith and dinoflagellate zones are correlated. The relationship of calcareous nannofossil zones with magnetostratigraphic units and stages is shown. Differences in Jurassic oceanic and epicontinental coccolith assemblages are attributed mainly to preservational differences and minor paleoecological effects. Two new species, Cruciplacolithus furtivus n. sp. and Polypodorhabdus harisonii Medd n. sp., are described, and several new combinations are introduced.",
    url = "https://doi.org/10.2973/dsdp.proc.76.125.1983",
    doi = "10.2973/dsdp.proc.76.125.1983",
    openalex = "W2503778394",
    references = "doi102973dsdpproc431171979"
}

The Western Interior of the United States contains an important sequence of middle Cenomanian-late Turonian ammonites. Ammonites from the northern part of the Western Interior are mostly North Temperate forms, whereas those from the southern part are a mixture of Tethyan and North Temperate forms. The ammonite succession in the southern part can be more finely zoned than that of the northern part, and offers better possibilities for international correlation. In the zonation, the boundary between the middle and upper Cenomanian is placed at the top of the zone of Plesiacanthoceras aff. P. wyomingense. The top of the Cenomanian is drawn at the top of the zone of Neocardioceras juddii as recommended in a 1981 study by C. W. Wright and W. J. Kennedy. However, Mammites nodosoides, which occurs three zones higher, is usually regarded in Europe as basal Turonian, although Wright and Kennedy have now recognized a zone of Watinoceras coloradoense at the base, which lies below the zone of Mammites nodosoides. In the Western Interior, W. coloradoense is restricted to the zone of Vascoceras (Greenhornoceras) birchbyi, which is separated from the zone of Neocardioceras juddii by a zone of Pseudaspidoceras flexuosum. Inasmuch as the ammonites in the latter zone are closely related to those in the zone of V. birchbyi, a Turonian assignment seems best for the zone of P. flexuosum. Collignoniceras woollgari, which is widely distributed in Europe, Asia, and North America, is usually regarded as middle Turonian in a threefold division and late Turonian in a twofold division. I consider the species to mark the base of the middle Turonian. Where to place the top of the middle Turonian, however, is a problem. Inasmuch as the best fauna! break is at the top of the zone of Prionocyclus hyatti, that is where the boundary is placed in this report. Inoceramids in the zone of P. hyatti are characterized by forms having a radial depression like the middle Turonian Inoceramus hobetsensis of Japan. The top of the Turonian is designated here at the top of the zone of Prionocyclus quadratus. Fossils of this zone include inoceramids of the fiegei-dresdensis group, which in Europe have been considered either very late Turonian in age or very early Coniacian. Prionocyclus quadratus is the youngest species of a lineage of prionocyclids. This species is succeeded by Forresteria (Solgerites) of Coniacian Age.

@article{cobban1984midcretaceous,
    author = "Cobban, William A.",
    title = "Mid-Cretaceous ammonite zones, Western Interior, United States",
    year = "1984",
    journal = "Bulletin of the Geological Society of Denmark",
    abstract = "The Western Interior of the United States contains an important sequence of middle Cenomanian-late Turonian ammonites. Ammonites from the northern part of the Western Interior are mostly North Temperate forms, whereas those from the southern part are a mixture of Tethyan and North Temperate forms. The ammonite succession in the southern part can be more finely zoned than that of the northern part, and offers better possibilities for international correlation. In the zonation, the boundary between the middle and upper Cenomanian is placed at the top of the zone of Plesiacanthoceras aff. P. wyomingense. The top of the Cenomanian is drawn at the top of the zone of Neocardioceras juddii as recommended in a 1981 study by C. W. Wright and W. J. Kennedy. However, Mammites nodosoides, which occurs three zones higher, is usually regarded in Europe as basal Turonian, although Wright and Kennedy have now recognized a zone of Watinoceras coloradoense at the base, which lies below the zone of Mammites nodosoides. In the Western Interior, W. coloradoense is restricted to the zone of Vascoceras (Greenhornoceras) birchbyi, which is separated from the zone of Neocardioceras juddii by a zone of Pseudaspidoceras flexuosum. Inasmuch as the ammonites in the latter zone are closely related to those in the zone of V. birchbyi, a Turonian assignment seems best for the zone of P. flexuosum. Collignoniceras woollgari, which is widely distributed in Europe, Asia, and North America, is usually regarded as middle Turonian in a threefold division and late Turonian in a twofold division. I consider the species to mark the base of the middle Turonian. Where to place the top of the middle Turonian, however, is a problem. Inasmuch as the best fauna! break is at the top of the zone of Prionocyclus hyatti, that is where the boundary is placed in this report. Inoceramids in the zone of P. hyatti are characterized by forms having a radial depression like the middle Turonian Inoceramus hobetsensis of Japan. The top of the Turonian is designated here at the top of the zone of Prionocyclus quadratus. Fossils of this zone include inoceramids of the fiegei-dresdensis group, which in Europe have been considered either very late Turonian in age or very early Coniacian. Prionocyclus quadratus is the youngest species of a lineage of prionocyclids. This species is succeeded by Forresteria (Solgerites) of Coniacian Age.",
    url = "https://doi.org/10.37570/bgsd-1984-33-06",
    doi = "10.37570/bgsd-1984-33-06",
    pages = "71-89",
    volume = "33"
}

David L. Dilcher, Peter R. Crane, Archaenthus: An Early Angiosperm From the Cenomanian of the Western Interior of North America, Annals of the Missouri Botanical Garden, Vol. 71, No. 2, Historical Perspectives of Angiosperm Evolution (1984), pp. 351-383

@article{doi1023072399030,
    author = "Dilcher, David L. and Crane, Peter R.",
    title = "Archaenthus: An Early Angiosperm From the Cenomanian of the Western Interior of North America",
    year = "1984",
    journal = "Annals of the Missouri Botanical Garden",
    abstract = "David L. Dilcher, Peter R. Crane, Archaenthus: An Early Angiosperm From the Cenomanian of the Western Interior of North America, Annals of the Missouri Botanical Garden, Vol. 71, No. 2, Historical Perspectives of Angiosperm Evolution (1984), pp. 351-383",
    url = "https://doi.org/10.2307/2399030",
    doi = "10.2307/2399030",
    openalex = "W2097016244",
    references = "crossref1977mesozoic, doi101007bf02806171, doi101007bf02860849, doi1010160012825277901362, doi101093oxfordjournalsaoba083225, doi101111j109583391980tb01661x, doi1023071218350, doi1023071222465, doi1023071292633, doi1023072258301, doi1023072806386, openalexw2474977981, openalexw2597185021"
}

The Western Interior of the United States contains an important sequence of middle Cenomanian-late Turonian ammonites. Ammonites from the northern part of the Western Interior are mostly North Temperate forms, whereas those from the southern part are a mixture of Tethyan and North Temperate forms. The ammonite succession in the southern part can be more finely zoned than that of the northern part, and offers better possibilities for international correlation. In the zonation, the boundary between the middle and upper Cenomanian is placed at the top of the zone of Plesiacanthoceras aff. P. wyomingense. The top of the Cenomanian is drawn at the top of the zone of Neocardioceras juddii as recommended in a 1981 study by C. W. Wright and W. J. Kennedy. However, Mammites nodosoides, which occurs three zones higher, is usually regarded in Europe as basal Turonian, although Wright and Kennedy have now recognized a zone of Watinoceras coloradoense at the base, which lies below the zone of Mammites nodosoides. In the Western Interior, W. coloradoense is restricted to the zone of Vascoceras (Greenhornoceras) birchbyi, which is separated from the zone of Neocardioceras juddii by a zone of Pseudaspidoceras flexuosum. Inasmuch as the ammonites in the latter zone are closely related to those in the zone of V. birchbyi, a Turonian assignment seems best for the zone of P. flexuosum. Collignoniceras woollgari, which is widely distributed in Europe, Asia, and North America, is usually regarded as middle Turonian in a threefold division and late Turonian in a twofold division. I consider the species to mark the base of the middle Turonian. Where to place the top of the middle Turonian, however, is a problem. Inasmuch as the best fauna! break is at the top of the zone of Prionocyclus hyatti, that is where the boundary is placed in this report. Inoceramids in the zone of P. hyatti are characterized by forms having a radial depression like the middle Turonian Inoceramus hobetsensis of Japan. The top of the Turonian is designated here at the top of the zone of Prionocyclus quadratus. Fossils of this zone include inoceramids of the fiegei-dresdensis group, which in Europe have been considered either very late Turonian in age or very early Coniacian. Prionocyclus quadratus is the youngest species of a lineage of prionocyclids. This species is succeeded by Forresteria (Solgerites) of Coniacian Age.

@article{doi1037570bgsd19843306,
    author = "Cobban, W. A.",
    title = "Mid-Cretaceous ammonite zones, Western Interior, United States",
    year = "1984",
    journal = "Bulletin of the Geological Society of Denmark",
    abstract = "The Western Interior of the United States contains an important sequence of middle Cenomanian-late Turonian ammonites. Ammonites from the northern part of the Western Interior are mostly North Temperate forms, whereas those from the southern part are a mixture of Tethyan and North Temperate forms. The ammonite succession in the southern part can be more finely zoned than that of the northern part, and offers better possibilities for international correlation. In the zonation, the boundary between the middle and upper Cenomanian is placed at the top of the zone of Plesiacanthoceras aff. P. wyomingense. The top of the Cenomanian is drawn at the top of the zone of Neocardioceras juddii as recommended in a 1981 study by C. W. Wright and W. J. Kennedy. However, Mammites nodosoides, which occurs three zones higher, is usually regarded in Europe as basal Turonian, although Wright and Kennedy have now recognized a zone of Watinoceras coloradoense at the base, which lies below the zone of Mammites nodosoides. In the Western Interior, W. coloradoense is restricted to the zone of Vascoceras (Greenhornoceras) birchbyi, which is separated from the zone of Neocardioceras juddii by a zone of Pseudaspidoceras flexuosum. Inasmuch as the ammonites in the latter zone are closely related to those in the zone of V. birchbyi, a Turonian assignment seems best for the zone of P. flexuosum. Collignoniceras woollgari, which is widely distributed in Europe, Asia, and North America, is usually regarded as middle Turonian in a threefold division and late Turonian in a twofold division. I consider the species to mark the base of the middle Turonian. Where to place the top of the middle Turonian, however, is a problem. Inasmuch as the best fauna! break is at the top of the zone of Prionocyclus hyatti, that is where the boundary is placed in this report. Inoceramids in the zone of P. hyatti are characterized by forms having a radial depression like the middle Turonian Inoceramus hobetsensis of Japan. The top of the Turonian is designated here at the top of the zone of Prionocyclus quadratus. Fossils of this zone include inoceramids of the fiegei-dresdensis group, which in Europe have been considered either very late Turonian in age or very early Coniacian. Prionocyclus quadratus is the youngest species of a lineage of prionocyclids. This species is succeeded by Forresteria (Solgerites) of Coniacian Age.",
    url = "https://doi.org/10.37570/bgsd-1984-33-06",
    doi = "10.37570/bgsd-1984-33-06",
    openalex = "W2292867823"
}

@misc{cobban1987some,
    author = "Cobban, W.A.",
    title = "Some middle Cenomanian (Upper Cretaceous) acanthoceratid ammonites from the Western Interior of the United States",
    year = "1987",
    booktitle = "Professional Paper",
    url = "https://doi.org/10.3133/pp1445",
    doi = "10.3133/pp1445",
    openalex = "W120241039",
    references = "doi101017cbo9781316146309, doi101130gsab4969, doi101130mem149px, doi101130mem39, doi1013063d93432e16b111d78645000102c1865d, doi105479si00963801341611259, doi105962bhltitle38908, openalexw1483032662, openalexw1602415569, openalexw2460763456"
}

@article{doi1010160031018289900230,
    author = "Eicher, Don L. and Diner, Richard",
    title = "Origin of the cretaceous bridge creek cycles in the western interior, United States",
    year = "1989",
    journal = "Palaeogeography Palaeoclimatology Palaeoecology",
    url = "https://doi.org/10.1016/0031-0182(89)90023-0",
    doi = "10.1016/0031-0182(89)90023-0",
    openalex = "W2068328193",
    references = "openalexw1836508436, openalexw2597185021"
}

Pteroscaphites are small, rare species of scaphitid ammonites from the Upper Cretaceous (Turonian-Santonian) of the Western Interior of North America. Their evolution appears to parallel that of the larger species of Scaphites or Clioscaphites, with which they co-occur. To investigate this evolutionary pattern, I constructed a phylogeny of all these species based on their distribution of shared derived characters including ornamentation, ammonitella size, whorl shape, umbilical diameter, sutures, number of whorls, adult size, shape of the adult body chamber, and apertural modifications. This analysis revealed numerous instances of congruence in the preadult morphology of the pteroscaphites and that of the co-occurring scaphites or clioscaphites. However, there is a marked divergence at maturity. Adult pteroscaphites are uniformly small (2.5 postembryonic whorls in their phragmocone) and develop apertural projections. The scaphites and clioscaphites exhibit a number of morphological changes at approximately the same whorl number, but secrete as many as two more whorls in their phragmocone before forming a mature body chamber with a relatively unmodified aperture. Both groups display sexual dimorphism. The process of progenesis may explain this conflicting pattern of congruence prior to maturity and divergence at maturity. Adult pteroscaphites are not mature replicas of the juvenile shells of the larger scaphites or clioscaphites, because maturation produces its own set of morphological modifications. Nevertheless, such features as the apertural projections on adult pteroscaphites may be interpreted as extrapolations of juvenile patterns of growth into maturity. The repeated associations of pteroscaphites with scaphites or clioscaphites in the Upper Cretaceous suggest that progenesis was iterative and may have represented an optional developmental pathway common to all of these species.

@article{doi101017s0094837300009301,
    author = "Landman, Neil H.",
    title = "Iterative progenesis in Upper Cretaceous ammonites",
    year = "1989",
    journal = "Paleobiology",
    abstract = "Pteroscaphites are small, rare species of scaphitid ammonites from the Upper Cretaceous (Turonian-Santonian) of the Western Interior of North America. Their evolution appears to parallel that of the larger species of Scaphites or Clioscaphites, with which they co-occur. To investigate this evolutionary pattern, I constructed a phylogeny of all these species based on their distribution of shared derived characters including ornamentation, ammonitella size, whorl shape, umbilical diameter, sutures, number of whorls, adult size, shape of the adult body chamber, and apertural modifications. This analysis revealed numerous instances of congruence in the preadult morphology of the pteroscaphites and that of the co-occurring scaphites or clioscaphites. However, there is a marked divergence at maturity. Adult pteroscaphites are uniformly small (2.5 postembryonic whorls in their phragmocone) and develop apertural projections. The scaphites and clioscaphites exhibit a number of morphological changes at approximately the same whorl number, but secrete as many as two more whorls in their phragmocone before forming a mature body chamber with a relatively unmodified aperture. Both groups display sexual dimorphism. The process of progenesis may explain this conflicting pattern of congruence prior to maturity and divergence at maturity. Adult pteroscaphites are not mature replicas of the juvenile shells of the larger scaphites or clioscaphites, because maturation produces its own set of morphological modifications. Nevertheless, such features as the apertural projections on adult pteroscaphites may be interpreted as extrapolations of juvenile patterns of growth into maturity. The repeated associations of pteroscaphites with scaphites or clioscaphites in the Upper Cretaceous suggest that progenesis was iterative and may have represented an optional developmental pathway common to all of these species.",
    url = "https://doi.org/10.1017/s0094837300009301",
    doi = "10.1017/s0094837300009301",
    openalex = "W2491867408",
    references = "cobban1987some"
}

High-resolution stratigraphic analysis of 18 sections spanning the Cenomanian–Turonian Stage boundary in the western interior of the United States has allowed determination of the magnitude and pattern of molluscan extinction and disruption. Composite range data from all sections show that the faunal turnover across the stage boundary occurs in a series of narrow stratigraphic zones, defined by multiple first and last occurrences, separated by intervals displaying little or no taxonomic turnover. Two of the apparent extinction steps (bottom and top of the Neocardioceras juddii Zone) may be intercontinentally developed. The additional steps apparently reflect cyclic changes in water mass and substrate characteristics in the western interior basin produced in response to orbital forcing of climate. An interval (ca. 10-100 k.y. duration) of changing community structure and general biotic deterioration is found below each of the two potentially intercontinentally developed extinction steps. The most affected mollusks were those having intercontinental distributions (ammonites and inoceramid bivalves), suggesting that disruption of planktotrophic larval dispersal may have played a role in increasing extinction and speciation rates near the C–T boundary. The nekto-benthic ammonites were affected earlier and to a greater degree than the pelagic forms, implying progressive upward expansion of the oxygen minimum zone preceding the stage boundary.

@article{doi101017s0094837300009465,
    author = "Elder, William P.",
    title = "Molluscan extinction patterns across the Cenomanian-Turonian Stage boundary in the western interior of the United States",
    year = "1989",
    journal = "Paleobiology",
    abstract = "High-resolution stratigraphic analysis of 18 sections spanning the Cenomanian–Turonian Stage boundary in the western interior of the United States has allowed determination of the magnitude and pattern of molluscan extinction and disruption. Composite range data from all sections show that the faunal turnover across the stage boundary occurs in a series of narrow stratigraphic zones, defined by multiple first and last occurrences, separated by intervals displaying little or no taxonomic turnover. Two of the apparent extinction steps (bottom and top of the Neocardioceras juddii Zone) may be intercontinentally developed. The additional steps apparently reflect cyclic changes in water mass and substrate characteristics in the western interior basin produced in response to orbital forcing of climate. An interval (ca. 10-100 k.y. duration) of changing community structure and general biotic deterioration is found below each of the two potentially intercontinentally developed extinction steps. The most affected mollusks were those having intercontinental distributions (ammonites and inoceramid bivalves), suggesting that disruption of planktotrophic larval dispersal may have played a role in increasing extinction and speciation rates near the C–T boundary. The nekto-benthic ammonites were affected earlier and to a greater degree than the pelagic forms, implying progressive upward expansion of the oxygen minimum zone preceding the stage boundary.",
    url = "https://doi.org/10.1017/s0094837300009465",
    doi = "10.1017/s0094837300009465",
    openalex = "W1801969044",
    references = "cobban1984midcretaceous"
}

@article{doi101016003101829090110s,
    author = "Nicholls, Elizabeth L. and Russell, Anthony P.",
    title = "Paleobiogeography of the Cretaceous Western Interior Seaway of North America: the vertebrate evidence",
    year = "1990",
    journal = "Palaeogeography Palaeoclimatology Palaeoecology",
    url = "https://doi.org/10.1016/0031-0182(90)90110-s",
    doi = "10.1016/0031-0182(90)90110-s",
    openalex = "W2083843571",
    references = "cobban1969the, doi1010160031018278900184, doi101017s0094837300006254, doi101038scientificamerican047558, doi101130001676061952631011cotcfo20co2, doi101146annurevea05050177001535, doi103133pp392a, doi103133pp619, openalexw1572889853, openalexw2336741175, openalexw2597883917, openalexw568790138, openalexw575222456"
}

Abstract An upper Santonian fauna dominated by the curved baculitid Boehmoceras Riedel, 1931, occurs as phosphatic moulds in the Tombigbee Sand Member of the Eutaw Formation in Mississippi and Alabama, and also is reworked into the base of the Mooreville Chalk; a similar assemblage is present in the middle part of the Pen Formation of the Big Bend area, Texas. The assemblage is: Pseudoschloenbachia (Pseudoschloenbachia) mexicana (Renz, 1936), Placenticeras syrtale (Morton, 1834), Reginaites leei (Reeside, 1927a), Reginaites exilis sp. nov., Texanites (Texanites) sp. juv. cf. gallicus Collignon, 1948, Texanites (Plesiotexanites) shiloensis Young, 1963, Texanitinae incertae sedis, Hyphantoceras (?) amapondense (van Hoepen, 1921). Glyptoxoceras spp., Boehmoceras arculus (Morton, 1834) and Scaphites (Scaphites) leei Reeside, 1927a, form I. The assemblage is referred to the uppermost Santonian Texanites (Plesiotexanites) shiloensis zone of the Gulf Coast sequence. Common occurrence of Scaphites (S.) leei I and Reginaites leei suggest correlation with the Upper Santonian Desmoscaphites erdmanni zone of the U.S. Western Interior; common occurrence of Boehmoceras arculus (= B. loescheri of European authors) suggests correlation with the Marsupites–granulata zone at the top of the North German Santonian. These data strengthen intercontinental correlation of the Santonian–Campanian boundary sequence. They also provide a biostratigraphic link to a numerical age of 84.2±0.9 Ma from a bentonite at a slightly lower level in the Tombigbee Sand Member of the Eutaw Formation in Mississippi.

@article{doi101017s0016756800018355,
    author = "Kennedy, William J. and Cobban, W. A.",
    title = "Upper Cretaceous (upper Santonian) Boehmoceras fauna from the Gulf Coast region of the United States",
    year = "1991",
    journal = "Geological Magazine",
    abstract = "Abstract An upper Santonian fauna dominated by the curved baculitid Boehmoceras Riedel, 1931, occurs as phosphatic moulds in the Tombigbee Sand Member of the Eutaw Formation in Mississippi and Alabama, and also is reworked into the base of the Mooreville Chalk; a similar assemblage is present in the middle part of the Pen Formation of the Big Bend area, Texas. The assemblage is: Pseudoschloenbachia (Pseudoschloenbachia) mexicana (Renz, 1936), Placenticeras syrtale (Morton, 1834), Reginaites leei (Reeside, 1927a), Reginaites exilis sp. nov., Texanites (Texanites) sp. juv. cf. gallicus Collignon, 1948, Texanites (Plesiotexanites) shiloensis Young, 1963, Texanitinae incertae sedis, Hyphantoceras (?) amapondense (van Hoepen, 1921). Glyptoxoceras spp., Boehmoceras arculus (Morton, 1834) and Scaphites (Scaphites) leei Reeside, 1927a, form I. The assemblage is referred to the uppermost Santonian Texanites (Plesiotexanites) shiloensis zone of the Gulf Coast sequence. Common occurrence of Scaphites (S.) leei I and Reginaites leei suggest correlation with the Upper Santonian Desmoscaphites erdmanni zone of the U.S. Western Interior; common occurrence of Boehmoceras arculus (= B. loescheri of European authors) suggests correlation with the Marsupites–granulata zone at the top of the North German Santonian. These data strengthen intercontinental correlation of the Santonian–Campanian boundary sequence. They also provide a biostratigraphic link to a numerical age of 84.2±0.9 Ma from a bentonite at a slightly lower level in the Tombigbee Sand Member of the Eutaw Formation in Mississippi.",
    url = "https://doi.org/10.1017/s0016756800018355",
    doi = "10.1017/s0016756800018355",
    openalex = "W2076221239",
    references = "doi1013063d93302216b111d78645000102c1865d, doi103133pp151, openalexw2335826749"
}

Mytiloides hattini, a new species of inoceramid bivalve from the basal Turonian (Upper Cretaceous), is described and its stratigraphic importance discussed. This inoceramid is particularly significant because its first occurrence can be used as a marker for the base of the Turonian in strata that typically contain no ammonites and few other taxa. The lowest occurrence of Mytiloides hattini is characterized by abundant specimens over wide regions of the Western Interior of North America; this species also apparently occurs in the lowest Turonian strata of western Europe. The typical absence of ammonites in this stratigraphic interval potentially makes the first occurrence of Mytiloides hattini an important fossil for regional and intercontinental correlation of the Cenomanian–Turonian boundary.

@article{doi101017s002233600002045x,
    author = "Elder, William P.",
    title = "Mytiloides hattini n. sp.: a guide fossil for the base of the Turonian in the Western Interior of North America",
    year = "1991",
    journal = "Journal of Paleontology",
    abstract = "Mytiloides hattini, a new species of inoceramid bivalve from the basal Turonian (Upper Cretaceous), is described and its stratigraphic importance discussed. This inoceramid is particularly significant because its first occurrence can be used as a marker for the base of the Turonian in strata that typically contain no ammonites and few other taxa. The lowest occurrence of Mytiloides hattini is characterized by abundant specimens over wide regions of the Western Interior of North America; this species also apparently occurs in the lowest Turonian strata of western Europe. The typical absence of ammonites in this stratigraphic interval potentially makes the first occurrence of Mytiloides hattini an important fossil for regional and intercontinental correlation of the Cenomanian–Turonian boundary.",
    url = "https://doi.org/10.1017/s002233600002045x",
    doi = "10.1017/s002233600002045x",
    openalex = "W177004515",
    references = "doi103133pp1271"
}

@article{doi101127nos2419911,
    author = "Kennedy, W. J. and Cobban, W. A.",
    title = "Stratigraphy and interregional correlation of the Cenomanian-Turonian transition in the Western Interior of the United States near Pueblo, Colorado, a potential boundary stratotype for the base of the Turonian stage",
    year = "1991",
    journal = "Newsletters on Stratigraphy",
    url = "https://doi.org/10.1127/nos/24/1991/1",
    doi = "10.1127/nos/24/1991/1",
    openalex = "W2606048668"
}

The Roxton Limestone Member at the top of the Gober Chalk in northeast Texas yields a rich fauna, dominated by Baculites haresi Reeside, 1927, and Inoceramus balticus Boehm, 1909, with sparse occurrences of Pachydiscus cf. P. paulsoni (Young, 1963), Anapachydiscus sp. juv., Placenticeras placenta (DeKay, 1828), Hoplitoplacenticeras aff. H. plasticum (Paulcke, 1907), Menabites (Delawarella) delawarensis (Morton, 1830), M. (D.) danei (Young, 1963), M. (D.) aff. M. (D.) vanuxemi (Morton, 1830), Submortoniceras vandalinaense Young, 1963, Submortoniceras sp., Eubostrychoceras sp., and Scaphites hippocrepis (DeKay, 1828) III. The presence of S. hippocrepis III suggests a late early Campanian age assignment for the fauna. The assemblage includes species known from the Western Interior, Gulf Coast, Atlantic seaboard, and western Europe.

@article{doi101017s0022336000033990,
    author = "Cobban, W. A. and Kennedy, William J.",
    title = "Campanian ammonites from the Upper Cretaceous Gober Chalk of Lamar County, Texas",
    year = "1992",
    journal = "Journal of Paleontology",
    abstract = "The Roxton Limestone Member at the top of the Gober Chalk in northeast Texas yields a rich fauna, dominated by Baculites haresi Reeside, 1927, and Inoceramus balticus Boehm, 1909, with sparse occurrences of Pachydiscus cf. P. paulsoni (Young, 1963), Anapachydiscus sp. juv., Placenticeras placenta (DeKay, 1828), Hoplitoplacenticeras aff. H. plasticum (Paulcke, 1907), Menabites (Delawarella) delawarensis (Morton, 1830), M. (D.) danei (Young, 1963), M. (D.) aff. M. (D.) vanuxemi (Morton, 1830), Submortoniceras vandalinaense Young, 1963, Submortoniceras sp., Eubostrychoceras sp., and Scaphites hippocrepis (DeKay, 1828) III. The presence of S. hippocrepis III suggests a late early Campanian age assignment for the fauna. The assemblage includes species known from the Western Interior, Gulf Coast, Atlantic seaboard, and western Europe.",
    url = "https://doi.org/10.1017/s0022336000033990",
    doi = "10.1017/s0022336000033990",
    openalex = "W2269614068",
    references = "doi103133pp151, openalexw656711665"
}

The Saratoga Chalk of Arkansas yields a rich ammonite fauna of 17 species, referred to the Nostoceras (N.) hyatti zone. Recognition that the northwest European N. (N.) pozaryskii Blaszkiewicz, 1980, is a synonym of N. (N.) hyatti Stephenson, 1941, and N. (N.) helicinum (Shumard, 1861) dates the zone as latest Campanian on the basis of co-occurrence with Belemnitella langei Jeletzky, 1948, in Poland. Most previous estimates of the Campanian–Maastrichtian boundary in the Gulf Coast have been drawn at too low a level, at least in terms of ammonite faunas. Elements of the N. (N.) hyatti zone fauna occur in the United States Western Interior, and show the base of the Maastrichtian there to lie above the Baculites jenseni zone.

@article{doi101017s002233600003688x,
    author = "Kennedy, William J. and Cobban, W. A.",
    title = "Ammonites from the Saratoga Chalk (Upper Cretaceous), Arkansas",
    year = "1993",
    journal = "Journal of Paleontology",
    abstract = "The Saratoga Chalk of Arkansas yields a rich ammonite fauna of 17 species, referred to the Nostoceras (N.) hyatti zone. Recognition that the northwest European N. (N.) pozaryskii Blaszkiewicz, 1980, is a synonym of N. (N.) hyatti Stephenson, 1941, and N. (N.) helicinum (Shumard, 1861) dates the zone as latest Campanian on the basis of co-occurrence with Belemnitella langei Jeletzky, 1948, in Poland. Most previous estimates of the Campanian–Maastrichtian boundary in the Gulf Coast have been drawn at too low a level, at least in terms of ammonite faunas. Elements of the N. (N.) hyatti zone fauna occur in the United States Western Interior, and show the base of the Maastrichtian there to lie above the Baculites jenseni zone.",
    url = "https://doi.org/10.1017/s002233600003688x",
    doi = "10.1017/s002233600003688x",
    openalex = "W2297273614",
    references = "doi101130mem71p1, doi105962bhltitle19929, openalexw2335826749"
}

"Well-preserved scaphitid ammonites from the type area of the Upper Cretaceous Fox Hills Formation in north-central South Dakota are the primary focus of this study; also included are scaphites from the uppermost Pierre Shale in this area and from the Fox Hills Formation in the Lance Creek-Red Bird area of eastern Wyoming. The Fox Hills beds represent the marginal marine phase of the progradational sequence marking the final withdrawal of the Cretaceous sea from the Western Interior. Within this marine sequence, which lies above the Baculites clinolobatus Range Zone, the following three range zones based on scaphites are recognized: Jeletzkytes nebrascensis Range Zone; Hoploscaphites nicolletii Range Zone; Hoploscaphites birkelundi Range Zone. Based on recent correlation studies using macro- and microfossils, the H. nicolletii and J. nebrascensis zones equate with the lower Upper Maastrichtian of the European boreal province; the H. birkelundi Zone is either uppermost Lower Maastrichtian or possibly lowermost Upper Maastrichtan. More than 2500 adults and several hundred juveniles were examined in this study. These specimens fall into three genera: Hoploscaphites Nowak, 1911, Jeletzkytes Riccardi, 1983, and Discoscaphites Meek, 1876. Hoploscaphites includes H. nicolletii (Morton, 1842), H. comprimus (Owen, 1852), H. melloi, n. sp., and H. birkelundi, n. sp. This genus consists of compressed shells with or without ventrolateral tubercles, and less commonly, umbilical tubercles or bullae. Jeletzkytes includes J. spedeni, n. sp., J. nebrascensis (Owen, 1852), and J. dorfi, n. sp. and is characterized by medium to large shells with conspicuous ventrolateral and umbilicolateral tubercles. Discoscaphites includes D. conradi (Morton, 1834), D. gulosus (Morton, 1834), and a micromorphic species, D. rossi, n. sp. This genus consists of small to medium shells with multiple rows of tubercles. A cladistic analysis using the genus Scaphites Parkinson, 1811 as an outgroup indicates that Hoploscaphites and Jeletzkytes are more closely related to each other than either is to Discoscaphites. The excellent preservation of these scaphites permits study of their ontogeny. The embryonic shell or ammonitella is approximately 700 [micrometers] in diameter and exhibits a tuberculate micro-ornamentation. The ammonitella is spheroidal in Hoploscaphites and Jeletzkytes and ellipsoidal in Discoscaphites. The juvenile shell is closely coiled and expands gradually in whorl width and whorl height. There is a slight change at approximately 5 mm shell diameter, coincident with the first appearance of ornament in the form of ribs. Ventrolateral tubercles appear as early as 10-15 mm shell diameter followed by the development of flank tubercles in species of Discoscaphites and Jeletzkytes. Rows of flank tubercles develop in succession from the ventrolateral margin toward the umbilicus. The angular length of the juvenile body chamber averages approximately 240°. The mature shell is not as tightly coiled as that of the juvenile. The body chamber consists of an elongate shaft and recurved hook terminating in a constricted aperture. The change in the shape of the body chamber coincides with a change in the pattern of ornamentation. Large ventrolateral tubercles occur on the shaft in species of Jeletzkytes and in some species of Hoploscaphites. Muscle attachment areas on the body chamber are indicated by thin layers of myostracum preserved on steinkerns. All species are strongly dimorphic at maturity. The average size of macroconchs is significantly larger than that of microconchs, but dimorphs are primarily distinguished on the basis of shape. The body chamber of macroconchs increases abruptly in height, resulting in a nearly straight umbilical shoulder and a relatively small umbilicus whereas the body chamber of microconchs expands only gradually in size; the umbilical shoulder parallels the curve of the venter and the umbilicus is relatively broad. Macroconchs tend to be more sharply differentiated morphologically between species than are microconchs. In species of Hoploscaphites and Discoscaphites, septal approximation occurs over more chambers and is more marked in macroconchs than in microconchs. Macroconchs are more abundant than microconchs in most species. Remains of upper and lower mandibles are associated with all three scaphite genera. The lower mandible is composed of paired, externally convex plates that lie opposite one another, their ventral commissure aligned along the plane of bilateral symmetry. The plates are chitinous with an outer layer of calcite. The upper mandible, which is composed only of chitin, is a single element with two vertical, winglike, lateral parts that converge anteriorly to form a beaklike structure. Like the plates of the lower mandible, wings of the upper mandible are ornamented with concentric ribs that follow finer growth lines. Commonly occurring with mandible remains are hollow chitinous structures consisting of an inverted cup-shaped base 2-5 mm in diameter from which two hornlike projections taper upward to sharp points. Their identification is uncertain but, based on their uniform shape, they may represent hooklike structures rather than radular elements"--P. 6.

@article{openalexw1919763799,
    author = "Landman, Neil H. and Waage, Karl",
    title = "Scaphitid ammonites of the Upper Cretaceous (Maastrichtian) Fox Hills Formation in South Dakota and Wyoming. Bulletin of the AMNH; no. 215",
    year = "1993",
    journal = "Biodiversity Heritage Library (Smithsonian Institution)",
    abstract = {"Well-preserved scaphitid ammonites from the type area of the Upper Cretaceous Fox Hills Formation in north-central South Dakota are the primary focus of this study; also included are scaphites from the uppermost Pierre Shale in this area and from the Fox Hills Formation in the Lance Creek-Red Bird area of eastern Wyoming. The Fox Hills beds represent the marginal marine phase of the progradational sequence marking the final withdrawal of the Cretaceous sea from the Western Interior. Within this marine sequence, which lies above the Baculites clinolobatus Range Zone, the following three range zones based on scaphites are recognized: Jeletzkytes nebrascensis Range Zone; Hoploscaphites nicolletii Range Zone; Hoploscaphites birkelundi Range Zone. Based on recent correlation studies using macro- and microfossils, the H. nicolletii and J. nebrascensis zones equate with the lower Upper Maastrichtian of the European boreal province; the H. birkelundi Zone is either uppermost Lower Maastrichtian or possibly lowermost Upper Maastrichtan. More than 2500 adults and several hundred juveniles were examined in this study. These specimens fall into three genera: Hoploscaphites Nowak, 1911, Jeletzkytes Riccardi, 1983, and Discoscaphites Meek, 1876. Hoploscaphites includes H. nicolletii (Morton, 1842), H. comprimus (Owen, 1852), H. melloi, n. sp., and H. birkelundi, n. sp. This genus consists of compressed shells with or without ventrolateral tubercles, and less commonly, umbilical tubercles or bullae. Jeletzkytes includes J. spedeni, n. sp., J. nebrascensis (Owen, 1852), and J. dorfi, n. sp. and is characterized by medium to large shells with conspicuous ventrolateral and umbilicolateral tubercles. Discoscaphites includes D. conradi (Morton, 1834), D. gulosus (Morton, 1834), and a micromorphic species, D. rossi, n. sp. This genus consists of small to medium shells with multiple rows of tubercles. A cladistic analysis using the genus Scaphites Parkinson, 1811 as an outgroup indicates that Hoploscaphites and Jeletzkytes are more closely related to each other than either is to Discoscaphites. The excellent preservation of these scaphites permits study of their ontogeny. The embryonic shell or ammonitella is approximately 700 [micrometers] in diameter and exhibits a tuberculate micro-ornamentation. The ammonitella is spheroidal in Hoploscaphites and Jeletzkytes and ellipsoidal in Discoscaphites. The juvenile shell is closely coiled and expands gradually in whorl width and whorl height. There is a slight change at approximately 5 mm shell diameter, coincident with the first appearance of ornament in the form of ribs. Ventrolateral tubercles appear as early as 10-15 mm shell diameter followed by the development of flank tubercles in species of Discoscaphites and Jeletzkytes. Rows of flank tubercles develop in succession from the ventrolateral margin toward the umbilicus. The angular length of the juvenile body chamber averages approximately 240°. The mature shell is not as tightly coiled as that of the juvenile. The body chamber consists of an elongate shaft and recurved hook terminating in a constricted aperture. The change in the shape of the body chamber coincides with a change in the pattern of ornamentation. Large ventrolateral tubercles occur on the shaft in species of Jeletzkytes and in some species of Hoploscaphites. Muscle attachment areas on the body chamber are indicated by thin layers of myostracum preserved on steinkerns. All species are strongly dimorphic at maturity. The average size of macroconchs is significantly larger than that of microconchs, but dimorphs are primarily distinguished on the basis of shape. The body chamber of macroconchs increases abruptly in height, resulting in a nearly straight umbilical shoulder and a relatively small umbilicus whereas the body chamber of microconchs expands only gradually in size; the umbilical shoulder parallels the curve of the venter and the umbilicus is relatively broad. Macroconchs tend to be more sharply differentiated morphologically between species than are microconchs. In species of Hoploscaphites and Discoscaphites, septal approximation occurs over more chambers and is more marked in macroconchs than in microconchs. Macroconchs are more abundant than microconchs in most species. Remains of upper and lower mandibles are associated with all three scaphite genera. The lower mandible is composed of paired, externally convex plates that lie opposite one another, their ventral commissure aligned along the plane of bilateral symmetry. The plates are chitinous with an outer layer of calcite. The upper mandible, which is composed only of chitin, is a single element with two vertical, winglike, lateral parts that converge anteriorly to form a beaklike structure. Like the plates of the lower mandible, wings of the upper mandible are ornamented with concentric ribs that follow finer growth lines. Commonly occurring with mandible remains are hollow chitinous structures consisting of an inverted cup-shaped base 2-5 mm in diameter from which two hornlike projections taper upward to sharp points. Their identification is uncertain but, based on their uniform shape, they may represent hooklike structures rather than radular elements"--P. 6.},
    openalex = "W1919763799"
}

@article{openalexw2771306584,
    author = "Kauffman, Erle G. and Sageman, Bradley B. and Kirkland, James I. and Elder, William P. and Harries, Peter J. and Villamil, Tomas",
    title = "Molluscan biostratigraphy of the Cretaceous Western Interior Basin, North America",
    year = "1993",
    openalex = "W2771306584"
}

@article{doi1010160031018294900248,
    author = "McArthur, J.M. and Kennedy, William J. and Chen, Mingyang and Thirlwall, M.F. and Gale, Andrew S.",
    title = "Strontium isotope stratigraphy for Late Cretaceous time: Direct numerical calibration of the Sr isotope curve based on the US Western Interior",
    year = "1994",
    journal = "Palaeogeography Palaeoclimatology Palaeoecology",
    url = "https://doi.org/10.1016/0031-0182(94)90024-8",
    doi = "10.1016/0031-0182(94)90024-8",
    openalex = "W2059144124",
    references = "cobban1984midcretaceous, doi101016019566719190037d, doi101017s0016756800019580, doi103133b1787l, doi103133pp776, openalexw3198721165"
}

Shale of the Cretaceous lower Colorado Group extends across the subsurface of the Western Canada Sedimentary Basin (WCSB) and along the length of the Rocky Mountain Foothills. Four regionally mappable shale units are recognized by their distinctive geochemical, mineralogical, biofacies and sedimentological characteristics: the Late Albian Westgate, the Early Cenomanian Fish Scales, the Middle to Late Cenomanian Belle Fourche, and the latest Cenomanian to Middle Turonian Second White Specks Formation. These units were deposited in a foreland basin during a period of overall sea-level rise punctuated by periods of tectonically induced, relative sea-level falls. The Westgate Formation is a progradational siltstone to mudstone having a low total organic carbon (TOC) content (< 2 wt %) of dominantly Type III organic matter (OM). The Westgate was deposited above storm wave-base in the Mowry Sea. The inner to middle neritic foraminiferal assemblage (Milliammina manitobensis Zone) and oxygen isotope composition of early diagenetic carbonate concretions indicate a cool, low-salinity water mass of Boreal affinity. Compacted sedimentation rates ranged from 1 to 6 cm/10 3 yrs. The Fish Scales Formation is a transgressive mudstone to claystone with TOC contents of up to 8 wt % of mixed types II and III OM. The basal conglomeratic layer indicates a drastic environmental change at the end of the Albian. The water column was stratified with widespread anoxic bottom waters, as is indicated by well-laminated sediments and the absence of benthic foraminifera. Compacted sedimentation rates ranged from 1 to 2 cm/10 3 yrs. The contact between between the Fish Scales and the Belle Fourche formations is gradational, signifying a gradual improvement of benthic conditions. OM changes to Type III and the abundance is generally less than 2 wt%. By this time, the seaway connecting Boreal and Tethyan water masses was established but waters of Boreal affinity were dominant in the WCSB. The northwestern part of the basin was influenced by the progradation of deltaic sediments of the Dunvegan Formation. Compacted sedimentation rates ranged from 0.7 to 5.0 cm/10 3 yrs. The laminated marlstones to limestones of the Second White Specks Formation were deposited under dominantly anoxic conditions beneath an increased water column that fostered fully marine conditions. Increased water depths allowed Tethyan planktonic foraminifera and nannofossils to migrate into the WCSB. These conditions resulted in increased TOC contents of up to 12 wt% of Type II OM. Bottom currents reworked bioclastic sediments deposited below storm wave-base. Compacted sedimentation rates ranged from 1.3 to 2.5 cm/10 3 yrs. The early diagenesis of lower Colorado Group shales is dominated by sulfate reduction and methanogenesis. These microbially mediated processes resulted in the formation of pyrite, carbonate concretions and some clay mineral neoformation, primarily kaolinite. Carbonate concretions in the Westgate, Fish Scales and Belle Fourche formations are dominantly siderite, whereas those of the Second White Specks Formaton are calcite. Alteration of volcanic ash and hydrolysis of K-aluminosilicates resulted in smectite, mixed-layer illite/smectite and kaolinite authigenesis. Rock-Eval pyrolysis data indicate that, west of approximately 114° longitude, the lower Colorado Group shales are mature source rocks. The Second White Specks Formation is an effective source rock and apparently there is active localized hydrocarbon migration from the Fold and Thrust Belt. It is inferred that hydrocarbon migration and production from the Second White Specks Formation is controlled largely by fractures.

@book{doi104095211004,
    author = "Bloch, J D and Schröder-Adams, Claudia J. and Leckie, D A and Craig, Jim and McIntyre, David J.",
    title = "Sedimentology, micropaleontology, geochemistry, and hydrocarbon potential of shale from the Cretaceous lower Colorado Group in western Canada",
    year = "1999",
    abstract = "Shale of the Cretaceous lower Colorado Group extends across the subsurface of the Western Canada Sedimentary Basin (WCSB) and along the length of the Rocky Mountain Foothills. Four regionally mappable shale units are recognized by their distinctive geochemical, mineralogical, biofacies and sedimentological characteristics: the Late Albian Westgate, the Early Cenomanian Fish Scales, the Middle to Late Cenomanian Belle Fourche, and the latest Cenomanian to Middle Turonian Second White Specks Formation. These units were deposited in a foreland basin during a period of overall sea-level rise punctuated by periods of tectonically induced, relative sea-level falls. The Westgate Formation is a progradational siltstone to mudstone having a low total organic carbon (TOC) content (\< 2 wt \%) of dominantly Type III organic matter (OM). The Westgate was deposited above storm wave-base in the Mowry Sea. The inner to middle neritic foraminiferal assemblage (Milliammina manitobensis Zone) and oxygen isotope composition of early diagenetic carbonate concretions indicate a cool, low-salinity water mass of Boreal affinity. Compacted sedimentation rates ranged from 1 to 6 cm/10 3 yrs. The Fish Scales Formation is a transgressive mudstone to claystone with TOC contents of up to 8 wt \% of mixed types II and III OM. The basal conglomeratic layer indicates a drastic environmental change at the end of the Albian. The water column was stratified with widespread anoxic bottom waters, as is indicated by well-laminated sediments and the absence of benthic foraminifera. Compacted sedimentation rates ranged from 1 to 2 cm/10 3 yrs. The contact between between the Fish Scales and the Belle Fourche formations is gradational, signifying a gradual improvement of benthic conditions. OM changes to Type III and the abundance is generally less than 2 wt\%. By this time, the seaway connecting Boreal and Tethyan water masses was established but waters of Boreal affinity were dominant in the WCSB. The northwestern part of the basin was influenced by the progradation of deltaic sediments of the Dunvegan Formation. Compacted sedimentation rates ranged from 0.7 to 5.0 cm/10 3 yrs. The laminated marlstones to limestones of the Second White Specks Formation were deposited under dominantly anoxic conditions beneath an increased water column that fostered fully marine conditions. Increased water depths allowed Tethyan planktonic foraminifera and nannofossils to migrate into the WCSB. These conditions resulted in increased TOC contents of up to 12 wt\% of Type II OM. Bottom currents reworked bioclastic sediments deposited below storm wave-base. Compacted sedimentation rates ranged from 1.3 to 2.5 cm/10 3 yrs. The early diagenesis of lower Colorado Group shales is dominated by sulfate reduction and methanogenesis. These microbially mediated processes resulted in the formation of pyrite, carbonate concretions and some clay mineral neoformation, primarily kaolinite. Carbonate concretions in the Westgate, Fish Scales and Belle Fourche formations are dominantly siderite, whereas those of the Second White Specks Formaton are calcite. Alteration of volcanic ash and hydrolysis of K-aluminosilicates resulted in smectite, mixed-layer illite/smectite and kaolinite authigenesis. Rock-Eval pyrolysis data indicate that, west of approximately 114° longitude, the lower Colorado Group shales are mature source rocks. The Second White Specks Formation is an effective source rock and apparently there is active localized hydrocarbon migration from the Fold and Thrust Belt. It is inferred that hydrocarbon migration and production from the Second White Specks Formation is controlled largely by fractures.",
    url = "https://doi.org/10.4095/211004",
    doi = "10.4095/211004",
    openalex = "W2908653167"
}

New fossil collections provide additional information about the late Campanian and Maastrichtian ammonites from the Navesink Formation of New Jersey. Late Campanian ammonites include Pseudophyllites indra (Forbes, 1846), Nostoceras (N.) approximans (Conrad, 1855) (of which Nostoceras (N.) stantoni Hyatt, 1894, is a synonym), Nostoceras (N.) hyatti Stephenson, 1941, Nostoceras (N.) pauper (Whitfield, 1892), Didymoceras cf. D. draconis (Stephenson, 1941), Exiteloceras rude n. sp., Hoploscaphites pumilus (Stephenson, 1941), and Jeletzkytes cf. J. nodosus (Owen, 1852). Maastrichtian ammonites from the Navesink Formation include Pachydiscus (P.) neubergicus neubergicus (Hauer, 1858), Kitchinites sp., Nostoceras (N.) alternatum (Tuomey, 1854), Baculites sp., Eubaculites cf. E. labyrinthicus (Morton, 1834), Eubaculites sp.?, Jeletzkytes cf. J. plenus (Meek, 1876), Jeletzkytes criptonodosus Riccardi, 1983, and Discoscaphites gulosus (Morton, 1834).These faunas are correlated with those of Western Europe, the Gulf Coast, and the Western Interior of the United States. The older fauna from the basal phosphatic beds of the Navesink Formation at the classic Atlantic Highlands locality is referred to the Nostoceras (N.) hyatti zone. It is late Campanian in age and equivalent to the Nostoceras (N.) pozaryskii/Belemnella langei zone in Europe and the Baculites jenseni zone in the United States Western Interior. In addition, these beds contain ammonites that range into the early Maastrichtian, as well as Pachydiscus (P.) neubergicus, whose appearance marks the base of the Maastrichtian. Thus, these phosphatic beds represent a condensed sequence that spans the late Campanian to early Maastrichtian. Ammonites also occur at other localities in the Navesink Formation in New Jersey, and correspond to higher levels in the Maastrichtian. The youngest ammonite known from the Navesink Formation, Discoscaphites gulosus, from Sewell, New Jersey, indicates a correlation with the Hoploscaphites nicolletii or Jeletzkytes nebrascensis zone of the Western Interior.

@article{doi1012060003008220003060001attafo20co2,
    author = "Kennedy, William J. and Landman, Neil H. and Cobban, W. A. and Johnson, Ralph O.",
    title = "Additions to the Ammonite Fauna of the Upper Cretaceous Navesink Formation of New Jersey",
    year = "2000",
    journal = "American Museum Novitates",
    abstract = "New fossil collections provide additional information about the late Campanian and Maastrichtian ammonites from the Navesink Formation of New Jersey. Late Campanian ammonites include Pseudophyllites indra (Forbes, 1846), Nostoceras (N.) approximans (Conrad, 1855) (of which Nostoceras (N.) stantoni Hyatt, 1894, is a synonym), Nostoceras (N.) hyatti Stephenson, 1941, Nostoceras (N.) pauper (Whitfield, 1892), Didymoceras cf. D. draconis (Stephenson, 1941), Exiteloceras rude n. sp., Hoploscaphites pumilus (Stephenson, 1941), and Jeletzkytes cf. J. nodosus (Owen, 1852). Maastrichtian ammonites from the Navesink Formation include Pachydiscus (P.) neubergicus neubergicus (Hauer, 1858), Kitchinites sp., Nostoceras (N.) alternatum (Tuomey, 1854), Baculites sp., Eubaculites cf. E. labyrinthicus (Morton, 1834), Eubaculites sp.?, Jeletzkytes cf. J. plenus (Meek, 1876), Jeletzkytes criptonodosus Riccardi, 1983, and Discoscaphites gulosus (Morton, 1834).These faunas are correlated with those of Western Europe, the Gulf Coast, and the Western Interior of the United States. The older fauna from the basal phosphatic beds of the Navesink Formation at the classic Atlantic Highlands locality is referred to the Nostoceras (N.) hyatti zone. It is late Campanian in age and equivalent to the Nostoceras (N.) pozaryskii/Belemnella langei zone in Europe and the Baculites jenseni zone in the United States Western Interior. In addition, these beds contain ammonites that range into the early Maastrichtian, as well as Pachydiscus (P.) neubergicus, whose appearance marks the base of the Maastrichtian. Thus, these phosphatic beds represent a condensed sequence that spans the late Campanian to early Maastrichtian. Ammonites also occur at other localities in the Navesink Formation in New Jersey, and correspond to higher levels in the Maastrichtian. The youngest ammonite known from the Navesink Formation, Discoscaphites gulosus, from Sewell, New Jersey, indicates a correlation with the Hoploscaphites nicolletii or Jeletzkytes nebrascensis zone of the Western Interior.",
    url = "https://doi.org/10.1206/0003-0082(2000)306<0001:attafo>2.0.co;2",
    doi = "10.1206/0003-0082(2000)306<0001:attafo>2.0.co;2",
    openalex = "W2205447093",
    references = "doi105962bhltitle19929, openalexw2768082911"
}

@article{kennedy2000late,
    author = "KENNEDY, W. J. and LANDMAN, N. H. and COBBAN, W. A. and SCOTT, G. R.",
    title = "LATE CAMPANIAN (CRETACEOUS) HETEROMORPH AMMONITES FROM THE WESTERN INTERIOR OF THE UNITED STATES",
    year = "2000",
    journal = "Bulletin of the American Museum of Natural History",
    url = "https://doi.org/10.1206/0003-0090(2000)251<0001:lcchaf>2.0.co;2",
    doi = "10.1206/0003-0090(2000)251<0001:lcchaf>2.0.co;2",
    number = "1",
    pages = "1",
    volume = "251"
}

The Collignoniceratinae of the U.S. Western Interior first appear in the lower Turonian and range through the middle, and most of the upper, Turonian. For most of their range they are important biostratigraphic indicators. A review of their biostratigraphic distribution is provided and this is followed by a revision and/or discussion of the following taxa: Cibolaites molenaari Cobban and Hook, 1983, Collignoniceras woollgari woollgari (Mantell, 1822), C. woollgari regulare Haas, 1946, C. vermilionense (Meek and Hayden, 1860), C. jorgenseni n. sp., C. percarinatum (Hall and Meek, 1856), C. praecox (Haas, 1946), Collignonicerites collisniger n. gen., n. sp., Prionocyclus hyatti (Stanton, 1894), P. albinus (Fritsch, 1872), P. macombi Meek, 1876, P. bosquensis Kennedy, 1988, P. wyomingensis Meek, 1876, P. novimexicanus (Marcou, 1858), P. quadratus Cobban, 1953, P. germari (Reuss, 1845), P. pluricostatus n. sp., Prionocyclites mite Kennedy, 1988, and Reesidites minimus Hayasaka and Fukada, 1951. Collignoniceras woollgari, Prionocyclus hyatti, P. macombi, P. wyomingensis, P. novimexicanus, P. quadratus, and P. germari have been designated as zonal species in many publications, but aside from C. woollgari, P. hyatti, and P. wyomingensis, most of these species have not been well described in terms of their intraspecific variation. In many species, there is a gracile and a robust form, which may represent sexual dimorphs, but in most instances, the sample size of adult specimens is too small to prove this.

@article{doi1012060003009020012670001arottm20co2,
    author = "Kennedy, W. J. and Cobban, W. A. and Landman, Neil H.",
    title = "A REVISION OF THE TURONIAN MEMBERS OF THE AMMONITE SUBFAMILY COLLIGNONICERATINAE FROM THE UNITED STATES WESTERN INTERIOR AND GULF COAST",
    year = "2001",
    journal = "Bulletin of the American Museum of Natural History",
    abstract = "The Collignoniceratinae of the U.S. Western Interior first appear in the lower Turonian and range through the middle, and most of the upper, Turonian. For most of their range they are important biostratigraphic indicators. A review of their biostratigraphic distribution is provided and this is followed by a revision and/or discussion of the following taxa: Cibolaites molenaari Cobban and Hook, 1983, Collignoniceras woollgari woollgari (Mantell, 1822), C. woollgari regulare Haas, 1946, C. vermilionense (Meek and Hayden, 1860), C. jorgenseni n. sp., C. percarinatum (Hall and Meek, 1856), C. praecox (Haas, 1946), Collignonicerites collisniger n. gen., n. sp., Prionocyclus hyatti (Stanton, 1894), P. albinus (Fritsch, 1872), P. macombi Meek, 1876, P. bosquensis Kennedy, 1988, P. wyomingensis Meek, 1876, P. novimexicanus (Marcou, 1858), P. quadratus Cobban, 1953, P. germari (Reuss, 1845), P. pluricostatus n. sp., Prionocyclites mite Kennedy, 1988, and Reesidites minimus Hayasaka and Fukada, 1951. Collignoniceras woollgari, Prionocyclus hyatti, P. macombi, P. wyomingensis, P. novimexicanus, P. quadratus, and P. germari have been designated as zonal species in many publications, but aside from C. woollgari, P. hyatti, and P. wyomingensis, most of these species have not been well described in terms of their intraspecific variation. In many species, there is a gracile and a robust form, which may represent sexual dimorphs, but in most instances, the sample size of adult specimens is too small to prove this.",
    url = "https://doi.org/10.1206/0003-0090(2001)267<0001:arottm>2.0.co;2",
    doi = "10.1206/0003-0090(2001)267<0001:arottm>2.0.co;2",
    openalex = "W2180487186",
    references = "openalexw2306538690"
}

Abstract Mosasaur taxa currently known from Campanian-Maastrichtian strata in the Liège-Limburg (SE Netherlands, NE Belgium) and Mons (southern Belgium) basins are listed and briefly discussed and their stratigraphic ranges indicated. Recently published and/or ongoing work on coleoid and ammonoid cephalopods in these areas allows tie points between NW Europe and the United States (Western Interior, Gulf Coast, Atlantic Seaboard) to be established. Future studies need to refine the resultant, rather crude, scheme. The ultimate aim is a more robust picture of mosasaur taxonomy, biostratigraphy and palaeobiogeography, and a detailed evaluation of migratory patterns across the Atlantic.

@article{doi101017s0016774600021065,
    author = "Jagt, John W.M.",
    title = "Stratigraphic ranges of mosasaurs in Belgium and the Netherlands (Late Cretaceous) and cephalopod-based correlations with North America",
    year = "2005",
    journal = "Netherlands Journal of Geosciences – Geologie en Mijnbouw",
    abstract = "Abstract Mosasaur taxa currently known from Campanian-Maastrichtian strata in the Liège-Limburg (SE Netherlands, NE Belgium) and Mons (southern Belgium) basins are listed and briefly discussed and their stratigraphic ranges indicated. Recently published and/or ongoing work on coleoid and ammonoid cephalopods in these areas allows tie points between NW Europe and the United States (Western Interior, Gulf Coast, Atlantic Seaboard) to be established. Future studies need to refine the resultant, rather crude, scheme. The ultimate aim is a more robust picture of mosasaur taxonomy, biostratigraphy and palaeobiogeography, and a detailed evaluation of migratory patterns across the Atlantic.",
    url = "https://doi.org/10.1017/s0016774600021065",
    doi = "10.1017/s0016774600021065",
    openalex = "W2476739369",
    references = "doi101017s0022336000061096, doi1012060003009020002510001lcchaf20co2, kennedy2000late"
}

From the Introduction: This provisional table is based mainly on the molluscan fossil record of the central and northern parts of the Western Interior of the United States. Some of the ammonite zones are known in Europe, such as Watinoceras devonense, Collignoniceras woollgari, Prionocyclus germari, Scaphites hippocrepis, Didymoceras stevensoni, and Didymoceras cheyennense, whereas more than one-half of the inoceramid zones are known also in Europe. A few of the ammonite zones are known from only a few localities, but the diagnostic species may occur in abundance. Among these are the zones of Acanthoceras granerosense, A. bellense, Dunveganoceras problematicum, Burroceras clydense, Watinoceras devonense, Collignoniceras praecox, and Scaphites mariasensis. All fossils listed in the table are in the national collection housed in Building 810 at the Federal Center, Denver, Colorado

@article{doi103133ofr20061250,
    author = "Cobban, W. A. and Walaszczyk, Ireneusz and Obradovich, John D. and McKinney, Kevin C.",
    title = "A USGS Zonal Table for the Upper Cretaceous Middle Cenomanian--Maastrichtian of the Western Interior of the United States Based on Ammonites, Inoceramids, and Radiometric Ages",
    year = "2006",
    journal = "Antarctica A Keystone in a Changing World",
    abstract = "From the Introduction: This provisional table is based mainly on the molluscan fossil record of the central and northern parts of the Western Interior of the United States. Some of the ammonite zones are known in Europe, such as Watinoceras devonense, Collignoniceras woollgari, Prionocyclus germari, Scaphites hippocrepis, Didymoceras stevensoni, and Didymoceras cheyennense, whereas more than one-half of the inoceramid zones are known also in Europe. A few of the ammonite zones are known from only a few localities, but the diagnostic species may occur in abundance. Among these are the zones of Acanthoceras granerosense, A. bellense, Dunveganoceras problematicum, Burroceras clydense, Watinoceras devonense, Collignoniceras praecox, and Scaphites mariasensis. All fossils listed in the table are in the national collection housed in Building 810 at the Federal Center, Denver, Colorado",
    url = "https://doi.org/10.3133/ofr20061250",
    doi = "10.3133/ofr20061250",
    openalex = "W104781427",
    references = "doi101017s0016756800083710, doi10108000241160410006483, doi101127nos2419911, doi101130081372361235, doi1013063d93302016b111d78645000102c1865d, doi10130683d923ed16c711d78645000102c1865d, doi1037570bgsd19843306, doi105962bhltitle59826, openalexw1483032662, openalexw1600028952, openalexw2771306584"
}

Siliciclastic and calcareous sedimentary rocks of early Late Cretaceous age in the Western Interior of the United States have been assigned to, in ascending order, the Graneros Shale, Greenhorn Formation, Carlile Shale, Niobrara Formation, and their lateral equivalents (including members of the Frontier Formation and overlying formations). This sequence of formations was deposited intermittently within and near an epicontinental seaway during the Cenomanian, Turonian, and Coniacian stages of the Cretaceous. It encloses three conspicuous and widespread disconformities that reflect regional marine regressions and transgressions as well as moderate tectonism. The disconformities and associated lacunae occupy three large areas within Wyoming, Colorado, and adjoining states. In parts of that region, as in northwestern Wyoming, a lacuna can represent more than one period of erosion and more than a single disconformity. Evidence for these disconformities was obtained from about 175 collections of molluscan fossils and from sedimentological studies of outcrops and borehole logs, supplemented by previously published data. The oldest of the three disconformities, within the Frontier Formation and partial age-equivalents (including the Carlile Shale), separates Cenomanian or lower Turonian beds from middle Turonian beds in central and western Wyoming, northwestern Colorado, and adjoining areas of Montana and Utah. In parts of that region, the maximum duration of the associated lacuna is about 3 m.y. Erosion of the region in the late early Turonian was associated with a marine regression and transgression as well as mild local tectonism. The area where strata underlying the unconformity are oldest is partly overlain by the youngest of the succeeding transgressive beds. These youngest overlying beds presumably were deposited in an uplifted area where the eroded surface had a slightly higher elevation. A younger disconformity, within the Frontier Formation and lateral equivalents, separates upper Cenomanian or lower or middle Turonian strata from middle or upper Turonian strata in central and eastern Wyoming, southwestern South Dakota, western Nebraska, and central and eastern Colorado. Locally in that region, the duration of the lacuna is as much as 5 m.y. The oldest beds underlying this contact are of late Cenomanian age and are distributed in north-central and southeastern Wyoming and in north-central Colorado, where the erosional surface was affected probably by slight uplifts and by fluvial drainage systems. In that region, the oldest beds are partly overlain by the youngest (late Turonian) of the transgressive strata. The areal distribution of the younger overlying beds in central Wyoming could indicate a westward migration of marine prodelta environments during the late Turonian. At the youngest of the three disconformities, strata of middle or late Turonian ages in the Carlile Shale and lateral equivalents are overlain by upper Turonian or lower or middle Coniacian beds of the basal Niobrara Formation in Wyoming, Colorado, Nebraska, and parts of adjoining states. The maximum duration of the associated lacuna is more than 4 m.y. in northwesternmost Wyoming and northeasternmost Nebraska. Beds underlying this disconformity are oldest (early middle Turonian) in northwestern Wyoming, northeasternmost Nebraska, and possibly elsewhere in Nebraska, which apparently were areas of comparatively higher elevation and greater truncation. The underlying beds are youngest in a northeast-trending area that extends at least from eastern Utah to northeastern Wyoming. This area presumably was uplifted less than adjoining areas possibly in the late Turonian. Strata overlying this disconformity are oldest in northeastern New Mexico and much of Colorado and are youngest in northeastern Utah, northwestern and east-central Wyoming, north-central Kansas, and northeastern Nebraska, which indicates a marine transgression that progressed mainly northward. Most of the ages used for the following calculations are estimates; consequently the resulting quantitative interpretations are speculative. The duration of the lacuna between the uppermost Carlile and the basal Niobrara increased northwestward from about 0.8 m.y. in south-central Colorado to about 4.3 m.y. in northwesternmost Wyoming. It also increased northeastward from 0.8 m.y. in Colorado to about 5.1 m.y. in northeastern Nebraska. Ages of basal beds of the Niobrara decrease northwestward from about 89.3 Ma in southeastern Colorado and northeastern New Mexico to about 88.7 Ma in northwesternmost Wyoming. Apparently, the Niobrara sea transgressed northwestward about 500 mi (805 km) from southeastern Colorado to northwesternmost Wyoming in about 0.6 m.y. Ages of the basal Niobrara also decrease toward the northeast, from 89.3 Ma in southeastern Colorado to 87.6 Ma in northeasternmost Nebraska. The Niobrara sea in that region, where chronologic data are notably sparse, possibly transgressed more than 480 mi (772 km) in about 1.7 m.y.

@article{doi102113gsrocky42295,
    author = "Merewether, E.A. and Cobban, W. A. and Obradovich, John D.",
    title = "Regional disconformities in Turonian and Coniacian (Upper Cretaceous) strata in Colorado, Wyoming, and adjoining states biochronological evidence",
    year = "2007",
    journal = "Rocky Mountain geology",
    abstract = "Siliciclastic and calcareous sedimentary rocks of early Late Cretaceous age in the Western Interior of the United States have been assigned to, in ascending order, the Graneros Shale, Greenhorn Formation, Carlile Shale, Niobrara Formation, and their lateral equivalents (including members of the Frontier Formation and overlying formations). This sequence of formations was deposited intermittently within and near an epicontinental seaway during the Cenomanian, Turonian, and Coniacian stages of the Cretaceous. It encloses three conspicuous and widespread disconformities that reflect regional marine regressions and transgressions as well as moderate tectonism. The disconformities and associated lacunae occupy three large areas within Wyoming, Colorado, and adjoining states. In parts of that region, as in northwestern Wyoming, a lacuna can represent more than one period of erosion and more than a single disconformity. Evidence for these disconformities was obtained from about 175 collections of molluscan fossils and from sedimentological studies of outcrops and borehole logs, supplemented by previously published data. The oldest of the three disconformities, within the Frontier Formation and partial age-equivalents (including the Carlile Shale), separates Cenomanian or lower Turonian beds from middle Turonian beds in central and western Wyoming, northwestern Colorado, and adjoining areas of Montana and Utah. In parts of that region, the maximum duration of the associated lacuna is about 3 m.y. Erosion of the region in the late early Turonian was associated with a marine regression and transgression as well as mild local tectonism. The area where strata underlying the unconformity are oldest is partly overlain by the youngest of the succeeding transgressive beds. These youngest overlying beds presumably were deposited in an uplifted area where the eroded surface had a slightly higher elevation. A younger disconformity, within the Frontier Formation and lateral equivalents, separates upper Cenomanian or lower or middle Turonian strata from middle or upper Turonian strata in central and eastern Wyoming, southwestern South Dakota, western Nebraska, and central and eastern Colorado. Locally in that region, the duration of the lacuna is as much as 5 m.y. The oldest beds underlying this contact are of late Cenomanian age and are distributed in north-central and southeastern Wyoming and in north-central Colorado, where the erosional surface was affected probably by slight uplifts and by fluvial drainage systems. In that region, the oldest beds are partly overlain by the youngest (late Turonian) of the transgressive strata. The areal distribution of the younger overlying beds in central Wyoming could indicate a westward migration of marine prodelta environments during the late Turonian. At the youngest of the three disconformities, strata of middle or late Turonian ages in the Carlile Shale and lateral equivalents are overlain by upper Turonian or lower or middle Coniacian beds of the basal Niobrara Formation in Wyoming, Colorado, Nebraska, and parts of adjoining states. The maximum duration of the associated lacuna is more than 4 m.y. in northwesternmost Wyoming and northeasternmost Nebraska. Beds underlying this disconformity are oldest (early middle Turonian) in northwestern Wyoming, northeasternmost Nebraska, and possibly elsewhere in Nebraska, which apparently were areas of comparatively higher elevation and greater truncation. The underlying beds are youngest in a northeast-trending area that extends at least from eastern Utah to northeastern Wyoming. This area presumably was uplifted less than adjoining areas possibly in the late Turonian. Strata overlying this disconformity are oldest in northeastern New Mexico and much of Colorado and are youngest in northeastern Utah, northwestern and east-central Wyoming, north-central Kansas, and northeastern Nebraska, which indicates a marine transgression that progressed mainly northward. Most of the ages used for the following calculations are estimates; consequently the resulting quantitative interpretations are speculative. The duration of the lacuna between the uppermost Carlile and the basal Niobrara increased northwestward from about 0.8 m.y. in south-central Colorado to about 4.3 m.y. in northwesternmost Wyoming. It also increased northeastward from 0.8 m.y. in Colorado to about 5.1 m.y. in northeastern Nebraska. Ages of basal beds of the Niobrara decrease northwestward from about 89.3 Ma in southeastern Colorado and northeastern New Mexico to about 88.7 Ma in northwesternmost Wyoming. Apparently, the Niobrara sea transgressed northwestward about 500 mi (805 km) from southeastern Colorado to northwesternmost Wyoming in about 0.6 m.y. Ages of the basal Niobrara also decrease toward the northeast, from 89.3 Ma in southeastern Colorado to 87.6 Ma in northeasternmost Nebraska. The Niobrara sea in that region, where chronologic data are notably sparse, possibly transgressed more than 480 mi (772 km) in about 1.7 m.y.",
    url = "https://doi.org/10.2113/gsrocky.42.2.95",
    doi = "10.2113/gsrocky.42.2.95",
    openalex = "W2147576078",
    references = "doi103133pp186k"
}

@incollection{doi10100797814020905306,
    author = "Yacobucci, Margaret M.",
    title = "Controls on Shell Shape in Acanthoceratid Ammonites from the Cenomanian-Turonian Western Interior Seaway",
    year = "2008",
    booktitle = "Topics in geobiology",
    url = "https://doi.org/10.1007/978-1-4020-9053-0\_6",
    doi = "10.1007/978-1-4020-9053-0\_6",
    openalex = "W147572137",
    references = "cobban1987some"
}

@article{doi101016jpalaeo200808018,
    author = "Nielsen, Karsten Schjødt and Schröder-Adams, Claudia J. and Leckie, Dale A. and Haggart, James W. and Elberdak, Khalifa",
    title = "Turonian to Santonian paleoenvironmental changes in the Cretaceous Western Interior Sea: The Carlile and Niobrara formations in southern Alberta and southwestern Saskatchewan, Canada",
    year = "2008",
    journal = "Palaeogeography Palaeoclimatology Palaeoecology",
    url = "https://doi.org/10.1016/j.palaeo.2008.08.018",
    doi = "10.1016/j.palaeo.2008.08.018",
    openalex = "W2067727424",
    references = "doi1013063d93432e16b111d78645000102c1865d"
}

A combination of biostratigraphic markers (ammonites, inoceramid bivalves) and carbon isotope excursions is employed to establish a high-resolution correlation between the middle to late Cenomanian successions of the Western Interior Basin (USA) and the Anglo-Paris Basin (southern UK). Sequences identified from sedimentologic criteria in the Pueblo succession and elsewhere in the Western Interior Basin are shown to coincide precisely with globally recognized sea-level events and were therefore under eustatic control. This evidence refutes arguments that Cenomanian sequences in the Western Interior Basin were formed by local tectonic events. The interaction of longer-term tectonic movements and more rapid eustatic change may have simply enhanced the amount of erosion associated with sequence boundaries. A crossplot of radiometric ages derived from North American bentonites against an orbitally tuned time scale developed in the Anglo-Paris Basin provides support for the argument that the sequences were controlled by the 405-k.y.-long eccentricity cycle.

@article{doi101130g24838a1,
    author = "Gale, Andrew S. and Voigt, Silke and Sageman, Bradley B. and Kennedy, William J.",
    title = "Eustatic sea-level record for the Cenomanian (Late Cretaceous)—Extension to the Western Interior Basin, USA",
    year = "2008",
    journal = "Geology",
    abstract = "A combination of biostratigraphic markers (ammonites, inoceramid bivalves) and carbon isotope excursions is employed to establish a high-resolution correlation between the middle to late Cenomanian successions of the Western Interior Basin (USA) and the Anglo-Paris Basin (southern UK). Sequences identified from sedimentologic criteria in the Pueblo succession and elsewhere in the Western Interior Basin are shown to coincide precisely with globally recognized sea-level events and were therefore under eustatic control. This evidence refutes arguments that Cenomanian sequences in the Western Interior Basin were formed by local tectonic events. The interaction of longer-term tectonic movements and more rapid eustatic change may have simply enhanced the amount of erosion associated with sequence boundaries. A crossplot of radiometric ages derived from North American bentonites against an orbitally tuned time scale developed in the Anglo-Paris Basin provides support for the argument that the sequences were controlled by the 405-k.y.-long eccentricity cycle.",
    url = "https://doi.org/10.1130/g24838a.1",
    doi = "10.1130/g24838a.1",
    openalex = "W1999869943",
    references = "cobban1984midcretaceous"
}

Updated age assignments and new collections of molluscan fossils from lower Cenomanian through upper Campanian strata in Texas permit a much refined biostratigraphic correlation with the rocks of New Mexico and the Western Interior. Generic names of many Late Cretaceous ammonites and inoceramid bivalves from Texas are updated to permit this correlation. Strata correlated in the west-to-east transect include the lower Cenomanian Beartooth Quartzite and Sarten Sandstone of southwest New Mexico, and the Eagle Mountains Formation, Del Rio Clay, Buda Limestone, and basal beds of the Chispa Summit, Ojinaga, and Boquillas Formations of the Texas–Mexico border area. Middle Cenomanian strata are lacking in southwestern New Mexico but are present in the lower parts of the Chispa Summit and Boquillas Formations in southwest Texas. Upper Cenomanian and lower Turonian rocks are present at many localities in New Mexico and Texas in the Mancos Shale and Chispa Summit, Ojinaga, and Boquillas Formations. Middle Turonian and younger rocks seem to be entirely nonmarine in southwestern New Mexico, but they are marine in the Rio Grande area in the Chispa Summit, Ojinaga, and Boquillas Formations. The upper part of the Chispa Summit and Boquillas contain late Turonian fossils. Rocks of Coniacian and Santonian age are present high in the Chispa Summit, Ojinaga, and Boquillas Formations, and in the lower part of the Austin. The San Carlos, Aguja, Pen, and Austin Formations contain fossils of Campanian age. Fossils representing at least 38 Upper Cretaceous ammonite zones are present along the transect. Collections made in recent years in southwestern New Mexico and at Sierra de Cristo Rey just west of downtown El Paso, Texas, have been well treated and do not need revision. Taxonomic names and zonations published in the pre-1970 literature on the Rio Grande area of Texas have been updated. New fossil collections from the Big Bend National Park, Texas, allow for a much refined correlation in the central part of the transect in Texas. Middle Turonian–Campanian zonation in southwest Texas is based mainly on ammonites of the Family Collignoniceratidae, as opposed to the scaphitid and baculitid ammonites that are especially abundant farther north in the Western Interior.

@article{doi1058799nmgv30n375,
    author = "Cobban, W. A. and Hook, Stephen C. and McKinney, Kevin C.",
    title = "Upper Cretaceous molluscan record along a transect from Virden, New Mexico, to Del Rio, Texas",
    year = "2008",
    journal = "New Mexico Geology",
    abstract = "Updated age assignments and new collections of molluscan fossils from lower Cenomanian through upper Campanian strata in Texas permit a much refined biostratigraphic correlation with the rocks of New Mexico and the Western Interior. Generic names of many Late Cretaceous ammonites and inoceramid bivalves from Texas are updated to permit this correlation. Strata correlated in the west-to-east transect include the lower Cenomanian Beartooth Quartzite and Sarten Sandstone of southwest New Mexico, and the Eagle Mountains Formation, Del Rio Clay, Buda Limestone, and basal beds of the Chispa Summit, Ojinaga, and Boquillas Formations of the Texas–Mexico border area. Middle Cenomanian strata are lacking in southwestern New Mexico but are present in the lower parts of the Chispa Summit and Boquillas Formations in southwest Texas. Upper Cenomanian and lower Turonian rocks are present at many localities in New Mexico and Texas in the Mancos Shale and Chispa Summit, Ojinaga, and Boquillas Formations. Middle Turonian and younger rocks seem to be entirely nonmarine in southwestern New Mexico, but they are marine in the Rio Grande area in the Chispa Summit, Ojinaga, and Boquillas Formations. The upper part of the Chispa Summit and Boquillas contain late Turonian fossils. Rocks of Coniacian and Santonian age are present high in the Chispa Summit, Ojinaga, and Boquillas Formations, and in the lower part of the Austin. The San Carlos, Aguja, Pen, and Austin Formations contain fossils of Campanian age. Fossils representing at least 38 Upper Cretaceous ammonite zones are present along the transect. Collections made in recent years in southwestern New Mexico and at Sierra de Cristo Rey just west of downtown El Paso, Texas, have been well treated and do not need revision. Taxonomic names and zonations published in the pre-1970 literature on the Rio Grande area of Texas have been updated. New fossil collections from the Big Bend National Park, Texas, allow for a much refined correlation in the central part of the transect in Texas. Middle Turonian–Campanian zonation in southwest Texas is based mainly on ammonites of the Family Collignoniceratidae, as opposed to the scaphitid and baculitid ammonites that are especially abundant farther north in the Western Interior.",
    url = "https://doi.org/10.58799/nmg-v30n3.75",
    doi = "10.58799/nmg-v30n3.75",
    openalex = "W2169782214",
    references = "cobban1971new, doi101130mem95p1, openalexw2595223531"
}

@article{doi101016jpalaeo201003008,
    author = "Gates, Terry A. and Sampson, Scott D. and Zanno, Lindsay E. and Roberts, Eric M. and Eaton, Jeffrey G. and Nydam, Randall L. and Hutchison, J. Howard and Smith, Joshua A. and Loewen, Mark A. and Getty, Michael",
    title = "Biogeography of terrestrial and freshwater vertebrates from the late Cretaceous (Campanian) Western Interior of North America",
    year = "2010",
    journal = "Palaeogeography Palaeoclimatology Palaeoecology",
    url = "https://doi.org/10.1016/j.palaeo.2010.03.008",
    doi = "10.1016/j.palaeo.2010.03.008",
    openalex = "W2157197649",
    references = "doi101016003101829090110s, doi101016jpalaeo200505014, doi10108002724634199210011475, doi101666080251"
}

Within the Western Interior Basin of North America, hundreds of small carbonate mounds associated with Late Cretaceous hydrocarbon emissions or seeps form the most extensively distributed occurrence of fossil seep mounds that is known, the Tepee Buttes. Analysis of the stratigraphic literature for the basin reveals that Tepee Butte formation occurred intermittently over a 10‐m.yr. period within a narrowly restricted paleogeographic region. The modern geographic distribution of the Tepee Buttes is constrained roughly to between 101°30′ and 105°30′W longitude and ranges from the northern Black Hills southward into southern Colorado. Four discernible intervals of seep activity are identified over a time span of 10 m.yr., from late Middle Campanian (78.7 Ma) through the Early Maastrichtian (69.1 Ma). Comparisons of the paleobiogeography of the Tepee Buttes to subsurface structures, basinal subsidence patterns, and shoreline position indicate an association between mound formation, western shoreline migration, and changes in basin tectonics. Initiation of the Tepee Butte formation is concurrent with changes in the basin tectonics and the subsequent eastward shift of maximum subsidence and sediment deposition within the basin. Mound distribution is basinward of the loci of maximum subsidence and is inferred to delineate the forebulge region of the basin during the period of Tepee Butte formation. Each determined interval of mound formation can be tied to migration of the basin’s western shoreline, with mound formation starting at maximum transgressive phases and ending at maximum regressive phases. It is postulated that shoreline migration altered sediment loading across the basin, affecting the degree of flexure of the forebulge region and thus affecting hydrocarbons emissions and mound formation.

@article{doi101086650181,
    author = "Metz, Cheryl L.",
    title = "Tectonic Controls on the Genesis and Distribution of Late Cretaceous, Western Interior Basin Hydrocarbon‐Seep Mounds (Tepee Buttes) of North America",
    year = "2010",
    journal = "The Journal of Geology",
    abstract = "Within the Western Interior Basin of North America, hundreds of small carbonate mounds associated with Late Cretaceous hydrocarbon emissions or seeps form the most extensively distributed occurrence of fossil seep mounds that is known, the Tepee Buttes. Analysis of the stratigraphic literature for the basin reveals that Tepee Butte formation occurred intermittently over a 10‐m.yr. period within a narrowly restricted paleogeographic region. The modern geographic distribution of the Tepee Buttes is constrained roughly to between 101°30′ and 105°30′W longitude and ranges from the northern Black Hills southward into southern Colorado. Four discernible intervals of seep activity are identified over a time span of 10 m.yr., from late Middle Campanian (78.7 Ma) through the Early Maastrichtian (69.1 Ma). Comparisons of the paleobiogeography of the Tepee Buttes to subsurface structures, basinal subsidence patterns, and shoreline position indicate an association between mound formation, western shoreline migration, and changes in basin tectonics. Initiation of the Tepee Butte formation is concurrent with changes in the basin tectonics and the subsequent eastward shift of maximum subsidence and sediment deposition within the basin. Mound distribution is basinward of the loci of maximum subsidence and is inferred to delineate the forebulge region of the basin during the period of Tepee Butte formation. Each determined interval of mound formation can be tied to migration of the basin’s western shoreline, with mound formation starting at maximum transgressive phases and ending at maximum regressive phases. It is postulated that shoreline migration altered sediment loading across the basin, affecting the degree of flexure of the forebulge region and thus affecting hydrocarbons emissions and mound formation.",
    url = "https://doi.org/10.1086/650181",
    doi = "10.1086/650181",
    openalex = "W2076384625",
    references = "doi1012060003009020002510001lcchaf20co2, doi1013060bda5c3f16bd11d78645000102c1865d, doi103133pp186k, kennedy2000late"
}

Scaphitid ammonites (scaphites) are common in the Upper Cretaceous Pierre Shale and Bearpaw Shale of the Western Interior of North America. We redescribe Hoploscaphites nodosus (Owen, 1852) and H. brevis (Meek, 1876) from the Baculites compressus–B. cuneatus zones of the upper Campanian. The types of both of these species were collected in the mid-19th century in what was then called Nebraska Territory, and included parts of present-day South Dakota, North Dakota, and Montana. Based on our present knowledge of the distribution of these species, the type material was probably collected from the B. compressus–B. cuneatus zones in the Pierre Shale at Sage Creek, a tributary of the Cheyenne River, Pennington County, South Dakota.Traditionally, the more robust, more coarsely ornamented scaphites (comprising the “nodosus group”) from the Pierre Shale and Bearpaw Shale were assigned to Jeletzkytes Riccardi, 1983, and the more slender, more finely ornamented scaphites were assigned to Hoploscaphites Nowak, 1911. However, our large collections of these scaphites from the Baculites compressus–B. cuneatus zones reveal a complete intergradation between the two morphological extremes, and for many specimens, the choice of genus is arbitrary. In addition, our studies of other biostratigraphic zones in the Pierre Shale and Bearpaw Shale reveal that cooccurring species of these two “genera” share more in common with each other than they do with congeneric species from other horizons. Furthermore, contrary to earlier assumptions, Jeletkytes is not endemic to the Western Interior Basin of North America and occurs, for example, in the U.S. Atlantic Coastal Plain and Europe. We thus provisionally treat Jeletzkytes as a junior subjective synonym of Hoploscaphites. This expanded definition of Hoploscaphites is consistent with present-day concepts of other scaphitid genera such as Discoscaphites Meek, 1876, and Trachyscaphites Cobban and Scott, 1964.In Hoploscaphites nodosus and H. brevis, the juvenile shell is planispirally coiled with a small umbilicus. The whorl section is initially depressed and becomes more compressed through ontogeny. The angle of the body chamber in juveniles is approximately two-thirds of a whorl. At the approach of maturity, the shell uncoils, forming a relatively long shaft and recurved hook. The ratio of whorl width to whorl height reaches a minimum value at midshaft. The apertural margin at maturity is constricted and terminates in a flared lip. Commonly, the last two or three septa, corresponding to the formation of the hook, are more closely spaced (approximated). These features indicate that the rate of growth decreased and eventually stopped at maturity (“morphogenetic countdown” associated with determinate growth). Both species of scaphites occur as dimorphs, which are referred to as macroconchs (presumably females) and microconchs (presumably males). In samples of specimens of the same species within a single concretion, macroconchs are approximately 20% larger than microconchs. In addition to size, dimorphs are distinguished by differences in shape, including the presence or absence of an umbilical bulge, the size of the umbilical diameter, the outline of the umbilical shoulder relative to that of the venter in side view, and the relative change in whorl height in passing from the mature phragmocone to the shaft of the body chamber.The holotype of Hoploscaphites nodosus, by monotypy, is UC 6381, the original of Scaphites nodosus Owen (1852: 581, pl. 8, fig. 4). Adults exhibit a range of variation in size, degree of compression, and coarseness of ornament. The exposed phragmocone occupies most of the coiled portion of the shell, and is approximately two-thirds of a whorl in angular length. Adults are large (LMAX averages 91.8 mm in macroconchs and 78.0 mm in microconchs) and ellipsoidal in side view, with a strongly recurved hook (apertural angle averages 73° in macroconchs). The ratio of whorl width to whorl heigh

@article{doi1012066591,
    author = "Landman, Neil H. and Kennedy, W. J. and Cobban, W. A. and Larson, Neal L.",
    title = "Scaphites of the “Nodosus Group” from the Upper Cretaceous (Campanian) of the Western Interior of North America",
    year = "2010",
    journal = "Bulletin of the American Museum of Natural History",
    abstract = "Scaphitid ammonites (scaphites) are common in the Upper Cretaceous Pierre Shale and Bearpaw Shale of the Western Interior of North America. We redescribe Hoploscaphites nodosus (Owen, 1852) and H. brevis (Meek, 1876) from the Baculites compressus–B. cuneatus zones of the upper Campanian. The types of both of these species were collected in the mid-19th century in what was then called Nebraska Territory, and included parts of present-day South Dakota, North Dakota, and Montana. Based on our present knowledge of the distribution of these species, the type material was probably collected from the B. compressus–B. cuneatus zones in the Pierre Shale at Sage Creek, a tributary of the Cheyenne River, Pennington County, South Dakota.Traditionally, the more robust, more coarsely ornamented scaphites (comprising the “nodosus group”) from the Pierre Shale and Bearpaw Shale were assigned to Jeletzkytes Riccardi, 1983, and the more slender, more finely ornamented scaphites were assigned to Hoploscaphites Nowak, 1911. However, our large collections of these scaphites from the Baculites compressus–B. cuneatus zones reveal a complete intergradation between the two morphological extremes, and for many specimens, the choice of genus is arbitrary. In addition, our studies of other biostratigraphic zones in the Pierre Shale and Bearpaw Shale reveal that cooccurring species of these two “genera” share more in common with each other than they do with congeneric species from other horizons. Furthermore, contrary to earlier assumptions, Jeletkytes is not endemic to the Western Interior Basin of North America and occurs, for example, in the U.S. Atlantic Coastal Plain and Europe. We thus provisionally treat Jeletzkytes as a junior subjective synonym of Hoploscaphites. This expanded definition of Hoploscaphites is consistent with present-day concepts of other scaphitid genera such as Discoscaphites Meek, 1876, and Trachyscaphites Cobban and Scott, 1964.In Hoploscaphites nodosus and H. brevis, the juvenile shell is planispirally coiled with a small umbilicus. The whorl section is initially depressed and becomes more compressed through ontogeny. The angle of the body chamber in juveniles is approximately two-thirds of a whorl. At the approach of maturity, the shell uncoils, forming a relatively long shaft and recurved hook. The ratio of whorl width to whorl height reaches a minimum value at midshaft. The apertural margin at maturity is constricted and terminates in a flared lip. Commonly, the last two or three septa, corresponding to the formation of the hook, are more closely spaced (approximated). These features indicate that the rate of growth decreased and eventually stopped at maturity (“morphogenetic countdown” associated with determinate growth). Both species of scaphites occur as dimorphs, which are referred to as macroconchs (presumably females) and microconchs (presumably males). In samples of specimens of the same species within a single concretion, macroconchs are approximately 20\% larger than microconchs. In addition to size, dimorphs are distinguished by differences in shape, including the presence or absence of an umbilical bulge, the size of the umbilical diameter, the outline of the umbilical shoulder relative to that of the venter in side view, and the relative change in whorl height in passing from the mature phragmocone to the shaft of the body chamber.The holotype of Hoploscaphites nodosus, by monotypy, is UC 6381, the original of Scaphites nodosus Owen (1852: 581, pl. 8, fig. 4). Adults exhibit a range of variation in size, degree of compression, and coarseness of ornament. The exposed phragmocone occupies most of the coiled portion of the shell, and is approximately two-thirds of a whorl in angular length. Adults are large (LMAX averages 91.8 mm in macroconchs and 78.0 mm in microconchs) and ellipsoidal in side view, with a strongly recurved hook (apertural angle averages 73° in macroconchs). The ratio of whorl width to whorl heigh",
    url = "https://doi.org/10.1206/659.1",
    doi = "10.1206/659.1",
    openalex = "W2157595576",
    references = "doi101007978140206806513, doi10100797894017963095, doi101016s001600323892229x, doi101038114085a0, doi101093nqs5vi146318i, doi101126science11282807, doi1012060003009020073031cfttbi20co2, doi1034194bullgguv566590, doi105281zenodo16219869, openalexw1561111624, openalexw2343813256, openalexw2510542759, openalexw2592545764, openalexw2751580477, openalexw2912219260, openalexw2937684811, openalexw657396478, openalexw821285779"
}

Ammonites are prominent in macroevolutionary studies because of their abundance and diversity in the fossil record, but their paleobiology and position in the marine food web are not well understood due to the lack of preserved soft tissue. We present three-dimensional reconstructions of the buccal apparatus in the Mesozoic ammonite Baculites with the use of synchrotron x-ray microtomography. Buccal mass morphology, combined with the coexistence of food remains found in the buccal mass, suggests that these ammonites fed on plankton. This diet may have extended to all aptychophoran ammonites, which share the same buccal mass morphology. Understanding the role of these ammonites in the Mesozoic food web provides insights into their radiation in the Early Jurassic, as well as their extinction at the end of the Cretaceous/early Paleogene.

@article{doi101126science1198793,
    author = "Kruta, Isabelle and Landman, Neil H. and Rouget, Isabelle and Cecca, Fabrizio and Tafforeau, Paul",
    title = "The Role of Ammonites in the Mesozoic Marine Food Web Revealed by Jaw Preservation",
    year = "2011",
    journal = "Science",
    abstract = "Ammonites are prominent in macroevolutionary studies because of their abundance and diversity in the fossil record, but their paleobiology and position in the marine food web are not well understood due to the lack of preserved soft tissue. We present three-dimensional reconstructions of the buccal apparatus in the Mesozoic ammonite Baculites with the use of synchrotron x-ray microtomography. Buccal mass morphology, combined with the coexistence of food remains found in the buccal mass, suggests that these ammonites fed on plankton. This diet may have extended to all aptychophoran ammonites, which share the same buccal mass morphology. Understanding the role of these ammonites in the Mesozoic food web provides insights into their radiation in the Early Jurassic, as well as their extinction at the end of the Cretaceous/early Paleogene.",
    url = "https://doi.org/10.1126/science.1198793",
    doi = "10.1126/science.1198793",
    openalex = "W2089809721",
    references = "doi1010079781402068065, doi101007978140206806513, doi101007978147579153216, doi101111j146979981995tb01785x, doi101111j150239311993tb01799x, doi101146annurevecolsys311293, doi1015159781503623088, doi1023071483846, doi105860choice270306, openalexw237938318, openalexw633062100"
}

We developed an intercalibrated astrochronologic and radioisotopic time scale for the Cenomanian-Turonian boundary (CTB) interval near the Global Stratotype Section and Point in Colorado, USA, where orbitally influenced rhythmic strata host bentonites that contain sanidine and zircon suitable for 40Ar/39Ar and U-Pb dating. Paired 40Ar/39Ar and U-Pb ages were determined from four \nbentonites that span the Vascoceras diartianum to Pseudaspidoceras fl exuosum ammonite biozones, utilizing both newly collected material and legacy sanidine samples of J. Obradovich. Comparison of the 40Ar/39Ar and U-Pb results underscores the strengths and limitations \nof each system, and supports an astronomically calibrated Fish Canyon sanidine standard age of 28.201 Ma. The radioisotopic data and published astrochronology are employed to develop a new CTB time scale, using two statistical approaches: (1) a simple integration \nthat yields a CTB age of 93.89 ± 0.14 Ma (2; total radioisotopic uncertainty), and (2) a Bayesian intercalibration that explicitly accounts for orbital time scale uncertainty, and yields a CTB age \nof 93.90 ± 0.15 Ma (95% credible interval; total radioisotopic and orbital time scale uncertainty). Both approaches fi rmly anchor the floating orbital time scale, and the Bayesian technique yields astronomically \nrecalibrated radioisotopic ages for individual bentonites, \nwith analytical uncertainties at the permil level of resolution, and total uncertainties below 2‰. Using our new results, the duration between the Cenomanian-Turonian and the Cretaceous-Paleogene boundaries is 27.94 ± 0.16 Ma, with an uncertainty of less than one half of a long eccentricity cycle.

@article{doi101130g322611,
    author = "Meyers, Stephen R. and Siewert, S. E. and Singer, Brad S. and Sageman, Bradley B. and Condon, Daniel J. and Obradovich, John D. and Jicha, Brian R. and Sawyer, David A.",
    title = "Intercalibration of radioisotopic and astrochronologic time scales for the Cenomanian-Turonian boundary interval, Western Interior Basin, USA",
    year = "2011",
    journal = "Geology",
    abstract = "We developed an intercalibrated astrochronologic and radioisotopic time scale for the Cenomanian-Turonian boundary (CTB) interval near the Global Stratotype Section and Point in Colorado, USA, where orbitally influenced rhythmic strata host bentonites that contain sanidine and zircon suitable for 40Ar/39Ar and U-Pb dating. Paired 40Ar/39Ar and U-Pb ages were determined from four \nbentonites that span the Vascoceras diartianum to Pseudaspidoceras fl exuosum ammonite biozones, utilizing both newly collected material and legacy sanidine samples of J. Obradovich. Comparison of the 40Ar/39Ar and U-Pb results underscores the strengths and limitations \nof each system, and supports an astronomically calibrated Fish Canyon sanidine standard age of 28.201 Ma. The radioisotopic data and published astrochronology are employed to develop a new CTB time scale, using two statistical approaches: (1) a simple integration \nthat yields a CTB age of 93.89 ± 0.14 Ma (2; total radioisotopic uncertainty), and (2) a Bayesian intercalibration that explicitly accounts for orbital time scale uncertainty, and yields a CTB age \nof 93.90 ± 0.15 Ma (95\% credible interval; total radioisotopic and orbital time scale uncertainty). Both approaches fi rmly anchor the floating orbital time scale, and the Bayesian technique yields astronomically \nrecalibrated radioisotopic ages for individual bentonites, \nwith analytical uncertainties at the permil level of resolution, and total uncertainties below 2‰. Using our new results, the duration between the Cenomanian-Turonian and the Cretaceous-Paleogene boundaries is 27.94 ± 0.16 Ma, with an uncertainty of less than one half of a long eccentricity cycle.",
    url = "https://doi.org/10.1130/g32261.1",
    doi = "10.1130/g32261.1",
    openalex = "W2001628935",
    references = "doi103133ofr20061250"
}

Both faunal endemicity and provincialism in the mid- and Late Cretaceous of the Pacific realm complicate the recognition of stage boundaries in that area. Correlations with other areas (e.g., Europe, United States Western Interior, Pacific coast of North and South America) therefore have to rely solely on event stratigraphy; not only extinctions, but all biotic events must be considered. During the Cretaceous, Pacific faunas were characterised not so much by the presence of typical ‘Boreal’ assemblages, but rather by the absence or extreme paucity of other widely distributed biota. Clearly, faunal similarities depended more on regional facies development than on their spatial distribution. The regional diversity curve reflects all global mass extinctions, faunal turnovers and radiations. A detailed analysis of ammonite evolution, based on mid- and Late Cretaceous sections from the Russian Pacific coast, plus a comparison with other provinces across the globe, fails to support a trend in decreasing ammonite diversity since the late Albian. On the contrary, ammonites demonstrated a high adaptive ability after each extinction event and recovered from each with new radiations.

@article{openalexw1504813726,
    author = "Jagt‐Yazykova, Elena A.",
    title = "Palaeobiogeographical and palaeobiological aspects of mid- and Late Cretaceous ammonite evolution and bio-events in the Russian Pacific",
    year = "2011",
    journal = "The Digital Academic Repository of Naturalis Biodiversity Center (Naturalis Biodiversity Center)",
    abstract = "Both faunal endemicity and provincialism in the mid- and Late Cretaceous of the Pacific realm complicate the recognition of stage boundaries in that area. Correlations with other areas (e.g., Europe, United States Western Interior, Pacific coast of North and South America) therefore have to rely solely on event stratigraphy; not only extinctions, but all biotic events must be considered. During the Cretaceous, Pacific faunas were characterised not so much by the presence of typical ‘Boreal’ assemblages, but rather by the absence or extreme paucity of other widely distributed biota. Clearly, faunal similarities depended more on regional facies development than on their spatial distribution. The regional diversity curve reflects all global mass extinctions, faunal turnovers and radiations. A detailed analysis of ammonite evolution, based on mid- and Late Cretaceous sections from the Russian Pacific coast, plus a comparison with other provinces across the globe, fails to support a trend in decreasing ammonite diversity since the late Albian. On the contrary, ammonites demonstrated a high adaptive ability after each extinction event and recovered from each with new radiations.",
    openalex = "W1504813726",
    references = "openalexw656711665"
}

@article{doi101016jepsl201211036,
    author = "Dennis, Kate J. and Cochran, J. Kirk and Landman, Neil H. and Schrag, Daniel P.",
    title = "The climate of the Late Cretaceous: New insights from the application of the carbonate clumped isotope thermometer to Western Interior Seaway macrofossil",
    year = "2012",
    journal = "Earth and Planetary Science Letters",
    url = "https://doi.org/10.1016/j.epsl.2012.11.036",
    doi = "10.1016/j.epsl.2012.11.036",
    openalex = "W2016553479",
    references = "doi101306ad46250b16f711d78645000102c1865d, doi103133ofr20061250"
}

The northern part of the North American Western Interior Sedimentary Basin has yielded well-preserved terrestrial palynomorphs whose occurrences allow the biostratigraphic characterization of the basin. Data have been compiled from sections that in composite span the latest Turonian to Paleocene. These data allow for the identification of species that are biostratigraphically useful within Alberta and adjacent portions of the basin. Progress has been made in establishing a stable biostratigraphic context for the basin using the first and last occurrences of 103 taxa. These palynomorphs provide a refined chronostratigraphic framework when combined with radiometric ages, polarity chronologies and ammonite biozonations. This framework has allowed the intrabasinal correlation of widely distributed sections in the Alberta and Montana portion of the basin and can be applied to stratigraphic problems in the more northern portion of the Western Interior Basin.

@article{doi101080019161222011642127,
    author = "Braman, Dennis R. and Sweet, A R",
    title = "Biostratigraphically useful Late Cretaceous–Paleocene Terrestrial palynomorphs from the Canadian Western Interior Sedimentary Basin",
    year = "2012",
    journal = "Palynology",
    abstract = "The northern part of the North American Western Interior Sedimentary Basin has yielded well-preserved terrestrial palynomorphs whose occurrences allow the biostratigraphic characterization of the basin. Data have been compiled from sections that in composite span the latest Turonian to Paleocene. These data allow for the identification of species that are biostratigraphically useful within Alberta and adjacent portions of the basin. Progress has been made in establishing a stable biostratigraphic context for the basin using the first and last occurrences of 103 taxa. These palynomorphs provide a refined chronostratigraphic framework when combined with radiometric ages, polarity chronologies and ammonite biozonations. This framework has allowed the intrabasinal correlation of widely distributed sections in the Alberta and Montana portion of the basin and can be applied to stratigraphic problems in the more northern portion of the Western Interior Basin.",
    url = "https://doi.org/10.1080/01916122.2011.642127",
    doi = "10.1080/01916122.2011.642127",
    openalex = "W2014918293",
    references = "doi101006cres19941022, doi101139e72101, doi1013063d93302016b111d78645000102c1865d, doi1013063d93432e16b111d78645000102c1865d, doi103133pp392a"
}

Sedimentary and paleontological samples from steep, deep-water escarpments of the Wallaby Plateau, 400 km west of Carnarvon, Western Australia, represent the first collected soft-rock geological data from this immense bathymetric high. The study of this vast marginal plateau of 100 000 km2 has been hampered by a paucity of rock data arising from difficulties in sampling in water depths of 2200–5700 m. Only modern carbonate, altered tholeiitic basalts and volcaniclastic rocks have been recorded previously. Variably fossiliferous to unfossiliferous claystone, siltstone and sandstone samples from 12 southern Wallaby Plateau stations (3015–5159 m water depths) range from interpreted paralic to shallow-water marine settings, and contain low to moderately diverse assemblages of Bivalvia, Gastropoda, Ostracoda, Foraminifera, palynomorphs, very rare nannofossils, and teleost fish fragments, which collectively point to an age range of latest Berriasian to Barremian–Aptian in the Early Cretaceous. This age range pre-dates, straddles and post-dates the breakup and opening of the Cuvier Abyssal Plain. Seismic imaging of the Wallaby Plateau exhibits a substantial thickness of both dipping and flat-lying, sub-parallel reflectors beneath parts of the Lower Cretaceous Gondwanan breakup unconformity. This information, taken together with the recent identification of Oxfordian–Kimmeridgian Foraminifera from the same location, indicates the presence of a pre-breakup sedimentary section beneath parts of the Wallaby Plateau.

@article{doi101080081200992011615864,
    author = "Stilwell, Jeffrey D. and Quilty, Patrick G. and Mantle, Daniel",
    title = "Paleontology of Early Cretaceous deep-water samples dredged from the Wallaby Plateau: new perspectives of Gondwana break-up along the Western Australian margin",
    year = "2012",
    journal = "Australian Journal of Earth Sciences",
    abstract = "Sedimentary and paleontological samples from steep, deep-water escarpments of the Wallaby Plateau, 400 km west of Carnarvon, Western Australia, represent the first collected soft-rock geological data from this immense bathymetric high. The study of this vast marginal plateau of 100 000 km2 has been hampered by a paucity of rock data arising from difficulties in sampling in water depths of 2200–5700 m. Only modern carbonate, altered tholeiitic basalts and volcaniclastic rocks have been recorded previously. Variably fossiliferous to unfossiliferous claystone, siltstone and sandstone samples from 12 southern Wallaby Plateau stations (3015–5159 m water depths) range from interpreted paralic to shallow-water marine settings, and contain low to moderately diverse assemblages of Bivalvia, Gastropoda, Ostracoda, Foraminifera, palynomorphs, very rare nannofossils, and teleost fish fragments, which collectively point to an age range of latest Berriasian to Barremian–Aptian in the Early Cretaceous. This age range pre-dates, straddles and post-dates the breakup and opening of the Cuvier Abyssal Plain. Seismic imaging of the Wallaby Plateau exhibits a substantial thickness of both dipping and flat-lying, sub-parallel reflectors beneath parts of the Lower Cretaceous Gondwanan breakup unconformity. This information, taken together with the recent identification of Oxfordian–Kimmeridgian Foraminifera from the same location, indicates the presence of a pre-breakup sedimentary section beneath parts of the Wallaby Plateau.",
    url = "https://doi.org/10.1080/08120099.2011.615864",
    doi = "10.1080/08120099.2011.615864",
    openalex = "W2053673931",
    references = "openalexw1836508436"
}

Concretions are the most characteristic mode of fossil occurrence in the Upper Cretaceous Western Interior of the United States. An in-depth analysis of a single concretion from the upper Campanian Pierre Shale, South Dakota, drawing upon sedimentology, paleontology, shell preservation, degree of encrustation, and geochemistry allows us to determine a time frame for the accumulation and burial of the organisms and the process of cementation and diagenesis of the concretion. The concretion is very fossiliferous and dominated by mollusks. Large ammonites are commonly broken up with pieces missing from the adapical end of the body chamber. This breakage pattern is widely interpreted as evidence of lethal damage, implying introduction into the burial site via predation. In contrast, smaller ammonites are nearly complete and may have died due to smothering in resuspended sediment produced by bottom currents. The concretion is rich in cephalopod jaws, which mostly appear as isolated occurrences, usually deformed, with the calcite covering (aptychus) missing. The preservation of jaws suggests that the organic debris did not remain in the taphonomically active zone for more than a few years. The concretion, thus, represents a time-averaged deposit of organisms derived from the local community. In contrast, host sediments contain fewer fossils, most of which are crushed. Oxygen and carbon isotopic composition of samples in the concretion and the host sediments reveals a two-stage diagenetic history of the concretion. First, cementation probably occurred at shallow burial depths in early diagenesis in association with the decomposition of organic matter and the oxidation of methane. Second, alteration of the shelly material and the formation of calcite crystals filling the empty chambers of ammonites probably occurred during later diagenesis in contact with meteoric water.

@article{doi102110palo2011p11105r,
    author = "Landman, Neil H. and Klofak, Susan M.",
    title = "ANATOMY OF A CONCRETION: LIFE, DEATH, AND BURIAL IN THE WESTERN INTERIOR SEAWAY",
    year = "2012",
    journal = "Palaios",
    abstract = "Concretions are the most characteristic mode of fossil occurrence in the Upper Cretaceous Western Interior of the United States. An in-depth analysis of a single concretion from the upper Campanian Pierre Shale, South Dakota, drawing upon sedimentology, paleontology, shell preservation, degree of encrustation, and geochemistry allows us to determine a time frame for the accumulation and burial of the organisms and the process of cementation and diagenesis of the concretion. The concretion is very fossiliferous and dominated by mollusks. Large ammonites are commonly broken up with pieces missing from the adapical end of the body chamber. This breakage pattern is widely interpreted as evidence of lethal damage, implying introduction into the burial site via predation. In contrast, smaller ammonites are nearly complete and may have died due to smothering in resuspended sediment produced by bottom currents. The concretion is rich in cephalopod jaws, which mostly appear as isolated occurrences, usually deformed, with the calcite covering (aptychus) missing. The preservation of jaws suggests that the organic debris did not remain in the taphonomically active zone for more than a few years. The concretion, thus, represents a time-averaged deposit of organisms derived from the local community. In contrast, host sediments contain fewer fossils, most of which are crushed. Oxygen and carbon isotopic composition of samples in the concretion and the host sediments reveals a two-stage diagenetic history of the concretion. First, cementation probably occurred at shallow burial depths in early diagenesis in association with the decomposition of organic matter and the oxidation of methane. Second, alteration of the shelly material and the formation of calcite crystals filling the empty chambers of ammonites probably occurred during later diagenesis in contact with meteoric water.",
    url = "https://doi.org/10.2110/palo.2011.p11-105r",
    doi = "10.2110/palo.2011.p11-105r",
    openalex = "W2091098601",
    references = "doi101007978140206806513, doi1012066591, openalexw2768082911, palamarczuk2011dinoflagellate"
}

Sections yielding late Maastrichtian ammonite assemblages are rare in Latin America and precise biostratigraphic correlation with European type sections remains difficult. In all, the extinction pattern of ammonites appears to differ between sites in southern high latitudes and those in the tropics to subtropics. In austral sections of Chile, and possibly also in southern Argentina, diverse assemblages range throughout most of the substage and then show a gradual decline prior to the Cretaceous-Paleogene (K-Pg) boundary. Further north, in northeast Brazil, only two genera (Diplomoceras, Pachydiscus) range into the uppermost Maastrichtian, but disappear within the last 0.3 Ma of the Cretaceous. In tropical sections of Columbia and Mexico, the decline of ammonites started earlier and Sphenodiscus is the last ammonite known to occur in the late Maastrichtian. In all sections revised here the disappearance of ammonites was completed prior to the end of the Maastrichtian and was thus independent of the asteroid impact at, or near, the end of the Cretaceous.

@article{doi104202app20110042,
    author = "Stinnesbeck, Wolfgang and Ifrlm, Christina and Salazar, Christian",
    title = "The Last Cretaceous Ammonites in Latin America",
    year = "2012",
    journal = "Acta Palaeontologica Polonica",
    abstract = "Sections yielding late Maastrichtian ammonite assemblages are rare in Latin America and precise biostratigraphic correlation with European type sections remains difficult. In all, the extinction pattern of ammonites appears to differ between sites in southern high latitudes and those in the tropics to subtropics. In austral sections of Chile, and possibly also in southern Argentina, diverse assemblages range throughout most of the substage and then show a gradual decline prior to the Cretaceous-Paleogene (K-Pg) boundary. Further north, in northeast Brazil, only two genera (Diplomoceras, Pachydiscus) range into the uppermost Maastrichtian, but disappear within the last 0.3 Ma of the Cretaceous. In tropical sections of Columbia and Mexico, the decline of ammonites started earlier and Sphenodiscus is the last ammonite known to occur in the late Maastrichtian. In all sections revised here the disappearance of ammonites was completed prior to the end of the Maastrichtian and was thus independent of the asteroid impact at, or near, the end of the Cretaceous.",
    url = "https://doi.org/10.4202/app.2011.0042",
    doi = "10.4202/app.2011.0042",
    openalex = "W2139292871",
    references = "doi101017s0022336000061096"
}

There is an unusually rich, Late Campanian (Upper Cretaceous), molluscan fauna from the Coon Creek Formation at its type locality, 7 1/2 miles north of Adamsville, McNairy County, Tennessee. The ammonite fauna is a typical, late Campanian, Gulf Coast fauna consisting almost entirely of aberrant ammonites and only one tightly coiled, planispiral form. A few authors have published on the fauna from this locality, most notably Bruce Wade, who published on the entire known fauna; Norman Sohl, who published on the gastropods; Cobban and Kennedy who published on the ammonites; and Brister and Young, who published an overview on the fauna and history of Coon Creek at the type locality from the extensive collections made by the Pink Palace Museum. Except for Discoscaphites the ammonite fauna from this locality compares both at a species level and stratigraphically with the fauna from the Nacatoch Sand in Kaufman and Navarro Counties of Texas (Stephenson, 1941). Except for Discoscaphites nearly all of the ammonite fauna also correlates to the Baculites cuneatus through Baculites jenseni Zones of the Pierre and Bearpaw Shales in the Western Interior, most notably to that from the Middle Park and Fort Collins area of Colorado as reported by Kennedy et al. (2000). Because the aragonitic shell of this cephalopod fauna is so well preserved at this locality it makes it possible to give a more complete description of some of the heteromorph ammonite species than had been previously done, most importantly the rib indexes. Both invertebrate and vertebrate researchers have published that the fauna from the type locality of the Coon Creek Formation constitutes a lower Maastrichtian fauna. The presence of Cirroceras conradi, Hoploscaphites reesidei, Solenoceras reesidei, S. texanum, and Nostoceras (Nostoceras) hyatti places the age of the Coon Creek Tongue at the type locality at upper Late Campanian (72-71.5 MYA), the equivalent age of the Baculites reesidei through B. jenseni Zones of the Western Interior. This is the first reported occurrence for Pachydiscus arkansanus, Lewyites, Hoploscaphites cf. H. brevis and Discoscaphites from the Coon Creek Formation at its type locality.

@article{openalexw2183535445,
    author = "Larson, Neal L.",
    title = "THE LATE CAMPANIAN (UPPER CRETACEOUS) CEPHALOPOD FAUNA OF THE COON CREEK FORMATION AT THE TYPE LOCALITY",
    year = "2012",
    abstract = "There is an unusually rich, Late Campanian (Upper Cretaceous), molluscan fauna from the Coon Creek Formation at its type locality, 7 1/2 miles north of Adamsville, McNairy County, Tennessee. The ammonite fauna is a typical, late Campanian, Gulf Coast fauna consisting almost entirely of aberrant ammonites and only one tightly coiled, planispiral form. A few authors have published on the fauna from this locality, most notably Bruce Wade, who published on the entire known fauna; Norman Sohl, who published on the gastropods; Cobban and Kennedy who published on the ammonites; and Brister and Young, who published an overview on the fauna and history of Coon Creek at the type locality from the extensive collections made by the Pink Palace Museum. Except for Discoscaphites the ammonite fauna from this locality compares both at a species level and stratigraphically with the fauna from the Nacatoch Sand in Kaufman and Navarro Counties of Texas (Stephenson, 1941). Except for Discoscaphites nearly all of the ammonite fauna also correlates to the Baculites cuneatus through Baculites jenseni Zones of the Pierre and Bearpaw Shales in the Western Interior, most notably to that from the Middle Park and Fort Collins area of Colorado as reported by Kennedy et al. (2000). Because the aragonitic shell of this cephalopod fauna is so well preserved at this locality it makes it possible to give a more complete description of some of the heteromorph ammonite species than had been previously done, most importantly the rib indexes. Both invertebrate and vertebrate researchers have published that the fauna from the type locality of the Coon Creek Formation constitutes a lower Maastrichtian fauna. The presence of Cirroceras conradi, Hoploscaphites reesidei, Solenoceras reesidei, S. texanum, and Nostoceras (Nostoceras) hyatti places the age of the Coon Creek Tongue at the type locality at upper Late Campanian (72-71.5 MYA), the equivalent age of the Baculites reesidei through B. jenseni Zones of the Western Interior. This is the first reported occurrence for Pachydiscus arkansanus, Lewyites, Hoploscaphites cf. H. brevis and Discoscaphites from the Coon Creek Formation at its type locality.",
    openalex = "W2183535445",
    references = "doi1012060003009020002510001lcchaf20co2, doi105962bhltitle19929, kennedy2000late"
}

@article{doi101016jpalaeo201310007,
    author = "Corbett, Matthew J. and Watkins, David K.",
    title = "Calcareous nannofossil paleoecology of the mid-Cretaceous Western Interior Seaway and evidence of oligotrophic surface waters during OAE2",
    year = "2013",
    journal = "Palaeogeography Palaeoclimatology Palaeoecology",
    url = "https://doi.org/10.1016/j.palaeo.2013.10.007",
    doi = "10.1016/j.palaeo.2013.10.007",
    openalex = "W2038552972",
    references = "openalexw1909835793"
}

Rudistids are uncommon fossils in Upper Cretaceous rocks of the Western Interior of the United States. Since 1856 there have been fewer than 40 occurrences noted in the literature, many of these without descriptions or illustrations. Only six of these occurrences are from New Mexico. Therefore, the discovery of two fragments of solitary radiolitid rudistids and one fragment of a small bouquet from a sandy concretionary bed in the lower tongue of Mancos Shale in Lincoln County, New Mexico, is of some importance. Associated fossils in the concretions include the ammonites Spathites rioensis, Morrowites depressus, and Collignoniceras woollgari woollgari, placing the rudistid bed in the lower part of the middle Turonian C. woollgari Zone. Although specifically indeterminate, the rudistids are probably conspecific with a large rudistid bouquet composed of Durania cornupastoris that was described and illustrated from rocks in the same zone in the Greenhorn Limestone of Colorado.

@article{doi1058799nmgv35n113,
    author = "Hook, Stephen C. and Cobban, W. A.",
    title = "Middle Turonian (Late Cretaceous) rudistids from the lower tongue of the Mancos Shale, Lincoln County, New Mexico",
    year = "2013",
    journal = "New Mexico Geology",
    abstract = "Rudistids are uncommon fossils in Upper Cretaceous rocks of the Western Interior of the United States. Since 1856 there have been fewer than 40 occurrences noted in the literature, many of these without descriptions or illustrations. Only six of these occurrences are from New Mexico. Therefore, the discovery of two fragments of solitary radiolitid rudistids and one fragment of a small bouquet from a sandy concretionary bed in the lower tongue of Mancos Shale in Lincoln County, New Mexico, is of some importance. Associated fossils in the concretions include the ammonites Spathites rioensis, Morrowites depressus, and Collignoniceras woollgari woollgari, placing the rudistid bed in the lower part of the middle Turonian C. woollgari Zone. Although specifically indeterminate, the rudistids are probably conspecific with a large rudistid bouquet composed of Durania cornupastoris that was described and illustrated from rocks in the same zone in the Greenhorn Limestone of Colorado.",
    url = "https://doi.org/10.58799/nmg-v35n1.13",
    doi = "10.58799/nmg-v35n1.13",
    openalex = "W2181311407",
    references = "doi103133pp186k"
}

Dating sedimentary carbonates using the U-Pb method can help improve the Phanerozoic timescale. Using a novel combination of laser-ablation, multi-collector, inductively-coupled-plasma, mass-spectrometry (LA–MC–ICP–MS) and thermal ionization multi-collector mass spectrometry (TIMS), U-Pb numerical ages were obtained on early-diagenetic calcite cements in Jurassic ammonites in which concentrations of U range from 0.47 to 5.3 ppm. The calcite cements of two ammonites, IS1 and IS2, from the uppermost Bifrons Zone of the Toarcian (179–180 Ma) of the UK, gave TIMS-normalized LA U–Pb dates of 164.9 ± 5.3 Ma and 166.7 ± 4.8 Ma respectively. Normalizing LA–ICP–MC–MS data to an in-house calcite standard gave a more precise date of 165.5 ± 3.3 Ma for IS1 cement. An unzoned ammonite, SS2, of Bajocian age (168–170 Ma) yield a TIMS-normalized LA U–Pb age of 158.8 ± 4.3 Ma for its early-diagenetic cement. Both the combined LA–MC–ICP–MS and TIMS approach, and the use of a calcite laser ablation standard can result in accurate ages of cements with uncertainties of 2–3% (2σ). The later, however, is more efficient and precise. These U-Pb dates of cements are 10 to 20 Myr younger than the numerical ages of the biostratigraphic intervals from which the ammonites derive. The U-Pb dates are taken to represent the time at which the aragonite shell of the ammonite inverted to calcite and released its U to precipitate in a late-diagenetic alteration of early-diagenetic fringing cements. Concentrations of U and Pb in a range of other pristine biogenic carbonates were found too low (U < 0.01 ppm) for meaningful dating using laser ablation method.

@article{doi101016jchemgeo201403020,
    author = "Li, Q. and Parrish, Randall R. and Horstwood, Matthew and McArthur, J.M.",
    title = "U–Pb dating of cements in Mesozoic ammonites",
    year = "2014",
    journal = "Chemical Geology",
    abstract = "Dating sedimentary carbonates using the U-Pb method can help improve the Phanerozoic timescale. Using a novel combination of laser-ablation, multi-collector, inductively-coupled-plasma, mass-spectrometry (LA–MC–ICP–MS) and thermal ionization multi-collector mass spectrometry (TIMS), U-Pb numerical ages were obtained on early-diagenetic calcite cements in Jurassic ammonites in which concentrations of U range from 0.47 to 5.3 ppm. The calcite cements of two ammonites, IS1 and IS2, from the uppermost Bifrons Zone of the Toarcian (179–180 Ma) of the UK, gave TIMS-normalized LA U–Pb dates of 164.9 ± 5.3 Ma and 166.7 ± 4.8 Ma respectively. Normalizing LA–ICP–MC–MS data to an in-house calcite standard gave a more precise date of 165.5 ± 3.3 Ma for IS1 cement. An unzoned ammonite, SS2, of Bajocian age (168–170 Ma) yield a TIMS-normalized LA U–Pb age of 158.8 ± 4.3 Ma for its early-diagenetic cement. Both the combined LA–MC–ICP–MS and TIMS approach, and the use of a calcite laser ablation standard can result in accurate ages of cements with uncertainties of 2–3\% (2σ). The later, however, is more efficient and precise. These U-Pb dates of cements are 10 to 20 Myr younger than the numerical ages of the biostratigraphic intervals from which the ammonites derive. The U-Pb dates are taken to represent the time at which the aragonite shell of the ammonite inverted to calcite and released its U to precipitate in a late-diagenetic alteration of early-diagenetic fringing cements. Concentrations of U and Pb in a range of other pristine biogenic carbonates were found too low (U < 0.01 ppm) for meaningful dating using laser ablation method.",
    url = "https://doi.org/10.1016/j.chemgeo.2014.03.020",
    doi = "10.1016/j.chemgeo.2014.03.020",
    openalex = "W2018432167",
    references = "doi1010160012821x77900607, doi1010292006gc001492, doi1010292007rg000246, doi101038326865a0, doi101103physrevc41889, doi101111j1751908x1995tb00147x, doi1011270078042120120020, doi1011300091761319880160641cmftoo23co2, doi1034194geusbv14646, openalexw2797914455"
}

@article{doi101016jpalaeo201407002,
    author = "Elderbak, Khalifa and Leckie, R. Mark and Tibert, Neil E.",
    title = "Paleoenvironmental and paleoceanographic changes across the Cenomanian–Turonian Boundary Event (Oceanic Anoxic Event 2) as indicated by foraminiferal assemblages from the eastern margin of the Cretaceous Western Interior Sea",
    year = "2014",
    journal = "Palaeogeography Palaeoclimatology Palaeoecology",
    url = "https://doi.org/10.1016/j.palaeo.2014.07.002",
    doi = "10.1016/j.palaeo.2014.07.002",
    openalex = "W2012386486",
    references = "doi101016jpalaeo200509024, doi101130001676061952631011cotcfo20co2, openalexw1836508436"
}

This study revises and improves the chronostratigraphic framework for late Turonian through early Campanian time based on work in the Western Interior U.S. and introduces new methods to better quantify uncertainties associated with the development of such time scales. Building on the unique attributes of the Western Interior Basin, which contains abundant volcanic ash beds and rhythmic strata interpreted to record orbital cycles, we integrate new radioisotopic data of improved accuracy with a recently published astrochronologic framework for the Niobrara Formation. New 40Ar/39Ar laser fusion ages corresponding to eight different ammonite biozones are determined by analysis of legacy samples, as well as newly collected material. These results are complemented by new U-Pb (zircon) chemical abrasion–isotope dilution–thermal ionization mass spectrometry ages from four biozones in the study interval. When combined with published radioisotopic data from the Cenomanian-Turonian boundary, paired 206Pb/238U and 40Ar/39Ar ages spanning Cenomanian to Campanian time support an astronomically calibrated Fish Canyon sanidine standard age of 28.201 Ma. Stage boundary ages are estimated via integration of new radioisotopic data with the floating astrochronology for the Niobrara Formation. The ages are determined by anchoring the long eccentricity bandpass from spectral analysis of the Niobrara Formation to radioisotopic ages with the lowest uncertainty proximal to the boundary, and adding or subtracting time by parsing the 405 k.y. cycles. The new stage boundary age determinations are: 89.75 ± 0.38 Ma for the Turonian-Coniacian, 86.49 ± 0.44 Ma for the Coniacian-Santonian, and 84.19 ± 0.38 Ma for the Santonian-Campanian boundary. The 2σ uncertainties for these estimates include systematic contributions from the radioisotopic measurements, astrochronologic methods, and geologic uncertainties (related to stratigraphic correlation and the presence of hiatuses). The latter geologic uncertainties have not been directly addressed in prior time scale studies and their determination was made possible by critical biostratigraphic observations. Each methodological approach employed in this study—new radioisotopic analysis, stratigraphic correlation, astrochronology, and ammonite and inoceramid biostratigraphy—was critical for achieving the final result.

@article{doi101130b309291,
    author = "Sageman, Bradley B. and Singer, Brad S. and Meyers, Stephen R. and Siewert, S. E. and Walaszczyk, Ireneusz and Condon, Daniel J. and Jicha, Brian R. and Obradovich, John D. and Sawyer, David A.",
    title = "Integrating 40Ar/39Ar, U-Pb, and astronomical clocks in the Cretaceous Niobrara Formation, Western Interior Basin, USA",
    year = "2014",
    journal = "Geological Society of America Bulletin",
    abstract = "This study revises and improves the chronostratigraphic framework for late Turonian through early Campanian time based on work in the Western Interior U.S. and introduces new methods to better quantify uncertainties associated with the development of such time scales. Building on the unique attributes of the Western Interior Basin, which contains abundant volcanic ash beds and rhythmic strata interpreted to record orbital cycles, we integrate new radioisotopic data of improved accuracy with a recently published astrochronologic framework for the Niobrara Formation. New 40Ar/39Ar laser fusion ages corresponding to eight different ammonite biozones are determined by analysis of legacy samples, as well as newly collected material. These results are complemented by new U-Pb (zircon) chemical abrasion–isotope dilution–thermal ionization mass spectrometry ages from four biozones in the study interval. When combined with published radioisotopic data from the Cenomanian-Turonian boundary, paired 206Pb/238U and 40Ar/39Ar ages spanning Cenomanian to Campanian time support an astronomically calibrated Fish Canyon sanidine standard age of 28.201 Ma. Stage boundary ages are estimated via integration of new radioisotopic data with the floating astrochronology for the Niobrara Formation. The ages are determined by anchoring the long eccentricity bandpass from spectral analysis of the Niobrara Formation to radioisotopic ages with the lowest uncertainty proximal to the boundary, and adding or subtracting time by parsing the 405 k.y. cycles. The new stage boundary age determinations are: 89.75 ± 0.38 Ma for the Turonian-Coniacian, 86.49 ± 0.44 Ma for the Coniacian-Santonian, and 84.19 ± 0.38 Ma for the Santonian-Campanian boundary. The 2σ uncertainties for these estimates include systematic contributions from the radioisotopic measurements, astrochronologic methods, and geologic uncertainties (related to stratigraphic correlation and the presence of hiatuses). The latter geologic uncertainties have not been directly addressed in prior time scale studies and their determination was made possible by critical biostratigraphic observations. Each methodological approach employed in this study—new radioisotopic analysis, stratigraphic correlation, astrochronology, and ammonite and inoceramid biostratigraphy—was critical for achieving the final result.",
    url = "https://doi.org/10.1130/b30929.1",
    doi = "10.1130/b30929.1",
    openalex = "W2162624498",
    references = "cobban1969the, doi1010160012821x77900607, doi101016jchemgeo200503011, doi101016s0009254197001599, doi101016s0016703799002045, doi1010510004636120041335, doi10105100046361201116836, doi101103physrevc41889, doi101109proc198212433, doi101126science1154339, doi102113gselements9119, doi103133ofr20061250, doi103133pp619, openalexw2797914455"
}

Abstract Late Cretaceous carbon isotope curves generated for localities in Europe, Asia, and the deep-sea records have provided the foundation for development of a contiguous, intercontinental chemostratigraphic framework. Despite the development of carbon isotope records from selected stratigraphic intervals in the Western Interior Basin, however, a comprehensive δ13C record comparable to those developed in Europe and Asia, and from ODP sites, had not yet been completed. This study reports a new, high-resolution Cenomanian to Campanian carbon isotope record for the central Western Interior Basin of North America that makes a key contribution to the intercontinental correlation. The curve is correlated to the well-developed molluscan biostratigraphic framework for the Western Interior Basin, as well as a revised geochronology based on integration of new radioisotopic dating and astrochronology developed in the same core records from where the δ13C data were derived. The new δ13C record reflects not only major perturbations in the global carbon cycle, such as the mid-Cenomanian Event and the Cenomanian–Turonian Ocean Anoxic Event 2, but also smaller excursions that have been recognized in records from Europe and Asia. This shows that the Western Interior shallow epeiric sea was not isolated for any appreciable part of Cenomanian to early Campanian time—it consistently recorded changes in the global marine carbon cycle observed elsewhere. A critical attribute of the chemostratigraphic dataset produced in this study is its linkage with a revised Late Cretaceous time scale. Assignment of revised ages to Western Interior carbon isotope events that are globally expressed will allow export of the improved time scale to localities within and outside the Western Interior where similar carbon isotope records have been generated. This chronostratigraphic tool will allow a number of stratigraphic and geochemical hypotheses to be more rigorously tested.

@article{doi102110jsr201438,
    author = "Joo, Young Ji and Sageman, B. B.",
    title = "Cenomanian To Campanian Carbon Isotope Chemostratigraphy from the Western Interior Basin, U.S.A",
    year = "2014",
    journal = "Journal of Sedimentary Research",
    abstract = "Abstract Late Cretaceous carbon isotope curves generated for localities in Europe, Asia, and the deep-sea records have provided the foundation for development of a contiguous, intercontinental chemostratigraphic framework. Despite the development of carbon isotope records from selected stratigraphic intervals in the Western Interior Basin, however, a comprehensive δ13C record comparable to those developed in Europe and Asia, and from ODP sites, had not yet been completed. This study reports a new, high-resolution Cenomanian to Campanian carbon isotope record for the central Western Interior Basin of North America that makes a key contribution to the intercontinental correlation. The curve is correlated to the well-developed molluscan biostratigraphic framework for the Western Interior Basin, as well as a revised geochronology based on integration of new radioisotopic dating and astrochronology developed in the same core records from where the δ13C data were derived. The new δ13C record reflects not only major perturbations in the global carbon cycle, such as the mid-Cenomanian Event and the Cenomanian–Turonian Ocean Anoxic Event 2, but also smaller excursions that have been recognized in records from Europe and Asia. This shows that the Western Interior shallow epeiric sea was not isolated for any appreciable part of Cenomanian to early Campanian time—it consistently recorded changes in the global marine carbon cycle observed elsewhere. A critical attribute of the chemostratigraphic dataset produced in this study is its linkage with a revised Late Cretaceous time scale. Assignment of revised ages to Western Interior carbon isotope events that are globally expressed will allow export of the improved time scale to localities within and outside the Western Interior where similar carbon isotope records have been generated. This chronostratigraphic tool will allow a number of stratigraphic and geochemical hypotheses to be more rigorously tested.",
    url = "https://doi.org/10.2110/jsr.2014.38",
    doi = "10.2110/jsr.2014.38",
    openalex = "W2143504614",
    references = "doi101016jcretres200704006, doi101016jgeobios200411004, doi101130b309291, doi103133ofr20061250, doi1037570bgsd19843313"
}

@article{doi101016jcretres201504010,
    author = "Eldrett, James S and Ma, Chao and Bergman, Steven C. and Lutz, Brendan and Gregory, F. John and Dodsworth, Paul and Phipps, Mark Daniel and Hardas, Petros and Minisini, Daniel and Ozkan, Aysen and Ramezani, Jahander and Bowring, Samuel A. and Kamo, Sandra L. and Ferguson, Kurt M. and Macaulay, C. I. and Kelly, Amy E.",
    title = "An astronomically calibrated stratigraphy of the Cenomanian, Turonian and earliest Coniacian from the Cretaceous Western Interior Seaway, USA: Implications for global chronostratigraphy",
    year = "2015",
    journal = "Cretaceous Research",
    url = "https://doi.org/10.1016/j.cretres.2015.04.010",
    doi = "10.1016/j.cretres.2015.04.010",
    openalex = "W2141401478",
    references = "doi101016s0025322701002894, doi101130b309291"
}

@article{doi101016jcretres201510019,
    author = "Walaszczyk, Ireneusz and Cobban, W. A.",
    title = "Inoceramid bivalves and biostratigraphy of the upper Albian and lower Cenomanian of the United States Western Interior Basin",
    year = "2015",
    journal = "Cretaceous Research",
    url = "https://doi.org/10.1016/j.cretres.2015.10.019",
    doi = "10.1016/j.cretres.2015.10.019",
    openalex = "W2177646960",
    references = "doi1013063d93432e16b111d78645000102c1865d"
}

Abstract The inoceramid bivalves of the genus Mytiloides, from the Turonian (Upper Cretaceous) of the Sredna Gora Mts (north-western Bulgaria), are studied. The material comes from three sections: Izvor, Filipovtsi, and Vrabchov dol. Eight species are described taxonomically, with one left in open nomenclature: M. cf. mytiloides (Mantell, 1822), M. mytiloidiformis (Tröger, 1967), M. incertus (Jimbo, 1894), M. scupini (Heinz, 1930), M. herbichi (Atabekian, 1969), M. striatoconcentricus (Gümbel, 1868), M. labiatoidiformis (Tröger, 1967) and M. carpathicus (Simionescu, 1899). Mytiloides incertus and Mytiloides scupini are index species for the eponymous Upper Turonian inoceramid biozones.

@article{doi101515agp20150004,
    author = "Dochev, Docho",
    title = "Turonian (Upper Cretaceous) inoceramid bivalves of the genus Mytiloides from the Sredna Gora Mountains, north-western Bulgaria",
    year = "2015",
    journal = "Acta Geologica Polonica",
    abstract = "Abstract The inoceramid bivalves of the genus Mytiloides, from the Turonian (Upper Cretaceous) of the Sredna Gora Mts (north-western Bulgaria), are studied. The material comes from three sections: Izvor, Filipovtsi, and Vrabchov dol. Eight species are described taxonomically, with one left in open nomenclature: M. cf. mytiloides (Mantell, 1822), M. mytiloidiformis (Tröger, 1967), M. incertus (Jimbo, 1894), M. scupini (Heinz, 1930), M. herbichi (Atabekian, 1969), M. striatoconcentricus (Gümbel, 1868), M. labiatoidiformis (Tröger, 1967) and M. carpathicus (Simionescu, 1899). Mytiloides incertus and Mytiloides scupini are index species for the eponymous Upper Turonian inoceramid biozones.",
    url = "https://doi.org/10.1515/agp-2015-0004",
    doi = "10.1515/agp-2015-0004",
    openalex = "W744549804",
    references = "doi103133pp1271"
}

ABSTRACT Twenty taxa are described from the Cretaceous of Oman (Adam Foothills). The genera Puzosia, Placenticeras, Cunningtoniceras, Nigericeras, Metoicoceras, Rubroceras and Hoplitoides and the subgenus C. (Gentoniceras) are recorded for the first time from the Arabian Peninsula. Based on the ammonite ranges, a sequence of nine bioevents of the Albian–Turonian is correlated within the zonation, and some markers allow correlations at a larger scale, at least along the southern Neo-Tethys margin. The ammonite data give new constraints for the correlations of the lithological units along the Adam Foothills West-East transect and they question the definition of the lithostratigraphic units within the Natih Formation, especially the Natih A and B members. From a paleogeographic point of view Oman is a landmark for the distribution of the ammonites between the western Neo-Tethys (Europe, North Africa, Middle East) and the eastern Neo-Tethys (Africa, Madagascar and India).

@article{doi102113geoarabia200219,
    author = "Meister, Christian and Piuz, André",
    title = "Cretaceous ammonites from the Sultanate of Oman (Adam Foothills)",
    year = "2015",
    journal = "GeoArabia",
    abstract = "ABSTRACT Twenty taxa are described from the Cretaceous of Oman (Adam Foothills). The genera Puzosia, Placenticeras, Cunningtoniceras, Nigericeras, Metoicoceras, Rubroceras and Hoplitoides and the subgenus C. (Gentoniceras) are recorded for the first time from the Arabian Peninsula. Based on the ammonite ranges, a sequence of nine bioevents of the Albian–Turonian is correlated within the zonation, and some markers allow correlations at a larger scale, at least along the southern Neo-Tethys margin. The ammonite data give new constraints for the correlations of the lithological units along the Adam Foothills West-East transect and they question the definition of the lithostratigraphic units within the Natih Formation, especially the Natih A and B members. From a paleogeographic point of view Oman is a landmark for the distribution of the ammonites between the western Neo-Tethys (Europe, North Africa, Middle East) and the eastern Neo-Tethys (Africa, Madagascar and India).",
    url = "https://doi.org/10.2113/geoarabia200219",
    doi = "10.2113/geoarabia200219",
    openalex = "W3080587363",
    references = "cobban1971new"
}

@article{doi101007s1251701627141,
    author = "Meister, Christian and Piuz, André and Cavin, Lionel and Boudad, Larbi and Bacchia, Flavio and Ettachfini, El Mostafa and Benyoucef, Madani",
    title = "Late Cretaceous (Cenomanian-Turonian) ammonites from southern Morocco and south western Algeria",
    year = "2016",
    journal = "Arabian Journal of Geosciences",
    url = "https://doi.org/10.1007/s12517-016-2714-1",
    doi = "10.1007/s12517-016-2714-1",
    openalex = "W2565398137",
    references = "doi105962bhltitle45918, openalexw2221217307, openalexw2595223531"
}

Interbasinal stratigraphic correlation provides the foundation for all consequent continental-scale geological and paleontological analyses. Correlation requires synthesis of lithostratigraphic, biostratigraphic and geochronologic data, and must be periodically updated to accord with advances in dating techniques, changing standards for radiometric dates, new stratigraphic concepts, hypotheses, fossil specimens, and field data. Outdated or incorrect correlation exposes geological and paleontological analyses to potential error. The current work presents a high-resolution stratigraphic chart for terrestrial Late Cretaceous units of North America, combining published chronostratigraphic, lithostratigraphic, and biostratigraphic data. 40Ar / 39Ar radiometric dates are newly recalibrated to both current standard and decay constant pairings. Revisions to the stratigraphic placement of most units are slight, but important changes are made to the proposed correlations of the Aguja and Javelina formations, Texas, and recalibration corrections in particular affect the relative age positions of the Belly River Group, Alberta; Judith River Formation, Montana; Kaiparowits Formation, Utah; and Fruitland and Kirtland formations, New Mexico. The stratigraphic ranges of selected clades of dinosaur species are plotted on the chronostratigraphic framework, with some clades comprising short-duration species that do not overlap stratigraphically with preceding or succeeding forms. This is the expected pattern that is produced by an anagenetic mode of evolution, suggesting that true branching (speciation) events were rare and may have geographic significance. The recent hypothesis of intracontinental latitudinal provinciality of dinosaurs is shown to be affected by previous stratigraphic miscorrelation. Rapid stepwise acquisition of display characters in many dinosaur clades, in particular chasmosaurine ceratopsids, suggests that they may be useful for high resolution biostratigraphy.

@article{doi101371journalpone0188426,
    author = "Fowler, Denver Warwick",
    title = "Revised geochronology, correlation, and dinosaur stratigraphic ranges of the Santonian-Maastrichtian (Late Cretaceous) formations of the Western Interior of North America.",
    year = "2017",
    journal = "PloS one",
    abstract = "Interbasinal stratigraphic correlation provides the foundation for all consequent continental-scale geological and paleontological analyses. Correlation requires synthesis of lithostratigraphic, biostratigraphic and geochronologic data, and must be periodically updated to accord with advances in dating techniques, changing standards for radiometric dates, new stratigraphic concepts, hypotheses, fossil specimens, and field data. Outdated or incorrect correlation exposes geological and paleontological analyses to potential error. The current work presents a high-resolution stratigraphic chart for terrestrial Late Cretaceous units of North America, combining published chronostratigraphic, lithostratigraphic, and biostratigraphic data. 40Ar / 39Ar radiometric dates are newly recalibrated to both current standard and decay constant pairings. Revisions to the stratigraphic placement of most units are slight, but important changes are made to the proposed correlations of the Aguja and Javelina formations, Texas, and recalibration corrections in particular affect the relative age positions of the Belly River Group, Alberta; Judith River Formation, Montana; Kaiparowits Formation, Utah; and Fruitland and Kirtland formations, New Mexico. The stratigraphic ranges of selected clades of dinosaur species are plotted on the chronostratigraphic framework, with some clades comprising short-duration species that do not overlap stratigraphically with preceding or succeeding forms. This is the expected pattern that is produced by an anagenetic mode of evolution, suggesting that true branching (speciation) events were rare and may have geographic significance. The recent hypothesis of intracontinental latitudinal provinciality of dinosaurs is shown to be affected by previous stratigraphic miscorrelation. Rapid stepwise acquisition of display characters in many dinosaur clades, in particular chasmosaurine ceratopsids, suggests that they may be useful for high resolution biostratigraphy.",
    url = "https://pmc.ncbi.nlm.nih.gov/articles/PMC5699823/",
    doi = "10.1371/journal.pone.0188426",
    openalex = "W2544476050",
    pmcid = "PMC5699823",
    pmid = "29166406",
    references = "doi1010160012821x77900607, doi101016016896228790025x, doi101016037594749090598g, doi101016jgca201006017, doi101016jgca201106021, doi101016jsedgeo200610001, doi101016s0009254197001599, doi101016s0016703799002045, doi101016s0375947497006131, doi101126science1154339, doi101130001676061952631011cotcfo20co2, doi101130b310761, doi101139e93016, doi101371journalpone0012292, doi101371journalpone0024487, doi101371journalpone0025186, doi101371journalpone0141304, doi10167102724634200727373aarolm20co2, doi105860choice514447, lehman1987late, openalexw2025327988"
}

Abstract The present contribution deals with the taxonomy of seven species of perisphinctoid ammonite from the Štramberk Limestone (Outer Western Carpathians, Czech Republic) deposited in Moravian-Silesian museums. The age of these studied ammonites is compared with that of index microfossils contained in the matrix adhering to or infilling the studied specimens. The ammonites document a stratigraphic range from earliest Tithonian to early Berriasian. In addition to taxonomy and new ontogenetic data on some species, we also present data on their palaeogeographic distribution. The occurrence of Subboreal himalayitids in the Štramberk Limestone of an early Berriasian age is determined by both the microfauna and accompanying ammonites, which indicate connection of the Silesian-part of the Tethyan Carpathian area with the Subboreal Russian Platform Basin. These records also suggest an early Berriasian age (Jacobi Chron) for the lowermost part of the Ryazanian stage in its type area.

@article{doi101515geoca20170038,
    author = "Vašíček, Zdeněk and Reháková, Daniela and Skupien, Petr",
    title = "Some perisphinctoid ammonites of the Štramberk Limestone and their dating with associated microfossils (Tithonian to Lower Berriasian, Outer Western Carpathians, Czech Republic)",
    year = "2017",
    journal = "Geologica Carpathica",
    abstract = "Abstract The present contribution deals with the taxonomy of seven species of perisphinctoid ammonite from the Štramberk Limestone (Outer Western Carpathians, Czech Republic) deposited in Moravian-Silesian museums. The age of these studied ammonites is compared with that of index microfossils contained in the matrix adhering to or infilling the studied specimens. The ammonites document a stratigraphic range from earliest Tithonian to early Berriasian. In addition to taxonomy and new ontogenetic data on some species, we also present data on their palaeogeographic distribution. The occurrence of Subboreal himalayitids in the Štramberk Limestone of an early Berriasian age is determined by both the microfauna and accompanying ammonites, which indicate connection of the Silesian-part of the Tethyan Carpathian area with the Subboreal Russian Platform Basin. These records also suggest an early Berriasian age (Jacobi Chron) for the lowermost part of the Ryazanian stage in its type area.",
    url = "https://doi.org/10.1515/geoca-2017-0038",
    doi = "10.1515/geoca-2017-0038",
    openalex = "W2771377458",
    references = "doi101016jcretres201603005"
}

Abstract Microfacies and high resolution studies at the Kurovice quarry (Czech Republic, Outer Western Carpathians) on calpionellids, calcareous and non-calcareous dinoflagellate cysts, sporomorphs and calcareous nannofossils, aligned with paleomagnetism, allow construction of a detailed stratigraphy and paleoenvironmental interpretation across the Jurassic/Cretaceous (J/K) boundary. The Kurovice section consists of allodapic and micrite limestones and marlstones. Identified standard microfacies types SMF 2, SMF 3 and SMF 4 indicate that sediments were deposited on a deep shelf margin (FZ 3), with a change, later, into distal basin conditions and sediments (FZ 1). The sequence spans a stratigraphic range from the Early Tithonian calcareous dinoflagellate Malmica Zone, nannoplankton zone NJT 15 and magnetozone M 21r to the late Early Berriasian calpionellid Elliptica Subzone of the Calpionella Zone, nannoplankton NK-1 Zone and M 17r magnetozone. The J/K boundary is marked by a quantitative increase of small forms of Calpionella alpina, the base of the Alpina Subzone (that corresponds to NJT 17b and M 19n.2n) and by the rare occurrence of Nannoconus wintereri. Palynomorphs include Early Berriasian terrestrial elements — non-calcareous dinoflagellate cysts Achomosphaera neptunii, Prolixosphaeridium sp. A and Tehamadinium evittii. The depositional area for Kurovice was situated at the margin of the NW Tethys. The influence of cold waters from northern latitudes and potential upwellings is highlighted by: 1) the high proportion of radiolarians and sponge spicules, 2) rare calpionellids represented mostly by hyaline forms, 3) the absence of microgranular calpionellids — chitinoidellids, 4) the small percentage of the genera Nannoconus, Polycostella and Conusphaera in nannofossil assemblages, as compared to other sites in Tethys, 5) scarce Nannoconus compressus, which has otherwise been mentioned from the Atlantic area.

@article{doi102478geoca20190009,
    author = "Svobodová, Andrea and Švábenická, Lilian and Reháková, Daniela and Svobodová, Marcela and Skupien, Petr and Elbra, Tiiu and Schnabl, Petr",
    title = "The Jurassic/Cretaceous boundary and high resolution biostratigraphy of the pelagic sequences of the kurovice section (Outer Western Carpathians, the northern Tethyan margin)",
    year = "2019",
    journal = "Geologica Carpathica",
    abstract = "Abstract Microfacies and high resolution studies at the Kurovice quarry (Czech Republic, Outer Western Carpathians) on calpionellids, calcareous and non-calcareous dinoflagellate cysts, sporomorphs and calcareous nannofossils, aligned with paleomagnetism, allow construction of a detailed stratigraphy and paleoenvironmental interpretation across the Jurassic/Cretaceous (J/K) boundary. The Kurovice section consists of allodapic and micrite limestones and marlstones. Identified standard microfacies types SMF 2, SMF 3 and SMF 4 indicate that sediments were deposited on a deep shelf margin (FZ 3), with a change, later, into distal basin conditions and sediments (FZ 1). The sequence spans a stratigraphic range from the Early Tithonian calcareous dinoflagellate Malmica Zone, nannoplankton zone NJT 15 and magnetozone M 21r to the late Early Berriasian calpionellid Elliptica Subzone of the Calpionella Zone, nannoplankton NK-1 Zone and M 17r magnetozone. The J/K boundary is marked by a quantitative increase of small forms of Calpionella alpina, the base of the Alpina Subzone (that corresponds to NJT 17b and M 19n.2n) and by the rare occurrence of Nannoconus wintereri. Palynomorphs include Early Berriasian terrestrial elements — non-calcareous dinoflagellate cysts Achomosphaera neptunii, Prolixosphaeridium sp. A and Tehamadinium evittii. The depositional area for Kurovice was situated at the margin of the NW Tethys. The influence of cold waters from northern latitudes and potential upwellings is highlighted by: 1) the high proportion of radiolarians and sponge spicules, 2) rare calpionellids represented mostly by hyaline forms, 3) the absence of microgranular calpionellids — chitinoidellids, 4) the small percentage of the genera Nannoconus, Polycostella and Conusphaera in nannofossil assemblages, as compared to other sites in Tethys, 5) scarce Nannoconus compressus, which has otherwise been mentioned from the Atlantic area.",
    url = "https://doi.org/10.2478/geoca-2019-0009",
    doi = "10.2478/geoca-2019-0009",
    openalex = "W2937186026",
    references = "doi101515agp20160008"
}

The present contribution provides a taxonomic reassessment of the Lower Cretaceous ammonite species Ammonites crassicostatus d'Orbigny (type species of Colombiceras Spath) and Ammonites gargasensis d'Orbigny (type species of Gargasiceras Casey) from the Aptian-type area (Apt, Vaucluse, southeastern France). Those nominal species represent two ornamental poles of a single population, here referred to C. crassicostatum. The genus Gargasiceras is, therefore, synonymised with Colombiceras. Implications on the taxonomy at the specific, generic, and supra-generic levels are discussed.

@article{doi1022201igl05437652e202091182,
    author = "Frau, Camille and Pictet, Antoine and Caïssa, Mathieu",
    title = "affinities between the Lower Cretaceous Ammonoidea Ammonites crassicostatus d'Orbigny, 1841 and Ammonites gargasensis d'Orbigny, 1841",
    year = "2020",
    journal = "Paleontología mexicana.",
    abstract = "The present contribution provides a taxonomic reassessment of the Lower Cretaceous ammonite species Ammonites crassicostatus d'Orbigny (type species of Colombiceras Spath) and Ammonites gargasensis d'Orbigny (type species of Gargasiceras Casey) from the Aptian-type area (Apt, Vaucluse, southeastern France). Those nominal species represent two ornamental poles of a single population, here referred to C. crassicostatum. The genus Gargasiceras is, therefore, synonymised with Colombiceras. Implications on the taxonomy at the specific, generic, and supra-generic levels are discussed.",
    url = "https://doi.org/10.22201/igl.05437652e.2020.9.1.182",
    doi = "10.22201/igl.05437652e.2020.9.1.182",
    openalex = "W3082472477",
    references = "doi101016jsedgeo201708003"
}

New palaeontological and biostratigraphic data from the Cenomanian–Turonian deposits of the western Saharan Atlas are presented in this study. More than 300 specimens of ammonites were collected from Kebeur es Seguia and Aïn El Orak sections, representing the Rhoundjaïa Formation. With the exception of the three ammonites previously described from the western Saharan Atlas by former authors [namely Neolobites vibrayeanus (d’Orbigny), Vascoceras gamai Choffat and Vascoceras cauvini Chudeau], nine additional ammonite species [Calycoceras (Calycoceras) cf. naviculare (Mantell), Eucalycoceras cf. pentagonum (Jukes-Brown), Metoicoceras geslinianum (d’Orbigny), Nigericeras gadeni (Chudeau), Fikaites subtuberculatus (Collignon), Pseudaspidoceras pseudonodosoides (Choffat), Fagesia peroni Pervinquière, Fagesia tevesthensis (Peron) and Choffaticeras (Choffaticeras) sinaiticum (Douvillé)] are described and illustrated from the studied area. Biostratigraphic analysis revealed four ammonite biozones; three from the late Cenomanian namely, the Neolobites vibrayeanus Total Range Zone, the Metoicoceras geslinianum Total Range Zone and the Vascoceras cauvini Total Range Zone; and one from the early Turonian (earliest Turonian), the Choffaticeras sinaiticum Total Range Zone. The recognised ammonite zones demonstrate a significant palaeobiogeographical relationship between the studied area and other countries of North Africa, the Middle East, South America and southern Europe.

@article{doi1010800891296320212003352,
    author = "Guendouz, Mohamed Lassad and Zaoui, Djamila and Benyoucef, Madani and Qot, Gamal El and Meister, Christian and Piuz, André and Bensalah, Mustapha",
    title = "Late Cenomanian–early Turonian ammonites from the Western Saharan Atlas (Algeria)",
    year = "2022",
    journal = "Historical Biology",
    abstract = "New palaeontological and biostratigraphic data from the Cenomanian–Turonian deposits of the western Saharan Atlas are presented in this study. More than 300 specimens of ammonites were collected from Kebeur es Seguia and Aïn El Orak sections, representing the Rhoundjaïa Formation. With the exception of the three ammonites previously described from the western Saharan Atlas by former authors [namely Neolobites vibrayeanus (d’Orbigny), Vascoceras gamai Choffat and Vascoceras cauvini Chudeau], nine additional ammonite species [Calycoceras (Calycoceras) cf. naviculare (Mantell), Eucalycoceras cf. pentagonum (Jukes-Brown), Metoicoceras geslinianum (d’Orbigny), Nigericeras gadeni (Chudeau), Fikaites subtuberculatus (Collignon), Pseudaspidoceras pseudonodosoides (Choffat), Fagesia peroni Pervinquière, Fagesia tevesthensis (Peron) and Choffaticeras (Choffaticeras) sinaiticum (Douvillé)] are described and illustrated from the studied area. Biostratigraphic analysis revealed four ammonite biozones; three from the late Cenomanian namely, the Neolobites vibrayeanus Total Range Zone, the Metoicoceras geslinianum Total Range Zone and the Vascoceras cauvini Total Range Zone; and one from the early Turonian (earliest Turonian), the Choffaticeras sinaiticum Total Range Zone. The recognised ammonite zones demonstrate a significant palaeobiogeographical relationship between the studied area and other countries of North Africa, the Middle East, South America and southern Europe.",
    url = "https://doi.org/10.1080/08912963.2021.2003352",
    doi = "10.1080/08912963.2021.2003352",
    openalex = "W4214921243",
    references = "doi105962bhltitle38908, openalexw2221217307"
}

The 7th meeting of the IUGS Lower Cretaceous Ammonite Working Group the ‘Kilian Group (KG)’ was held in Warsaw, Poland, in 21st August 2022. Need of major changes for the Jurassic/Cretaceous transition, namely to the uppermost Tithonian and lower Berriasian, and for the upper Aptian and Albian schemes is a long–known issue, which are finally conceptualized and hereby introduced into the Standard Mediterranean Ammonite Zonation (SMAZ, Western Tethys). Besides, refinements were added to the Valanginian and Hauterivian stages, discussion on some zonal indices and units are also provided. The KG highlights again the exclusive use of interval zones and subzones. Most important changes of the uppermost Tithonian–Berriasian stages are the followings: i) use of two folded Berriasian is agreed, to be in better accordance with ammonite turnovers and microfossil framework; ii) uppermost Tithonian Lopeziceras chaperi, top–uppermost Tithonian to lowermost Berriasian Praedalmasiceras progenitor and lower Berriasian Pseudosublanites grandis Zones are accepted to be introduced into the SMAZ, these three zones to cover the former ‘Berriasella’ jacobi Zone auctorum which is formally abandoned; iii) lower Berriasian Delphinella delphinensis Subzone is accepted as a reliable marker level of the upper Praedalmasiceras progenitor Zone; iv) Strambergella jacobi Zone is established and discussed. Tirnovella occitanica Zone and Tirnovella subalpina Subzone are discussed. Modifications on the Valanginian zonation are the followings: i) Neocomites premolicus Subzone is re–defined, ii) Neolissoceras (Vergoliceras) salinarium Subzone is introduced; iii) Neocomites neocomiensiformis Zone is divided into two subzones, the lower N. neocomiensiformis and the upper Busnardoites campylotoxus Subzones. Modifications on the Hauterivian stage are the followings: i) all horizons are deleted; ii) Olcostephanus (Olcostephanus) variegatus Subzone is introduced; iii) Balearites angulicostatus Subzone is introduced; iv) all subzonal index–species of the B. balearis Zone are assigned to genus Balearites; v) Pseudothurmannia mortilleti is considered as a senior synonym of P. catulloi, therefore its nominal subzone also changed its name to mortilleti. No change in the Barremian scheme, however the base of Toxancyloceras vandenheckii Subzone and Zone is defined by the first appearance of the genus Toxancyloceras. Most important changes of the upper Aptian zonation are the followings: i) Nolaniceras nolani and Hypacanthoplites jacobi zones are retained from the SMAZ; ii) re–introduction of Diadochoceras nodosocostatum Zone is given. For the Aptian–Albian transition interval, introduction of ‘Hypacanthoplites’ elegans Zone is accepted, where the Aptian/Albian boundary lies within. Most important zonal changes of the Albian stage are: i) the Leymeriella−based succession is abandoned from the SMAZ and replaced by the cosmopolitan Douvilleiceras−based succession; ii) Douvilleiceras leightonense Zone is introduced; iii) middle Albian Hoplites dentatus, Euhoplites loricatus, Euhoplites lautus zones and Hoplites spathi Subzone are retained from the SMAZ and restricted to the Boreal ammonite scheme; iv) Lyelliceras lyelli Subzone arisen to zonal rank defining the basal middle Albian; v) Oxytropidoceras (Oxytropidoceras) roissyanum Zone is introduced; vi) upper Albian zonation based on the phyletic lineage of Mortoniceratids is kept, however generic names of the indices are modified to Pervinquieria; vii) Pervinquieria pricei Zone is divided into three subzones of Hysteroceras varicosum, H. binum and H. choffati from the oldest to youngest; viii) Pervinquieria inflata Zone is divided into two subzones of Hysteroceras bucklandi and Cantabrigites spp. The KG tributes to our recently deceased ammonitologist colleagues in the Supplement, a discussion on the future work is provided. The next Kilian Group meeting will be held in Hannover, prior to the first day of the 12th International Symposium on the Cretaceous System.

@article{doi101016jcretres2023105716,
    author = "Szives, Ottilia and Moreno-Bedmar, Josep Antón and Aguirre‐Urreta, Beatriz and Frau, Camille and López‐Horgue, Mikel A. and Pictet, Antoine and Ploch, Izabela and Salazar, Christian and Barragán, Ricardo and Latil, Jean‐Louis and Lehmann, Jens and Robert, Emmanuel and Reboulet, Stéphane",
    title = "Report on the 7th International Meeting of the IUGS Lower Cretaceous Ammonite Working Group, the Kilian Group (Warsaw, Poland, 21st August 2022): State of the art on the current Standard Ammonite Zonation of the Western Tethyan Mediterranean Province",
    year = "2023",
    journal = "Cretaceous Research",
    abstract = "The 7th meeting of the IUGS Lower Cretaceous Ammonite Working Group the ‘Kilian Group (KG)’ was held in Warsaw, Poland, in 21st August 2022. Need of major changes for the Jurassic/Cretaceous transition, namely to the uppermost Tithonian and lower Berriasian, and for the upper Aptian and Albian schemes is a long–known issue, which are finally conceptualized and hereby introduced into the Standard Mediterranean Ammonite Zonation (SMAZ, Western Tethys). Besides, refinements were added to the Valanginian and Hauterivian stages, discussion on some zonal indices and units are also provided. The KG highlights again the exclusive use of interval zones and subzones. Most important changes of the uppermost Tithonian–Berriasian stages are the followings: i) use of two folded Berriasian is agreed, to be in better accordance with ammonite turnovers and microfossil framework; ii) uppermost Tithonian Lopeziceras chaperi, top–uppermost Tithonian to lowermost Berriasian Praedalmasiceras progenitor and lower Berriasian Pseudosublanites grandis Zones are accepted to be introduced into the SMAZ, these three zones to cover the former ‘Berriasella’ jacobi Zone auctorum which is formally abandoned; iii) lower Berriasian Delphinella delphinensis Subzone is accepted as a reliable marker level of the upper Praedalmasiceras progenitor Zone; iv) Strambergella jacobi Zone is established and discussed. Tirnovella occitanica Zone and Tirnovella subalpina Subzone are discussed. Modifications on the Valanginian zonation are the followings: i) Neocomites premolicus Subzone is re–defined, ii) Neolissoceras (Vergoliceras) salinarium Subzone is introduced; iii) Neocomites neocomiensiformis Zone is divided into two subzones, the lower N. neocomiensiformis and the upper Busnardoites campylotoxus Subzones. Modifications on the Hauterivian stage are the followings: i) all horizons are deleted; ii) Olcostephanus (Olcostephanus) variegatus Subzone is introduced; iii) Balearites angulicostatus Subzone is introduced; iv) all subzonal index–species of the B. balearis Zone are assigned to genus Balearites; v) Pseudothurmannia mortilleti is considered as a senior synonym of P. catulloi, therefore its nominal subzone also changed its name to mortilleti. No change in the Barremian scheme, however the base of Toxancyloceras vandenheckii Subzone and Zone is defined by the first appearance of the genus Toxancyloceras. Most important changes of the upper Aptian zonation are the followings: i) Nolaniceras nolani and Hypacanthoplites jacobi zones are retained from the SMAZ; ii) re–introduction of Diadochoceras nodosocostatum Zone is given. For the Aptian–Albian transition interval, introduction of ‘Hypacanthoplites’ elegans Zone is accepted, where the Aptian/Albian boundary lies within. Most important zonal changes of the Albian stage are: i) the Leymeriella−based succession is abandoned from the SMAZ and replaced by the cosmopolitan Douvilleiceras−based succession; ii) Douvilleiceras leightonense Zone is introduced; iii) middle Albian Hoplites dentatus, Euhoplites loricatus, Euhoplites lautus zones and Hoplites spathi Subzone are retained from the SMAZ and restricted to the Boreal ammonite scheme; iv) Lyelliceras lyelli Subzone arisen to zonal rank defining the basal middle Albian; v) Oxytropidoceras (Oxytropidoceras) roissyanum Zone is introduced; vi) upper Albian zonation based on the phyletic lineage of Mortoniceratids is kept, however generic names of the indices are modified to Pervinquieria; vii) Pervinquieria pricei Zone is divided into three subzones of Hysteroceras varicosum, H. binum and H. choffati from the oldest to youngest; viii) Pervinquieria inflata Zone is divided into two subzones of Hysteroceras bucklandi and Cantabrigites spp. The KG tributes to our recently deceased ammonitologist colleagues in the Supplement, a discussion on the future work is provided. The next Kilian Group meeting will be held in Hannover, prior to the first day of the 12th International Symposium on the Cretaceous System.",
    url = "https://doi.org/10.1016/j.cretres.2023.105716",
    doi = "10.1016/j.cretres.2023.105716",
    openalex = "W4387167465",
    references = "doi101515agp20160008"
}

Upper Cretaceous ammonites are described from six horizons in the mammal-bearing terrigenous-clastic sequences of western Uzbekistan, as follows: Upper Cenomanian, with Placenticeras sp. juv. cf. cumminsi Cragin, 1893 and Metoicoceras geslinianum (d’Orbigny, 1850); Lower Turonian with Tragodesmoceras cf. mauryae Kennedy and Wright, 1981, Placenticeras kharesmense (Lahusen, 1884), Watinoceras coloradoense (Henderson, 1908), Watinoceras amudariense (Arkhangelsky, 1916b), Metasigaloceras rusticum (J. Sowerby, 1823), Morrowites wingi (Morrow, 1935), Sciponoceras cf. bohemicum bohemicum (Fritsch, 1872), and Yezoites amudariensis (Arkhangelsky, 1916b); Middle Turonian with Collignoniceras woollgari woollgari (Mantell, 1822); Upper Turonian with Lewesiceras mantelli (Wright and Wright, 1951) and Placenticeras crassum Ilyin, 2020; a single Placenticeras semiornatum (d’Orbigny, 1850) from around the Coniacian/Santonian boundary, and Santonian Placenticeras polyopsis (Dujardin, 1837).

@article{doi1024425agp2023145619,
    author = "Ward, David J. and King, Chris and Morris, Noel J. and Kennedy, William J.",
    title = "On some Upper Cretaceous ammonites from western Uzbekistan",
    year = "2023",
    journal = "Acta Geologica Polonica",
    abstract = "Upper Cretaceous ammonites are described from six horizons in the mammal-bearing terrigenous-clastic sequences of western Uzbekistan, as follows: Upper Cenomanian, with Placenticeras sp. juv. cf. cumminsi Cragin, 1893 and Metoicoceras geslinianum (d’Orbigny, 1850); Lower Turonian with Tragodesmoceras cf. mauryae Kennedy and Wright, 1981, Placenticeras kharesmense (Lahusen, 1884), Watinoceras coloradoense (Henderson, 1908), Watinoceras amudariense (Arkhangelsky, 1916b), Metasigaloceras rusticum (J. Sowerby, 1823), Morrowites wingi (Morrow, 1935), Sciponoceras cf. bohemicum bohemicum (Fritsch, 1872), and Yezoites amudariensis (Arkhangelsky, 1916b); Middle Turonian with Collignoniceras woollgari woollgari (Mantell, 1822); Upper Turonian with Lewesiceras mantelli (Wright and Wright, 1951) and Placenticeras crassum Ilyin, 2020; a single Placenticeras semiornatum (d’Orbigny, 1850) from around the Coniacian/Santonian boundary, and Santonian Placenticeras polyopsis (Dujardin, 1837).",
    url = "https://doi.org/10.24425/agp.2023.145619",
    doi = "10.24425/agp.2023.145619",
    openalex = "W4386830611",
    references = "openalexw656711665"
}

Slim Buttes is a 30 km long by 10 km wide set of buttes containing Paleogene strata in northwest South Dakota. At Reva Gap in northern Slim Buttes, Eocene-Oligocene terrestrial strata of Chadron and Brule Formations of the White River Group unconformably overlie the Paleocene Fort Union Formation. An angular unconformity separates the White River Group from overlying Oligocene and Miocene strata of the Arikaree Group. Using detrital zircon U-Pb ages, we determine the provenance of these rocks as part of a broader synthesis of post-Laramide sedimentation in the Rocky Mountains and western Great Plains. The Chadron Formation age spectrum is dominated by Cretaceous and Proterozoic grains that are interpreted to be locally recycled from the underlying Cretaceous and Paleocene strata. The Brule Formation has a maximum depositional age of ~34 Ma; Paleogene zircons dominate the age spectrum, and a wide variety of older zircons are also present. The Oligocene zircons are interpreted to have been sourced from volcanic systems in the Great Basin to the southwest, while the subsequent proportions of the zircons were derived from a variety of source areas in the Nevadaplano and Rocky Mountain areas to the southwest. Sparse amounts of Archean zircons are thought to represent the burial of Laramide uplifts throughout Wyoming at the time of Brule deposition, making for a regional paleotopography with little relief across the western interior of the United States. The Miocene-age Arikaree Group sand has a maximum depositional age of ~26 Ma and a multimodal detrital zircon age spectrum. The Arikaree Group provenance likely represents continued sourcing in the Great Basin volcanic systems and Nevadaplano, the beginnings of the re-exhumation of Laramide basement uplifts, and subsequent sediment evacuation out of the western interior and into the Gulf of Mexico to the southeast. Our findings indicate that the transport process and detrital zircon provenance signatures of these strata are decoupled, and each have their own independent evolution. The volcanic signature is primarily transported via aeolian processes (i.e. volcanic ash), and the recycled detrital zircon signature is primarily transported via fluvial processes.

@article{doi102110001c123596,
    author = "Moll, Joseph and Maher, Harmon and Malone, Joshua A. and Malone, David M. and Craddock, John P.",
    title = "Provenance of Paleogene Strata at Slim Buttes, South Dakota: Implications for post-Laramide Evolution of Western Laurentia",
    year = "2024",
    journal = "The Sedimentary Record",
    abstract = "Slim Buttes is a 30 km long by 10 km wide set of buttes containing Paleogene strata in northwest South Dakota. At Reva Gap in northern Slim Buttes, Eocene-Oligocene terrestrial strata of Chadron and Brule Formations of the White River Group unconformably overlie the Paleocene Fort Union Formation. An angular unconformity separates the White River Group from overlying Oligocene and Miocene strata of the Arikaree Group. Using detrital zircon U-Pb ages, we determine the provenance of these rocks as part of a broader synthesis of post-Laramide sedimentation in the Rocky Mountains and western Great Plains. The Chadron Formation age spectrum is dominated by Cretaceous and Proterozoic grains that are interpreted to be locally recycled from the underlying Cretaceous and Paleocene strata. The Brule Formation has a maximum depositional age of \textasciitilde 34 Ma; Paleogene zircons dominate the age spectrum, and a wide variety of older zircons are also present. The Oligocene zircons are interpreted to have been sourced from volcanic systems in the Great Basin to the southwest, while the subsequent proportions of the zircons were derived from a variety of source areas in the Nevadaplano and Rocky Mountain areas to the southwest. Sparse amounts of Archean zircons are thought to represent the burial of Laramide uplifts throughout Wyoming at the time of Brule deposition, making for a regional paleotopography with little relief across the western interior of the United States. The Miocene-age Arikaree Group sand has a maximum depositional age of \textasciitilde 26 Ma and a multimodal detrital zircon age spectrum. The Arikaree Group provenance likely represents continued sourcing in the Great Basin volcanic systems and Nevadaplano, the beginnings of the re-exhumation of Laramide basement uplifts, and subsequent sediment evacuation out of the western interior and into the Gulf of Mexico to the southeast. Our findings indicate that the transport process and detrital zircon provenance signatures of these strata are decoupled, and each have their own independent evolution. The volcanic signature is primarily transported via aeolian processes (i.e. volcanic ash), and the recycled detrital zircon signature is primarily transported via fluvial processes.",
    url = "https://doi.org/10.2110/001c.123596",
    doi = "10.2110/001c.123596",
    openalex = "W4403180679",
    references = "doi1011302021255503"
}

Ammonoid anatomy is still poorly known and every new record of a specimen with soft tissue-preservation yields valuable information. In view of the impressive morphological disparity of ammonoids, we can also expect some disparity in soft tissue anatomy. Here, we present a new specimen from the Kimmeridgian of the Solnhofen region. In contrast to a recently described isolated soft body preserving the male reproductive organs, the new specimen for the first time shows a structure, which we interpret as the ovaries of the female containing immature eggs and further organs. These two specimens are of great importance for sexing ammonoids and for estimating fecundity. The high reproductive rate of Jurassic ammonites underlines their great abundance and the important role of juvenile ammonoids at the base of Devonian to Cretaceous food webs.

@article{doi101038s4159802523299y,
    author = "Klug, Christian and Schweigert, Günter and Lauer, René and Lauer, Bruce and Fuchs, Dirk and Terakado, Kan and Tajika, Amane",
    title = "Reproductive biology and anatomy of ammonites.",
    year = "2025",
    journal = "Scientific reports",
    abstract = "Ammonoid anatomy is still poorly known and every new record of a specimen with soft tissue-preservation yields valuable information. In view of the impressive morphological disparity of ammonoids, we can also expect some disparity in soft tissue anatomy. Here, we present a new specimen from the Kimmeridgian of the Solnhofen region. In contrast to a recently described isolated soft body preserving the male reproductive organs, the new specimen for the first time shows a structure, which we interpret as the ovaries of the female containing immature eggs and further organs. These two specimens are of great importance for sexing ammonoids and for estimating fecundity. The high reproductive rate of Jurassic ammonites underlines their great abundance and the important role of juvenile ammonoids at the base of Devonian to Cretaceous food webs.",
    url = "https://pmc.ncbi.nlm.nih.gov/articles/PMC12612051/",
    doi = "10.1038/s41598-025-23299-y",
    openalex = "W4416148652",
    pmcid = "PMC12612051",
    pmid = "41224991",
    references = "doi101002bies201100001, doi1010079789401796309, doi101007bf02998547, doi101111j14754983201201196x, doi101111j15585646201101567x, doi101111pala12254, doi101111pala12267, doi101126science1198793, doi10112700777749200702450117, doi101127sdgg8320145"
}

@misc{andpangNonetectonic,
    author = "Pang, Ming",
    title = "Tectonic Subsidence of the Cretaceous Western Interior Basin, United States.",
    year = "None",
    url = "https://doi.org/10.31390/gradschool\_disstheses.5926",
    doi = "10.31390/gradschool\_disstheses.5926"
}