Geobiology

Evolution of the protists is discussed on the basis of their known fossil record and the morphological, biochemical, metabolic, physiological, and distributional data concerning modern representatives. Periods of explosive evolution result from the chance appearance of a major innovation and are followed by extensive exploitation of the possibilities of each innovation. A billion years or more following the origination of life were characterized by a biochemical and metabolic stage of differentiation, procaryote structure, rapid biotic turnover, and simple carbon cycle. This was succeeded by a period of intercellular and physiologic differentiation, about 1.5 b.y. in duration, with continued rapid carbon cycling, eucaryotic protist asexual clonal reproduction, and evolution based on mutation-induced variations. The last 0.6 b.y. have been characterized by intercellular differentiation (metaphytes and metazoans), with increased size of the individual, dominance of the diploid phase, and hence increased relative importance of genetic recombination in evolution, with smaller populations, and development of an extremely complex carbon cycle that is more susceptible to periodic disruption. Evolutionary rates in protists are comparable to those of multicellular organisms, although attainment of variability, isolation mechanisms, and selection processes differ. The apparent exponential increase of phytoplankton taxa at successive periods in their geologic history is related to their mutation-based evolution. A hypothetical phylogenetic tree is plotted against the geologic time scale, showing the known extent of the protist fossil record and that of other major groups of organisms, grades of structural and metabolic differentiation, relative age of important Precambrian fossil occurrences, and probable time of appearance of an aerobic environment. The Phanerozoic fossil record of phytoplankton shows periods of maximum productivity interspersed with times of greatly reduced microfloras. Modern distributions and productivity, together with experimental culture data, are related to the geologic past to indicate both possible causes and effects of these fluctuations, in elaboration of a previously proposed Phytoplankton Periodicity Model. The photosynthetic activity of phytoplankton, by which CO 2and H 2O are utilized to produce organic compounds and free oxygen, forms the basis of the oceanic carbon and oxygen cycles and thereby influences atmospheric composition. The areal extent of the oceans and the abundance and rapid growth of the phytoplankton confer prime status on oceanic production in the present-day oxygen balance. Quantitatively, oceanic production was even more important in the geologic past. Oxygen-producing algae appeared some 3 b.y. ago, and a highly oxygenic atmosphere probably was attained geologically soon. Through the interrelated processes of carbon fixation and oxygen production, periods of high oceanic phytoplankton productivity had a somewhat more oxygenic atmosphere, reduced CO 2pressure, and higher oceanic pH. These conditions are recorded by abundant dispersed organic carbon in sediments and petroleum accumulation (both of isotopically light carbon), lime deposition with increasingly heavy carbon isotope ratio, and an abundance of marine filter-feeding, detrital feeding, and carnivorous animal life. Atmospheric conditions were favorable for land animals. Times of greatly limited phytoplankton production resulted in relative oceanic increase of procaryotes, particularly bacteria, increased CO 2levels, lowered pH, and oxygen depletion, silica deposition, less organic carbon in sediments, limestones of increasingly light 12C/ 13C ratio and eventual lime solution, and deposition of gypsum, barite, and other sulfates of isotopically light sulfur. The marine food web was drastically tightened, filter feeders and reef-forming invertebrates were largely eliminated, and only the more efficient food gatherers survived. Relative atmospheric depletion of oxygen affected both marine and terrestrial animals, eliminating many, whereas the increased CO 2pressure stimulated terrestrial plants. The world-wide contemporaneity of certain geochemical, sedimentological, and marine and terrestrial biologic events is suggested by data obtained in numerous unrelated studies. Changes in phytoplankton quantitative distribution, discussed herein, also coincide with these events and are suggested to have formed the connecting link between them.

@incollection{tappan1970geobiologic,
    author = "Tappan, Helen and Loeblich, Alfred R.",
    title = "Geobiologic Implications of Fossil Phytoplankton Evolution and Time-Space Distribution",
    year = "1970",
    booktitle = "Symposium on Palynology of the Late Cretaceous and Early Tertiary",
    abstract = "Evolution of the protists is discussed on the basis of their known fossil record and the morphological, biochemical, metabolic, physiological, and distributional data concerning modern representatives. Periods of explosive evolution result from the chance appearance of a major innovation and are followed by extensive exploitation of the possibilities of each innovation. A billion years or more following the origination of life were characterized by a biochemical and metabolic stage of differentiation, procaryote structure, rapid biotic turnover, and simple carbon cycle. This was succeeded by a period of intercellular and physiologic differentiation, about 1.5 b.y. in duration, with continued rapid carbon cycling, eucaryotic protist asexual clonal reproduction, and evolution based on mutation-induced variations. The last 0.6 b.y. have been characterized by intercellular differentiation (metaphytes and metazoans), with increased size of the individual, dominance of the diploid phase, and hence increased relative importance of genetic recombination in evolution, with smaller populations, and development of an extremely complex carbon cycle that is more susceptible to periodic disruption. Evolutionary rates in protists are comparable to those of multicellular organisms, although attainment of variability, isolation mechanisms, and selection processes differ. The apparent exponential increase of phytoplankton taxa at successive periods in their geologic history is related to their mutation-based evolution. A hypothetical phylogenetic tree is plotted against the geologic time scale, showing the known extent of the protist fossil record and that of other major groups of organisms, grades of structural and metabolic differentiation, relative age of important Precambrian fossil occurrences, and probable time of appearance of an aerobic environment. The Phanerozoic fossil record of phytoplankton shows periods of maximum productivity interspersed with times of greatly reduced microfloras. Modern distributions and productivity, together with experimental culture data, are related to the geologic past to indicate both possible causes and effects of these fluctuations, in elaboration of a previously proposed Phytoplankton Periodicity Model. The photosynthetic activity of phytoplankton, by which CO 2and H 2O are utilized to produce organic compounds and free oxygen, forms the basis of the oceanic carbon and oxygen cycles and thereby influences atmospheric composition. The areal extent of the oceans and the abundance and rapid growth of the phytoplankton confer prime status on oceanic production in the present-day oxygen balance. Quantitatively, oceanic production was even more important in the geologic past. Oxygen-producing algae appeared some 3 b.y. ago, and a highly oxygenic atmosphere probably was attained geologically soon. Through the interrelated processes of carbon fixation and oxygen production, periods of high oceanic phytoplankton productivity had a somewhat more oxygenic atmosphere, reduced CO 2pressure, and higher oceanic pH. These conditions are recorded by abundant dispersed organic carbon in sediments and petroleum accumulation (both of isotopically light carbon), lime deposition with increasingly heavy carbon isotope ratio, and an abundance of marine filter-feeding, detrital feeding, and carnivorous animal life. Atmospheric conditions were favorable for land animals. Times of greatly limited phytoplankton production resulted in relative oceanic increase of procaryotes, particularly bacteria, increased CO 2levels, lowered pH, and oxygen depletion, silica deposition, less organic carbon in sediments, limestones of increasingly light 12C/ 13C ratio and eventual lime solution, and deposition of gypsum, barite, and other sulfates of isotopically light sulfur. The marine food web was drastically tightened, filter feeders and reef-forming invertebrates were largely eliminated, and only the more efficient food gatherers survived. Relative atmospheric depletion of oxygen affected both marine and terrestrial animals, eliminating many, whereas the increased CO 2pressure stimulated terrestrial plants. The world-wide contemporaneity of certain geochemical, sedimentological, and marine and terrestrial biologic events is suggested by data obtained in numerous unrelated studies. Changes in phytoplankton quantitative distribution, discussed herein, also coincide with these events and are suggested to have formed the connecting link between them.",
    url = "https://doi.org/10.1130/spe127-p247",
    doi = "10.1130/spe127-p247",
    openalex = "W2403377992",
    pages = "247-340"
}

@misc{tappen1970geobiological1,
    author = "Tappen, H. and Loeblich, A. R. and Jr",
    title = "Geobiological implications of fossil phytoplankton evolution and time-space distribution",
    year = "1970",
    howpublished = "Geological Society of America, Special Paper, v. 127, p. 247-340",
    note = "talkorigins\_source = {true}; raw\_reference = {Tappen, H., and Loeblich, A. R., Jr., 1970, Geobiological implications of fossil phytoplankton evolution and time-space distribution: Geological Society of America, Special Paper, v. 127, p. 247-340.}"
}

Data on numbers of marine families within 91 metazoan classes known from the Phanerozoic fossil record are analyzed. The distribution of the 2800 fossil families among the classes is very uneven, with most belonging to a small minority of classes. Similarly, the stratigraphic distribution of the classes is very uneven, with most first appearing early in the Paleozoic and with many of the smaller classes becoming extinct before the end of that era. However, despite this unevenness, a Q -mode factor analysis indicates that the structure of these data is rather simple. Only three factors are needed to account for more than 90% of the data. These factors are interpreted as reflecting the three great “evolutionary faunas” of the Phanerozoic marine record: a trilobite-dominated Cambrian fauna, a brachiopod-dominated later Paleozoic fauna, and a mollusc-dominated Mesozoic-Cenozoic, or “modern,” fauna. Lesser factors relate to slow taxonomic turnover within the major faunas through time and to unique aspects of particular taxa and times. Each of the three major faunas seems to have its own characteristic diversity so that its expansion or contraction appears as being intimately associated with a particular phase in the history of total marine diversity. The Cambrian fauna expands rapidly during the Early Cambrian radiations and maintains dominance during the Middle to Late Cambrian “equilibrium.” The Paleozoic fauna then ascends to dominance during the Ordovician radiations, which increase diversity dramatically; this new fauna then maintains dominance throughout the long interval of apparent equilibrium that lasts until the end of the Paleozoic Era. The modern fauna, which slowly increases in importance during the Paleozoic Era, quickly rises to dominance with the Late Permian extinctions and maintains that status during the general rise in diversity to the apparent maximum in the Neogene. The increase in diversity associated with the expansion of each new fauna appears to coincide with an approximately exponential decline of the previously dominant fauna, suggesting possible displacement of each evolutionary fauna by its successor.

@article{doi101017s0094837300003778,
    author = "Sepkoski, J. John",
    title = "A factor analytic description of the Phanerozoic marine fossil record",
    year = "1981",
    journal = "Paleobiology",
    abstract = "Data on numbers of marine families within 91 metazoan classes known from the Phanerozoic fossil record are analyzed. The distribution of the 2800 fossil families among the classes is very uneven, with most belonging to a small minority of classes. Similarly, the stratigraphic distribution of the classes is very uneven, with most first appearing early in the Paleozoic and with many of the smaller classes becoming extinct before the end of that era. However, despite this unevenness, a Q -mode factor analysis indicates that the structure of these data is rather simple. Only three factors are needed to account for more than 90\% of the data. These factors are interpreted as reflecting the three great “evolutionary faunas” of the Phanerozoic marine record: a trilobite-dominated Cambrian fauna, a brachiopod-dominated later Paleozoic fauna, and a mollusc-dominated Mesozoic-Cenozoic, or “modern,” fauna. Lesser factors relate to slow taxonomic turnover within the major faunas through time and to unique aspects of particular taxa and times. Each of the three major faunas seems to have its own characteristic diversity so that its expansion or contraction appears as being intimately associated with a particular phase in the history of total marine diversity. The Cambrian fauna expands rapidly during the Early Cambrian radiations and maintains dominance during the Middle to Late Cambrian “equilibrium.” The Paleozoic fauna then ascends to dominance during the Ordovician radiations, which increase diversity dramatically; this new fauna then maintains dominance throughout the long interval of apparent equilibrium that lasts until the end of the Paleozoic Era. The modern fauna, which slowly increases in importance during the Paleozoic Era, quickly rises to dominance with the Late Permian extinctions and maintains that status during the general rise in diversity to the apparent maximum in the Neogene. The increase in diversity associated with the expansion of each new fauna appears to coincide with an approximately exponential decline of the previously dominant fauna, suggesting possible displacement of each evolutionary fauna by its successor.",
    url = "https://doi.org/10.1017/s0094837300003778",
    doi = "10.1017/s0094837300003778",
    openalex = "W2505144080",
    references = "doi10100797814613088367, doi1010160012825272900724, doi101017s0094837300004917, doi101017s009483730000508x, doi101017s0094837300005236, doi101017s0094837300005352, doi101017s0094837300005649, doi101017s0094837300005972, doi101017s0094837300012549, doi101126science17740541065, doi101126science2064415217, doi101130spe89p63, doi1023071483846, doi1023071796560, doi1023072405671, doi1023072412725, doi1023072412728, doi1023072806339, doi107312simp93764, openalexw1504049102, openalexw645218623"
}

A new compilation of fossil data on invertebrate and vertebrate families indicates that four mass extinctions in the marine realm are statistically distinct from background extinction levels. These four occurred late in the Ordovician, Permian, Triassic, and Cretaceous periods. A fifth extinction event in the Devonian stands out from the background but is not statistically significant in these data. Background extinction rates appear to have declined since Cambrian time, which is consistent with the prediction that optimization of fitness should increase through evolutionary time.

@article{doi101126science21545391501,
    author = "Raup, David M. and Sepkoski, J. John",
    title = "Mass Extinctions in the Marine Fossil Record",
    year = "1982",
    journal = "Science",
    abstract = "A new compilation of fossil data on invertebrate and vertebrate families indicates that four mass extinctions in the marine realm are statistically distinct from background extinction levels. These four occurred late in the Ordovician, Permian, Triassic, and Cretaceous periods. A fifth extinction event in the Devonian stands out from the background but is not statistically significant in these data. Background extinction rates appear to have declined since Cambrian time, which is consistent with the prediction that optimization of fitness should increase through evolutionary time.",
    url = "https://doi.org/10.1126/science.215.4539.1501",
    doi = "10.1126/science.215.4539.1501",
    openalex = "W1976721572",
    references = "doi101017s009483730000511x, doi101017s0094837300006539, doi101130spe89p63, doi105281zenodo16226412, openalexw2335729143, openalexw2591197405, openalexw2596207362"
}

Catastrophic hypotheses for mass extinctions are commonly criticized because many taxa gradually disappear from the fossil record prior to the extinction. Presumably, a geologically instantaneous catastrophe would not cause a reduction in diversity or a series of minor extinctions before the actual mass extinction. Two types of sampling effects, however, could cause taxa to appear to decline before their actual biotic extinction. The first of these is reduced sample size provided in the sedimentary record and the second, which we examine in greater detail, is artificial range truncation. The fossil record is discontinuous in time and the recorded ranges of species or of higher taxa can only extend to their last known occurrence in the fossil record. If the distribution of last occurrences is random with respect to actual biotic extinction, then apparent extinctions will begin well before a mass extinction and will gradually increase in frequency until the mass extinction event, thus giving the appearance of a gradual extinction. Other factors, such as regressions, can exacerbate the bias toward gradual disappearance of taxa from the fossil record. Hence, gradual extinction patterns prior to a mass extinction do not necessarily eliminate catastrophic extinction hypotheses. The recorded ranges of fossils, especially of uncommon taxa or taxa in habitats not represented by a continuous record, may be inadequate to test either gradual or catastrophic hypotheses.

@incollection{doi101130spe190p291,
    author = "Signor, Philip W. and Lipps, Jere H.",
    title = "Sampling bias, gradual extinction patterns and catastrophes in the fossil record",
    year = "1982",
    booktitle = "Geological Society of America eBooks",
    abstract = "Catastrophic hypotheses for mass extinctions are commonly criticized because many taxa gradually disappear from the fossil record prior to the extinction. Presumably, a geologically instantaneous catastrophe would not cause a reduction in diversity or a series of minor extinctions before the actual mass extinction. Two types of sampling effects, however, could cause taxa to appear to decline before their actual biotic extinction. The first of these is reduced sample size provided in the sedimentary record and the second, which we examine in greater detail, is artificial range truncation. The fossil record is discontinuous in time and the recorded ranges of species or of higher taxa can only extend to their last known occurrence in the fossil record. If the distribution of last occurrences is random with respect to actual biotic extinction, then apparent extinctions will begin well before a mass extinction and will gradually increase in frequency until the mass extinction event, thus giving the appearance of a gradual extinction. Other factors, such as regressions, can exacerbate the bias toward gradual disappearance of taxa from the fossil record. Hence, gradual extinction patterns prior to a mass extinction do not necessarily eliminate catastrophic extinction hypotheses. The recorded ranges of fossils, especially of uncommon taxa or taxa in habitats not represented by a continuous record, may be inadequate to test either gradual or catastrophic hypotheses.",
    url = "https://doi.org/10.1130/spe190-p291",
    doi = "10.1130/spe190-p291",
    openalex = "W2414724882"
}

Summary 1. Modes of larval development play important roles in the ecology, biogeography, and evolution of marine benthic organisms. Studies of the larval ecology of fossil organisms can contribute greatly to our understanding of such roles by allowing us to race effects on evolutionary time scales. 2. Modes of development can be inferred for well preserved molluscan fossils because the size of the initial larval shell (Protoconch I in gastropods, Prodissoconch I in bivalves) reflects egg size. Other morphological criteria are also available, and a comparative approach based on related taxa with known development may be the most reliable method. By combining larval and adult traits, it is possible to recognize modes of larval development in at least some fossil bryozoans, brachiopods, and echinoderms as well. (a) Planktotrophic larvae arise from small eggs, are released in enormous numbers with little parental investment per offspring, and suffer tremendous mortality during and shortly after a planktic existence. These larvae feed on the plankton during development, and are commonly capable of a prolonged free‐swimming existence, and thus wide dispersal. (b) Nonplanktotrophic larvae (which include both planktic lecithotrophic forms and ‘direct developers’) generally arise from large eggs, with relatively few young produced per parent. Relative to planktotrophic larvae, nonplanktotrophic larvae generally receive greater parental investment per larva, and larval mortality is generally lower. These larvae rely on yolk for nutrition during development, and planktic durations are generally much briefer than for species with planktotrophic larvae, so that dispersal capability is considerably less. Energetic investment per egg is generally higher than in planktotrophs, but as there are lower fecundities as well it is difficult to generalize about the total energetic cost of one mode of reproduction against the other. 3. Owing to the high dispersal capability of planktotrophic larvae, it has been suggested that species with such larvae will be geographically widespread, geologically long‐ranging, and exhibit low speciation and extinction rates. Species with nonplanktotrophic larvae will tend to be geographically more restricted, geologically short‐ranging, and exhibit high speciation and extinction rates (again, as a consequence of their characteristically low larval dispersal capabilities). 4. Recognition of differential dispersal capabilities can play a role in paleobiogeo‐graphic analyses. Concurrent study of the distribution of groups with contrasting modes of development will permit testing of hypotheses concerning timing, magnitudes and frequencies of migration and vicariance events. 5. Larval types are not randomly distributed in the oceans, but relationships with other aspects of the organisms' biology and habitats are very complex. Mode of development varies with: (a) Ecology. A simple r–––K model of adaptive strategies is clearly insufficient to explain the observed relationships: while many ‘equilibrium’ species have nonplanktotrophic larvae, and organisms living in less prdictable environments often have planktotrophic larvae, some of the most opportunistic marine species have nonplanktotrophic larvae. Nonetheless, planktotrophic development seems most suited for exploitation of patchy but widespread habitats. (b) Latitude. At shelf depths, planktotrophy is predominant in the tropics, and decreases sharply at high latitudes. (c) Depth. Incidence of planktotrophy decreases with depth across the continental shelf, at least in some taxa. Beyond the shelf, many deep‐sea organisms are nonplanktotrophic (e.g. most bivalves, peracarid crustaceans), but planktotrophic development appears to be present in other groups (prosobranch gastropods, ophiuroids, and bivalves inhabiting transient habitats such as sunken wood and hydrothermal vents). These trends in developmental types will be accompanied by trends in evolutionary rates and patterns as outlined above. The study of larval ecology by paleobiologists will yield insights into the processes that gave rise to ancient evolutionary and biogeographic patterns, and will permit the development and testing of hypotheses on the origins of the patterns observed in modern seas.

@article{doi101111j1469185x1983tb00380x,
    author = "Jablonski, David and Lutz, Richard A.",
    title = "LARVAL ECOLOGY OF MARINE BENTHIC INVERTEBRATES: PALEOBIOLOGICAL IMPLICATIONS",
    year = "1983",
    journal = "Biological reviews/Biological reviews of the Cambridge Philosophical Society",
    abstract = "Summary 1. Modes of larval development play important roles in the ecology, biogeography, and evolution of marine benthic organisms. Studies of the larval ecology of fossil organisms can contribute greatly to our understanding of such roles by allowing us to race effects on evolutionary time scales. 2. Modes of development can be inferred for well preserved molluscan fossils because the size of the initial larval shell (Protoconch I in gastropods, Prodissoconch I in bivalves) reflects egg size. Other morphological criteria are also available, and a comparative approach based on related taxa with known development may be the most reliable method. By combining larval and adult traits, it is possible to recognize modes of larval development in at least some fossil bryozoans, brachiopods, and echinoderms as well. (a) Planktotrophic larvae arise from small eggs, are released in enormous numbers with little parental investment per offspring, and suffer tremendous mortality during and shortly after a planktic existence. These larvae feed on the plankton during development, and are commonly capable of a prolonged free‐swimming existence, and thus wide dispersal. (b) Nonplanktotrophic larvae (which include both planktic lecithotrophic forms and ‘direct developers’) generally arise from large eggs, with relatively few young produced per parent. Relative to planktotrophic larvae, nonplanktotrophic larvae generally receive greater parental investment per larva, and larval mortality is generally lower. These larvae rely on yolk for nutrition during development, and planktic durations are generally much briefer than for species with planktotrophic larvae, so that dispersal capability is considerably less. Energetic investment per egg is generally higher than in planktotrophs, but as there are lower fecundities as well it is difficult to generalize about the total energetic cost of one mode of reproduction against the other. 3. Owing to the high dispersal capability of planktotrophic larvae, it has been suggested that species with such larvae will be geographically widespread, geologically long‐ranging, and exhibit low speciation and extinction rates. Species with nonplanktotrophic larvae will tend to be geographically more restricted, geologically short‐ranging, and exhibit high speciation and extinction rates (again, as a consequence of their characteristically low larval dispersal capabilities). 4. Recognition of differential dispersal capabilities can play a role in paleobiogeo‐graphic analyses. Concurrent study of the distribution of groups with contrasting modes of development will permit testing of hypotheses concerning timing, magnitudes and frequencies of migration and vicariance events. 5. Larval types are not randomly distributed in the oceans, but relationships with other aspects of the organisms' biology and habitats are very complex. Mode of development varies with: (a) Ecology. A simple r–––K model of adaptive strategies is clearly insufficient to explain the observed relationships: while many ‘equilibrium’ species have nonplanktotrophic larvae, and organisms living in less prdictable environments often have planktotrophic larvae, some of the most opportunistic marine species have nonplanktotrophic larvae. Nonetheless, planktotrophic development seems most suited for exploitation of patchy but widespread habitats. (b) Latitude. At shelf depths, planktotrophy is predominant in the tropics, and decreases sharply at high latitudes. (c) Depth. Incidence of planktotrophy decreases with depth across the continental shelf, at least in some taxa. Beyond the shelf, many deep‐sea organisms are nonplanktotrophic (e.g. most bivalves, peracarid crustaceans), but planktotrophic development appears to be present in other groups (prosobranch gastropods, ophiuroids, and bivalves inhabiting transient habitats such as sunken wood and hydrothermal vents). These trends in developmental types will be accompanied by trends in evolutionary rates and patterns as outlined above. The study of larval ecology by paleobiologists will yield insights into the processes that gave rise to ancient evolutionary and biogeographic patterns, and will permit the development and testing of hypotheses on the origins of the patterns observed in modern seas.",
    url = "https://doi.org/10.1111/j.1469-185x.1983.tb00380.x",
    doi = "10.1111/j.1469-185x.1983.tb00380.x",
    openalex = "W2060347297",
    references = "doi1010160016003258902862, doi1010160302352475900389, doi101016b9780122825057500129, doi101016b9780122825057x50015, doi101017s0094837300003778, doi101017s0094837300005224, doi101017s0094837300005236, doi101017s0094837300005649, doi101017s0094837300005662, doi101017s0094837300016894, doi101086282697, doi101086409052, doi101093icb153717, doi101111j150239311977tb00628x, doi101111j155856461978tb04642x, doi101126science150369228, doi101126science18040931377, doi1015159781400881376, doi101525aa195052402a00270, doi1023071292581, doi1023071483846, doi1023072407204, doi1025773v5jaxgtq24, doi104159harvard9780674865327, hartnoll1975chemoreception, howells1950genetics, openalexw1549886310, openalexw2506868775, openalexw2531009674, openalexw3135630760, openalexw3208881761, openalexw565715315, stanley1978chronospecies"
}

Chapter 1 has outlined the extent to which many endemic Mascarene Island birds have become extinct, probably during the last 300 years since man arrived on the islands. Thirty extinct species are recognised today (Cowles in press), but of these only five are known from skins preserved in museums and institutions throughout the world. Four of these species, the Mauritian Blue Pigeon Alectroenas nitidissima, the Mascarene Parrot from Réunion Mascarinus mascarinus, the Rodrigues Parakeet Psittacula exsul and the contentious Leguat's Starling Necropsar (Orphanopsar) leguati of unknown locality, are represented by a total of only eight skins. The Reunion Crested Starling Fregilupus varius was better represented by 24-25 skins, all documented by Hachisuka (1953), although fewer survive today (Chapter 1). The remaining 25 extinct species are known only from fossil bones discovered in caverns and deposits on the three islands. In number these range to well over 200 elements for the better known Solitaire of Rodrigues Pezophaps solitaria and perhaps the Mauritius Dodo Raphus cucullatus, but the remaining species are unfortunately known from very few bones or bone fragments.

@incollection{doi101017cbo9780511735769004,
    author = "Cowles, G. S.",
    title = "The fossil record",
    year = "1987",
    booktitle = "Cambridge University Press eBooks",
    abstract = "Chapter 1 has outlined the extent to which many endemic Mascarene Island birds have become extinct, probably during the last 300 years since man arrived on the islands. Thirty extinct species are recognised today (Cowles in press), but of these only five are known from skins preserved in museums and institutions throughout the world. Four of these species, the Mauritian Blue Pigeon Alectroenas nitidissima, the Mascarene Parrot from Réunion Mascarinus mascarinus, the Rodrigues Parakeet Psittacula exsul and the contentious Leguat's Starling Necropsar (Orphanopsar) leguati of unknown locality, are represented by a total of only eight skins. The Reunion Crested Starling Fregilupus varius was better represented by 24-25 skins, all documented by Hachisuka (1953), although fewer survive today (Chapter 1). The remaining 25 extinct species are known only from fossil bones discovered in caverns and deposits on the three islands. In number these range to well over 200 elements for the better known Solitaire of Rodrigues Pezophaps solitaria and perhaps the Mauritius Dodo Raphus cucullatus, but the remaining species are unfortunately known from very few bones or bone fragments.",
    url = "https://doi.org/10.1017/cbo9780511735769.004",
    doi = "10.1017/cbo9780511735769.004",
    openalex = "W2496925084"
}

Insects possess a surprisingly extensive fossil record. Compilation of the geochronologic ranges of insect families demonstrates that their diversity exceeds that of preserved vertebrate tetrapods through 91 percent of their evolutionary history. The great diversity of insects was achieved not by high origination rates but rather by low extinction rates comparable to the low rates of slowly evolving marine invertebrate groups. The great radiation of modern insects began 245 million years ago and was not accelerated by the expansion of angiosperms during the Cretaceous period. The basic trophic machinery of insects was in place nearly 100 million years before angiosperms appeared in the fossil record.

@article{doi101126science11536548,
    author = "Labandeira, Conrad C. and Sepkoski, J. John",
    title = "Insect Diversity in the Fossil Record",
    year = "1993",
    journal = "Science",
    abstract = "Insects possess a surprisingly extensive fossil record. Compilation of the geochronologic ranges of insect families demonstrates that their diversity exceeds that of preserved vertebrate tetrapods through 91 percent of their evolutionary history. The great diversity of insects was achieved not by high origination rates but rather by low extinction rates comparable to the low rates of slowly evolving marine invertebrate groups. The great radiation of modern insects began 245 million years ago and was not accelerated by the expansion of angiosperms during the Cretaceous period. The basic trophic machinery of insects was in place nearly 100 million years before angiosperms appeared in the fossil record.",
    url = "https://doi.org/10.1126/science.11536548",
    doi = "10.1126/science.11536548",
    openalex = "W1984084181",
    references = "doi1010079781468491814, doi101017s0094837300003778, doi101038293435a0, doi101038303614a0, doi101086284840, doi101111j155856461964tb01674x, doi101111j155856461966tb03364x, doi101126science13334591105, doi101126science21545391501, doi101126science2314734129, doi101146annureves10110179001335, doi107312simp93764, openalexw2038423019"
}

@article{doi10103841710,
    author = "Shubin, Neil and Tabin, Cliff and Carroll, Sean B.",
    title = "Fossils, genes and the evolution of animal limbs",
    year = "1997",
    journal = "Nature",
    url = "https://doi.org/10.1038/41710",
    doi = "10.1038/41710",
    openalex = "W1601043516",
    references = "doi101002jez1401080304, doi1010160092867493906262, doi1010160092867493906273, doi1010160092867493906284, doi101016s0092867400811149, doi101017s0263593300006787, doi101038368208a0, doi101038376479a0, doi10108011035899509546213, doi101093aesa283408, doi101111j109636421995tb00110x, doi101111j109636421995tb00119x, doi101111j150239311996tb01839x, doi101126science2504981658, doi10182618200376605199601, doi1023072992562, doi1023073223017, doi105281zenodo16171435, doi107208chicago97802262565730010001"
}

The Mickwitzia sandstone, south-central Sweden, consists of about 10 m of Lower Cambrian clastic sediments deposited in an epicontinental setting. An in formal, lithologically based subdivision, A-E, is introduced. A thin basal conglomerate (interval A) is followed by thin-bedded sand and siltstone with c1ayey partings (interval B and D) and medium-grained sandstone (interval C), largely representing subtidal storm deposits. Interval E consists of thick-bedded shoreface deposits. Heterolithic intervals have well-preserved trace fossils, including Cruziana, Rusophycus, Gyrolithes, Treptichnus and Teichichnus. Beds with impure, often weakly cemented sandstone (interval C) have Rhizocorallium, Monocraterion and Skolithos. Trace fossils are dominated by infaunal feeding and feeding?-dwelling burrows; 40 ichnotaxa are recognized, representing the activity of but a few types of animals. The type material of Monocraterion tentaculatum Torell, 1870, is illustrated for the first time, and the relationship of Monocraterion to Skolithos and Rosselia is discussed. Previously poorly known taxa are described. Scotolithus mirabilis Linnarsson, 1871, consists of a vertical shaft which in its lower part diverges into a wide broom-shaped arrangement. Spiroscolex spiralis (Torell, 1870) is a little-used name for burrows identical to Gyrolithes polonicus. Halopoa imbricata Torell, 1870, is a burrow related to Palaeophycus sulcatus, with a morphology dependant on sediment consistency: it is here assigned to Palaeophycus imbricatus. Fraena tenella Linnarsson, 1871, is assigned to Cruziana and considered a subjective senior synonym of Cruziana problematica. Phycodes pedum Seilacher, 1955, should be assigned to Treptichnus.

@incollection{doi10182618200376656199701,
    author = "Jensen, Sören",
    title = "Trace fossils from the Lower Cambrian Mickwitzia sandstone, south-central Sweden",
    year = "1997",
    booktitle = "Fossils and strata",
    abstract = "The Mickwitzia sandstone, south-central Sweden, consists of about 10 m of Lower Cambrian clastic sediments deposited in an epicontinental setting. An in formal, lithologically based subdivision, A-E, is introduced. A thin basal conglomerate (interval A) is followed by thin-bedded sand and siltstone with c1ayey partings (interval B and D) and medium-grained sandstone (interval C), largely representing subtidal storm deposits. Interval E consists of thick-bedded shoreface deposits. Heterolithic intervals have well-preserved trace fossils, including Cruziana, Rusophycus, Gyrolithes, Treptichnus and Teichichnus. Beds with impure, often weakly cemented sandstone (interval C) have Rhizocorallium, Monocraterion and Skolithos. Trace fossils are dominated by infaunal feeding and feeding?-dwelling burrows; 40 ichnotaxa are recognized, representing the activity of but a few types of animals. The type material of Monocraterion tentaculatum Torell, 1870, is illustrated for the first time, and the relationship of Monocraterion to Skolithos and Rosselia is discussed. Previously poorly known taxa are described. Scotolithus mirabilis Linnarsson, 1871, consists of a vertical shaft which in its lower part diverges into a wide broom-shaped arrangement. Spiroscolex spiralis (Torell, 1870) is a little-used name for burrows identical to Gyrolithes polonicus. Halopoa imbricata Torell, 1870, is a burrow related to Palaeophycus sulcatus, with a morphology dependant on sediment consistency: it is here assigned to Palaeophycus imbricatus. Fraena tenella Linnarsson, 1871, is assigned to Cruziana and considered a subjective senior synonym of Cruziana problematica. Phycodes pedum Seilacher, 1955, should be assigned to Treptichnus.",
    url = "https://doi.org/10.18261/8200376656-1997-01",
    doi = "10.18261/8200376656-1997-01",
    openalex = "W4385643405",
    references = "bridge1985unusual, doi10100797814757131762, doi1010160012825283900223, doi1010160025322767900515, doi1010160031018279901123, doi1010160037073884900034, doi1010160191814182900463, doi10108003115518908527821, doi101111j136530911977tb00134x, doi101111j150239311969tb01258x, doi101111j150239311980tb00632x, doi101126science22246281123, doi10113000167606198293663hssoiv20co2, doi101139e87124, doi101306212f7e4b2b2411d78648000102c1865d, doi101306212f89c22b2411d78648000102c1865d, doi10182618200049639197506, doi10182618200093301197301, doi10182618200374254198901, doi10182618200374742199101, doi1023073514911, doi105281zenodo15992748, doi105860choice304422, openalexw2344228935, openalexw2603635224, openalexw3116078484, openalexw3126336940, openalexw353142951, openalexw574363047, roberts1982facies"
}

Molecular fossils of biological lipids are preserved in 2700-million-year-old shales from the Pilbara Craton, Australia. Sequential extraction of adjacent samples shows that these hydrocarbon biomarkers are indigenous and syngenetic to the Archean shales, greatly extending the known geological range of such molecules. The presence of abundant 2α-methylhopanes, which are characteristic of cyanobacteria, indicates that oxygenic photosynthesis evolved well before the atmosphere became oxidizing. The presence of steranes, particularly cholestane and its 28- to 30-carbon analogs, provides persuasive evidence for the existence of eukaryotes 500 million to 1 billion years before the extant fossil record indicates that the lineage arose.

@article{doi101126science28554301033,
    author = "Brocks, Jochen J. and Logan, Graham A. and Buick, Roger and Summons, Roger E.",
    title = "Archean Molecular Fossils and the Early Rise of Eukaryotes",
    year = "1999",
    journal = "Science",
    abstract = "Molecular fossils of biological lipids are preserved in 2700-million-year-old shales from the Pilbara Craton, Australia. Sequential extraction of adjacent samples shows that these hydrocarbon biomarkers are indigenous and syngenetic to the Archean shales, greatly extending the known geological range of such molecules. The presence of abundant 2α-methylhopanes, which are characteristic of cyanobacteria, indicates that oxygenic photosynthesis evolved well before the atmosphere became oxidizing. The presence of steranes, particularly cholestane and its 28- to 30-carbon analogs, provides persuasive evidence for the existence of eukaryotes 500 million to 1 billion years before the extant fossil record indicates that the lineage arose.",
    url = "https://doi.org/10.1126/science.285.5430.1033",
    doi = "10.1126/science.285.5430.1033",
    openalex = "W2032247127",
    references = "doi101038362834a0, doi101038376053a0, doi101038384055a0, doi101126science11539686, doi101126science1585174, doi101126science1603829729, doi101126science1631544, doi101126science2605108640, doi101146annurevmi41100187001505, doi102113gsecongeo6871135"
}

@article{doi101016s0031018201002085,
    author = "Steiner, Michael and Wallis, Eckart and Erdtmann, Bernd-Dietrich and Zhao, Yuanlong and Yang, Ruidong",
    title = "Submarine-hydrothermal exhalative ore layers in black shales from South China and associated fossils — insights into a Lower Cambrian facies and bio-evolution",
    year = "2001",
    journal = "Palaeogeography Palaeoclimatology Palaeoecology",
    url = "https://doi.org/10.1016/s0031-0182(01)00208-5",
    doi = "10.1016/s0031-0182(01)00208-5",
    openalex = "W2115053158",
    references = "doi1010160009254180900479, doi1010160009254186900781, doi1010160012821x84900396, doi101016003101829390065q, doi1010160031920186900932, doi101016003192018990263x, doi101017cbo9780511601064, doi101038267403a0, doi101126science2464928339, doi101126science2705236598, doi1011300091761319940220179pcbgsr23co2, doi101144gsjgs14920171, doi101306m20377, doi10182618200374742199101, doi1023072992562, openalexw1624806571"
}

▪ Abstract Fossil deposits that preserve soft-bodied organisms provide critical evidence of the history of life. Usually, only more decay resistant materials, e.g., cuticles, survive as organic remains as a result of selective preservation and subsequent diagenesis to more resistant biopolymers. Permineralization, the permeation of tissues by mineralizing fluids, may preserve remarkable detail, particularly of plants. However, evidence of more labile tissues, e.g., muscle, normally requires the replication of their morphology by rapid in situ growth of minerals, i.e., authigenic mineralization. This process relies on the steep geochemical gradients generated by decay microbes. The minerals involved, and the level of detail preserved (which may be subcellular), depend on a number of factors, including the nature of microbial activity and amount of decay, availability of ions, and the type of organism that is fossilized. Understanding these controls is essential to determining the conditions that favor exceptional preservation.

@article{briggs2003the,
    author = "Briggs, Derek E.G.",
    title = "The Role of Decay and Mineralization in the Preservation of Soft-Bodied Fossils",
    year = "2003",
    journal = "Annual Review of Earth and Planetary Sciences",
    abstract = "▪ Abstract Fossil deposits that preserve soft-bodied organisms provide critical evidence of the history of life. Usually, only more decay resistant materials, e.g., cuticles, survive as organic remains as a result of selective preservation and subsequent diagenesis to more resistant biopolymers. Permineralization, the permeation of tissues by mineralizing fluids, may preserve remarkable detail, particularly of plants. However, evidence of more labile tissues, e.g., muscle, normally requires the replication of their morphology by rapid in situ growth of minerals, i.e., authigenic mineralization. This process relies on the steep geochemical gradients generated by decay microbes. The minerals involved, and the level of detail preserved (which may be subcellular), depend on a number of factors, including the nature of microbial activity and amount of decay, availability of ions, and the type of organism that is fossilized. Understanding these controls is essential to determining the conditions that favor exceptional preservation.",
    url = "https://doi.org/10.1146/annurev.earth.31.100901.144746",
    doi = "10.1146/annurev.earth.31.100901.144746",
    number = "1",
    openalex = "W2125375419",
    pages = "275-301",
    volume = "31",
    references = "allison1988the, briggs1994decay, briggs1996the, doi1010160016703789901919, doi1010160016703794902984, doi101016002532279390147n, doi1010160034666775900056, doi101017s0006323199005472, doi101017s0022336000040026, doi101017s0094837300009994, doi101017s009483730001188x, doi101017s0094837300012082, doi101098rstb19790006, doi101098rstb19850134, doi101098rstb19930082, doi101111j150239311983tb01993x, doi101126science25951001439, doi101126science28153801173, doi1011300091761319880160149mibbbs23co2, doi1015159781501509247, doi1016660094837320020280155lgatio20co2, doi1023071222284, doi1023073515360, doi1023073515363, doi105860choice284524, doi107208chicago97802261597130010001, openalexw2754161204"
}

The use of nucleotide and amino acid sequences allows improved understanding of the timing of evolutionary events of life on earth. Molecular estimates of divergence times are, however, controversial and are generally much more ancient than suggested by the fossil record. The limited number of genes and species explored and pervasive variations in evolutionary rates are the most likely sources of such discrepancies. Here we compared concatenated amino acid sequences of 129 proteins from 36 eukaryotes to determine the divergence times of several major clades, including animals, fungi, plants, and various protists. Due to significant variations in their evolutionary rates, and to handle the uncertainty of the fossil record, we used a Bayesian relaxed molecular clock simultaneously calibrated by six paleontological constraints. We show that, according to 95% credibility intervals, the eukaryotic kingdoms diversified 950-1,259 million years ago (Mya), animals diverged from choanoflagellates 761-957 Mya, and the debated age of the split between protostomes and deuterostomes occurred 642-761 Mya. The divergence times appeared to be robust with respect to prior assumptions and paleontological calibrations. Interestingly, these relaxed clock time estimates are much more recent than those obtained under the assumption of a global molecular clock, yet bilaterian diversification appears to be approximately 100 million years more ancient than the Cambrian boundary.

@article{doi101073pnas0403984101,
    author = "Douzery, Emmanuel and Snell, Elizabeth A. and Bapteste, Éric and Delsuc, Frédéric and Philippe, Hervé",
    title = "The timing of eukaryotic evolution: Does a relaxed molecular clock reconcile proteins and fossils?",
    year = "2004",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "The use of nucleotide and amino acid sequences allows improved understanding of the timing of evolutionary events of life on earth. Molecular estimates of divergence times are, however, controversial and are generally much more ancient than suggested by the fossil record. The limited number of genes and species explored and pervasive variations in evolutionary rates are the most likely sources of such discrepancies. Here we compared concatenated amino acid sequences of 129 proteins from 36 eukaryotes to determine the divergence times of several major clades, including animals, fungi, plants, and various protists. Due to significant variations in their evolutionary rates, and to handle the uncertainty of the fossil record, we used a Bayesian relaxed molecular clock simultaneously calibrated by six paleontological constraints. We show that, according to 95\% credibility intervals, the eukaryotic kingdoms diversified 950-1,259 million years ago (Mya), animals diverged from choanoflagellates 761-957 Mya, and the debated age of the split between protostomes and deuterostomes occurred 642-761 Mya. The divergence times appeared to be robust with respect to prior assumptions and paleontological calibrations. Interestingly, these relaxed clock time estimates are much more recent than those obtained under the assumption of a global molecular clock, yet bilaterian diversification appears to be approximately 100 million years more ancient than the Cambrian boundary.",
    url = "https://doi.org/10.1073/pnas.0403984101",
    doi = "10.1073/pnas.0403984101",
    openalex = "W2059383371",
    references = "doi101016b9781483227344500176, doi10103835083562, doi10103844766, doi101038nrg1020, doi101093bioinformatics133235, doi101093molbevmsh075, doi101093oxfordjournalsmolbeva025731, doi101093oxfordjournalsmolbeva025892, doi101126science1061457, doi101126science1069651, doi101126science147365368, doi101126science28554301033, doi10182618200376494199401"
}

The community structure and ecological function of contemporary marine ecosystems are critically dependent on eukaryotic phytoplankton. Although numerically inferior to cyanobacteria, these organisms are responsible for the majority of the flux of organic matter to higher trophic levels and the ocean interior. Photosynthetic eukaryotes evolved more than 1.5 billion years ago in the Proterozoic oceans. However, it was not until the Mesozoic Era (251 to 65 million years ago) that the three principal phytoplankton clades that would come to dominate the modern seas rose to ecological prominence. In contrast to their pioneering predecessors, the dinoflagellates, coccolithophores, and diatoms all contain plastids derived from an ancestral red alga by secondary symbiosis. Here we examine the geological, geochemical, and biological processes that contributed to the rise of these three, distantly related, phytoplankton groups.

@article{doi101126science1095964,
    author = "Falkowski, Paul G. and Katz, Miriam and Knoll, Andrew H. and Quigg, Antonietta and Raven, John A. and Schofield, Oscar and Taylor, F. J. R.",
    title = "The Evolution of Modern Eukaryotic Phytoplankton",
    year = "2004",
    journal = "Science",
    abstract = "The community structure and ecological function of contemporary marine ecosystems are critically dependent on eukaryotic phytoplankton. Although numerically inferior to cyanobacteria, these organisms are responsible for the majority of the flux of organic matter to higher trophic levels and the ocean interior. Photosynthetic eukaryotes evolved more than 1.5 billion years ago in the Proterozoic oceans. However, it was not until the Mesozoic Era (251 to 65 million years ago) that the three principal phytoplankton clades that would come to dominate the modern seas rose to ecological prominence. In contrast to their pioneering predecessors, the dinoflagellates, coccolithophores, and diatoms all contain plastids derived from an ancestral red alga by secondary symbiosis. Here we examine the geological, geochemical, and biological processes that contributed to the rise of these three, distantly related, phytoplankton groups.",
    url = "https://doi.org/10.1126/science.1095964",
    doi = "10.1126/science.1095964",
    openalex = "W2136668140",
    references = "doi10103823005, doi101093molbevmsh075, doi101126science1069651, doi101126science27252651155, doi101126science2895480756, doi1011300016760619951071164mlccot23co2, doi1016660094837320000260386bpngns20co2, doi10182618200376494199401"
}

▪ Abstract The evolutionary succession of marine photoautotrophs began with the origin of photosynthesis in the Archean Eon, perhaps as early as 3.8 billion years ago. Since that time, Earth's atmosphere, continents, and oceans have undergone substantial cyclic and secular physical, chemical, and biological changes that selected for different phytoplankton taxa. Early in the history of eukaryotic algae, between 1.6 and 1.2 billion years ago, an evolutionary schism gave rise to “green” (chlorophyll b–containing) and “red” (chlorophyll c–containing) plastid groups. Members of the “green” plastid line were important constituents of Neoproterozoic and Paleozoic oceans, and, ultimately, one green clade colonized land. By the mid-Mesozoic, the green line had become ecologically less important in the oceans. In its place, three groups of chlorophyll c–containing eukaryotes, the dinoflagellates, coccolithophorids, and diatoms, began evolutionary trajectories that have culminated in ecological dominance in the contemporary oceans. Breakup of the supercontinent Pangea, continental shelf flooding, and changes in ocean redox chemistry may all have contributed to this evolutionary transition. At the same time, the evolution of these modern eukaryotic taxa has influenced both the structure of marine food webs and global biogeochemical cycles.

@article{doi101146annurevecolsys35112202130137,
    author = "Katz, Miriam and Finkel, Zoe V. and Grzebyk, Daniel and Knoll, Andrew H. and Falkowski, Paul G.",
    title = "Evolutionary Trajectories and Biogeochemical Impacts of Marine Eukaryotic Phytoplankton",
    year = "2004",
    journal = "Annual Review of Ecology Evolution and Systematics",
    abstract = "▪ Abstract The evolutionary succession of marine photoautotrophs began with the origin of photosynthesis in the Archean Eon, perhaps as early as 3.8 billion years ago. Since that time, Earth's atmosphere, continents, and oceans have undergone substantial cyclic and secular physical, chemical, and biological changes that selected for different phytoplankton taxa. Early in the history of eukaryotic algae, between 1.6 and 1.2 billion years ago, an evolutionary schism gave rise to “green” (chlorophyll b–containing) and “red” (chlorophyll c–containing) plastid groups. Members of the “green” plastid line were important constituents of Neoproterozoic and Paleozoic oceans, and, ultimately, one green clade colonized land. By the mid-Mesozoic, the green line had become ecologically less important in the oceans. In its place, three groups of chlorophyll c–containing eukaryotes, the dinoflagellates, coccolithophorids, and diatoms, began evolutionary trajectories that have culminated in ecological dominance in the contemporary oceans. Breakup of the supercontinent Pangea, continental shelf flooding, and changes in ocean redox chemistry may all have contributed to this evolutionary transition. At the same time, the evolution of these modern eukaryotic taxa has influenced both the structure of marine food webs and global biogeochemical cycles.",
    url = "https://doi.org/10.1146/annurev.ecolsys.35.112202.130137",
    doi = "10.1146/annurev.ecolsys.35.112202.130137",
    openalex = "W2166890315",
    references = "doi1010160146638088901155, doi102687999013"
}

@article{bottjer2005geobiology,
    author = "Bottjer, David J.",
    title = "Geobiology and the fossil record: eukaryotes, microbes, and their interactions",
    year = "2005",
    journal = "Palaeogeography, Palaeoclimatology, Palaeoecology",
    url = "https://doi.org/10.1016/j.palaeo.2004.10.011",
    doi = "10.1016/j.palaeo.2004.10.011",
    number = "1-2",
    openalex = "W2075109378",
    pages = "5-21",
    volume = "219",
    references = "doi1010079783662033777, doi1010160012825273900287, doi101017cbo9780511601064, doi101017s0094837300003778, doi101093oso97801985491780010001, doi101126science2735277924, doi101126science28454232129, doi1023071483846, doi1023073037993, doi105860choice300309"
}

ABSTRACT The earliest record of animals (Metazoa) consists of trace and body fossils restricted to the last 35 Myr of the Precambrian. It has been proposed that animals arose much earlier and underwent significant evolution as a cryptic fauna; however, the need for any unrecorded prelude of significant duration has been disputed. In this context, we consider recent published research on the nature and chronology of the earliest fossil record of metazoans and on the molecular‐based analysis that yielded older dates for the appearance of major animal groups. We review recent work on the climatic, geochemical, and ecological events that preceded animal fossils and consider their portent for metazoan evolution. We also discuss inferences about the physiology and gene content of the last common ancestor of animals and their closest unicellular relatives. We propose that the recorded Precambrian evolution of animals includes three intervals of advancement that begin with sponge‐grade organisms, and that any preceding cryptic fauna would be no more complex than sponges. The molecular data do not require that more complex animals appeared well before the recognized fossil record; nor, however, do they rule the possibility out, particularly if the interval of simpler metazoan ancestors lasted no more than about 100 or 200 Myr. The geological record of abrupt changes in climate, biogeochemistry, and phytoplankton diversity can be taken to be the result of changes in the carbon cycle triggered by the appearance and diversification of metazoans in an organic carbon‐rich ocean, but as yet no compelling evidence exists for this interpretation. By the end of this cryptic period, animals would already have possessed sophisticated systems of cell–cell signalling, adhesion, apoptosis, and segregated germ cells, possibly with a rudimentary body plan based on anterior–posterior organization. The controls on the timing and tempo of the earliest steps in metazoan evolution are unknown, but it seems likely that oxygen was a key factor in later diversification and increase in body size. We consider several recent scenarios describing how oxygen increased near the end of the Precambrian and propose that grazing and filter‐feeding animals depleted a marine reservoir of suspended organic matter, releasing a microbial ‘clamp’ on atmospheric oxygen.

@article{doi101111j14724669200700125x,
    author = "Gaidos, Eric and DuBuc, Timothy Q. and Dunford, Michael D. and McAndrew, Patrick and PADILLA‐GAMIÑO, J. and Studer, Bruno and Weersing, K. and Stanley, Steven M.",
    title = "The Precambrian emergence of animal life: a geobiological perspective",
    year = "2007",
    journal = "Geobiology",
    abstract = "ABSTRACT The earliest record of animals (Metazoa) consists of trace and body fossils restricted to the last 35 Myr of the Precambrian. It has been proposed that animals arose much earlier and underwent significant evolution as a cryptic fauna; however, the need for any unrecorded prelude of significant duration has been disputed. In this context, we consider recent published research on the nature and chronology of the earliest fossil record of metazoans and on the molecular‐based analysis that yielded older dates for the appearance of major animal groups. We review recent work on the climatic, geochemical, and ecological events that preceded animal fossils and consider their portent for metazoan evolution. We also discuss inferences about the physiology and gene content of the last common ancestor of animals and their closest unicellular relatives. We propose that the recorded Precambrian evolution of animals includes three intervals of advancement that begin with sponge‐grade organisms, and that any preceding cryptic fauna would be no more complex than sponges. The molecular data do not require that more complex animals appeared well before the recognized fossil record; nor, however, do they rule the possibility out, particularly if the interval of simpler metazoan ancestors lasted no more than about 100 or 200 Myr. The geological record of abrupt changes in climate, biogeochemistry, and phytoplankton diversity can be taken to be the result of changes in the carbon cycle triggered by the appearance and diversification of metazoans in an organic carbon‐rich ocean, but as yet no compelling evidence exists for this interpretation. By the end of this cryptic period, animals would already have possessed sophisticated systems of cell–cell signalling, adhesion, apoptosis, and segregated germ cells, possibly with a rudimentary body plan based on anterior–posterior organization. The controls on the timing and tempo of the earliest steps in metazoan evolution are unknown, but it seems likely that oxygen was a key factor in later diversification and increase in body size. We consider several recent scenarios describing how oxygen increased near the end of the Precambrian and propose that grazing and filter‐feeding animals depleted a marine reservoir of suspended organic matter, releasing a microbial ‘clamp’ on atmospheric oxygen.",
    url = "https://doi.org/10.1111/j.1472-4669.2007.00125.x",
    doi = "10.1111/j.1472-4669.2007.00125.x",
    openalex = "W2135979056",
    references = "bottjer2005geobiology, doi101016b9781483227344500176, doi101029jc086ic10p09776, doi10103837918, doi101038418244a, doi101038nature03481, doi101046j13653121200200408x, doi101093bioinformatics183502, doi101126science1065889, doi101126science1107765, doi101126science28153811342"
}

The discipline-wide effort to database the fossil record at the occurrence level has made it possible to estimate marine invertebrate extinction and origination rates with much greater accuracy. The new data show that two biotic mechanisms have hastened recoveries from mass extinctions and confined diversity to a relatively narrow range over the past 500 million years (Myr). First, a drop in diversity of any size correlates with low extinction rates immediately afterward, so much so that extinction would almost come to a halt if diversity dropped by 90%. Second, very high extinction rates are followed by equally high origination rates. The two relationships predict that the rebound from the current mass extinction will take at least 10 Myr, and perhaps 40 Myr if it rivals the Permo-Triassic catastrophe. Regardless, any large event will result in a dramatic ecological and taxonomic restructuring of the biosphere. The data also confirm that extinction and origination rates both declined through the Phanerozoic and that several extinctions in addition to the Permo-Triassic event were particularly severe. However, the trend may be driven by taxonomic biases and the rates vary in accord with a simple log normal distribution, so there is no sharp distinction between background and mass extinctions. Furthermore, the lack of any significant autocorrelation in the data is inconsistent with macroevolutionary theories of periodicity or self-organized criticality.

@article{doi101073pnas0802597105,
    author = "Alroy, John",
    title = "Dynamics of origination and extinction in the marine fossil record",
    year = "2008",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "The discipline-wide effort to database the fossil record at the occurrence level has made it possible to estimate marine invertebrate extinction and origination rates with much greater accuracy. The new data show that two biotic mechanisms have hastened recoveries from mass extinctions and confined diversity to a relatively narrow range over the past 500 million years (Myr). First, a drop in diversity of any size correlates with low extinction rates immediately afterward, so much so that extinction would almost come to a halt if diversity dropped by 90\%. Second, very high extinction rates are followed by equally high origination rates. The two relationships predict that the rebound from the current mass extinction will take at least 10 Myr, and perhaps 40 Myr if it rivals the Permo-Triassic catastrophe. Regardless, any large event will result in a dramatic ecological and taxonomic restructuring of the biosphere. The data also confirm that extinction and origination rates both declined through the Phanerozoic and that several extinctions in addition to the Permo-Triassic event were particularly severe. However, the trend may be driven by taxonomic biases and the rates vary in accord with a simple log normal distribution, so there is no sharp distinction between background and mass extinctions. Furthermore, the lack of any significant autocorrelation in the data is inconsistent with macroevolutionary theories of periodicity or self-organized criticality.",
    url = "https://doi.org/10.1073/pnas.0802597105",
    doi = "10.1073/pnas.0802597105",
    openalex = "W2075331526",
    references = "doi101017s0094837300003778, doi101017s0094837300004917, doi101017s0094837300006539, doi101073pnas111144698, doi101073pnas813801, doi101126science1156963, doi101666009483731999251mditer20co2, doi1016660094837320040300522oeamdo20co2, doi1016660094837320050310006poaeit20co2"
}

@incollection{clary2011geobiological,
    author = "Clary, Renee M. and Wandersee, James H.",
    title = "Geobiological opportunities to learn at U.S. fossil parks",
    year = "2011",
    booktitle = "Qualitative Inquiry in Geoscience Education Research",
    url = "https://doi.org/10.1130/2011.2474(09)",
    doi = "10.1130/2011.2474(09)",
    openalex = "W2503703388"
}

@book{crossref2013palaeobiology,
    title = "Palaeobiology and Geobiology of Fossil Lagerstätten through Earth History",
    year = "2013",
    url = "https://doi.org/10.17875/gup2013-229",
    doi = "10.17875/gup2013-229",
    openalex = "W1246751014"
}

This paper addresses the taphonomic processes responsible for fossil preservation in calcium phosphate, or phosphatization. Aside from silicification and rarer examples of carbonaceous compression, phosphatization is the only taphonomic mode claimed to preserve putative subcellular structures. Because this fossilization window can record such valuable information, a comprehensive understanding of its patterns of occurrence and the geochemical processes involved in the replication of soft tissues are critical endeavors. Fossil phosphatization was most abundant during the latest Neoproterozoic through the early Paleozoic, coinciding with the decline of non-pelletal phosphorite deposits. Its temporal abundance during this timeframe makes it a particularly valuable window for the study of early animal evolution. Several occurrences of phosphatization from the Ediacaran through the Permian Period, including Doushantuo-type preservation of embryo-like fossils and acritarchs, phosphatized gut tracts within Burgess Shale-type carbonaceous compressions, Orsten-type preservation of meiofaunas, and other cases from the later Paleozoic are reviewed. In addition, a comprehensive description of the geochemical controls of calcium phosphate precipitation from seawater is provided, with a focus on the rates of phosphate nucleation and growth, favorable nucleation substrates, and properties of substrate tissue and pore-fluid chemistry. It is hoped that the paleontological and geochemical summaries provided here offer a practical and valuable guide to the Neoproterozoic–Paleozoic phosphatization window.

@article{doi101017s1089332600002801,
    author = "Schiffbauer, James D. and Wallace, Adam F. and Broce, Jesse S. and Xiao, Shuhai",
    title = "Exceptional Fossil Conservation through Phosphatization",
    year = "2014",
    journal = "The Paleontological Society Papers",
    abstract = "This paper addresses the taphonomic processes responsible for fossil preservation in calcium phosphate, or phosphatization. Aside from silicification and rarer examples of carbonaceous compression, phosphatization is the only taphonomic mode claimed to preserve putative subcellular structures. Because this fossilization window can record such valuable information, a comprehensive understanding of its patterns of occurrence and the geochemical processes involved in the replication of soft tissues are critical endeavors. Fossil phosphatization was most abundant during the latest Neoproterozoic through the early Paleozoic, coinciding with the decline of non-pelletal phosphorite deposits. Its temporal abundance during this timeframe makes it a particularly valuable window for the study of early animal evolution. Several occurrences of phosphatization from the Ediacaran through the Permian Period, including Doushantuo-type preservation of embryo-like fossils and acritarchs, phosphatized gut tracts within Burgess Shale-type carbonaceous compressions, Orsten-type preservation of meiofaunas, and other cases from the later Paleozoic are reviewed. In addition, a comprehensive description of the geochemical controls of calcium phosphate precipitation from seawater is provided, with a focus on the rates of phosphate nucleation and growth, favorable nucleation substrates, and properties of substrate tissue and pore-fluid chemistry. It is hoped that the paleontological and geochemical summaries provided here offer a practical and valuable guide to the Neoproterozoic–Paleozoic phosphatization window.",
    url = "https://doi.org/10.1017/s1089332600002801",
    doi = "10.1017/s1089332600002801",
    openalex = "W2935096286",
    references = "doi101017s1089332600002837, doi101111j150239311991tb01488x, doi101111j1525142x201200562x"
}

An extraordinarily well preserved, 600-million-year (Myr)-old, three-dimensionally phosphatized fossil displaying multiple independent characters of modern adult sponges has been analyzed by SEM and synchrotron X-ray tomography. The fossilized animal (Eocyathispongia qiania gen. et sp. nov.) is slightly more than 1.2 mm wide and 1.1 mm tall, is composed of hundreds of thousands of cells, and has a gross structure consisting of three adjacent hollow tubes sharing a common base. The main tube is crowned with a large open funnel, and the others end in osculum-like openings to the exterior. The external surface is densely covered with flat tile-like cells closely resembling sponge pinacocytes, and this layer is punctuated with smaller pores. A dense patch of external structures that display the form of a lawn of sponge papillae has also survived. Within the main funnel, an area where features of the inner surface are preserved displays a regular pattern of uniform pits. Many of them are surrounded individually by distinct collars, mounted in a supporting reticulum. The possibility cannot be excluded that these pits are the remains of a field of choanocytes. The character set evinced by this specimen, ranging from general anatomy to cell type, uniquely indicates that this specimen is a fossil of probable poriferan affinity. So far, we have only this single specimen, and although its organized and complex cellular structure precludes any reasonable interpretation that its origin is abiogenic, confirmation that it is indeed a fossilized sponge will clearly require discovery of additional specimens.

@article{doi101073pnas1414577112,
    author = "Yin, Zongjun and Zhu, Maoyan and Davidson, Eric H. and Bottjer, David J. and Zhao, Fangchen and Tafforeau, Paul",
    title = "Sponge grade body fossil with cellular resolution dating 60 Myr before the Cambrian",
    year = "2015",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "An extraordinarily well preserved, 600-million-year (Myr)-old, three-dimensionally phosphatized fossil displaying multiple independent characters of modern adult sponges has been analyzed by SEM and synchrotron X-ray tomography. The fossilized animal (Eocyathispongia qiania gen. et sp. nov.) is slightly more than 1.2 mm wide and 1.1 mm tall, is composed of hundreds of thousands of cells, and has a gross structure consisting of three adjacent hollow tubes sharing a common base. The main tube is crowned with a large open funnel, and the others end in osculum-like openings to the exterior. The external surface is densely covered with flat tile-like cells closely resembling sponge pinacocytes, and this layer is punctuated with smaller pores. A dense patch of external structures that display the form of a lawn of sponge papillae has also survived. Within the main funnel, an area where features of the inner surface are preserved displays a regular pattern of uniform pits. Many of them are surrounded individually by distinct collars, mounted in a supporting reticulum. The possibility cannot be excluded that these pits are the remains of a field of choanocytes. The character set evinced by this specimen, ranging from general anatomy to cell type, uniquely indicates that this specimen is a fossil of probable poriferan affinity. So far, we have only this single specimen, and although its organized and complex cellular structure precludes any reasonable interpretation that its origin is abiogenic, confirmation that it is indeed a fossilized sponge will clearly require discovery of additional specimens.",
    url = "https://doi.org/10.1073/pnas.1414577112",
    doi = "10.1073/pnas.1414577112",
    openalex = "W2012437090",
    references = "doi10100797894017960023, doi101111brv12090, doi101111j1525142x201200562x"
}

Oxygen-dependent microbial oxidation of sulfur compounds leads to the acidification of natural waters. How acidophiles and their acidic habitats evolved, however, is largely unknown. Using 16S rRNA gene abundance and composition data from 72 hot springs in Yellowstone National Park, Wyoming, we show that hyperacidic (pH<3.0) hydrothermal ecosystems are dominated by a limited number of archaeal lineages with an inferred ability to respire O2. Phylogenomic analyses of 584 existing archaeal genomes revealed that hyperacidophiles evolved independently multiple times within the Archaea, each coincident with the emergence of the ability to respire O2, and that these events likely occurred in the recent evolutionary past. Comparative genomic analyses indicated that archaeal thermoacidophiles from independent lineages are enriched in similar protein-coding genes, consistent with convergent evolution aided by horizontal gene transfer. Because the generation of acidic environments and their successful habitation characteristically require O2, these results suggest that thermoacidophilic Archaea and the acidity of their habitats co-evolved after the evolution of oxygenic photosynthesis. Moreover, it is likely that dissolved O2 concentrations in thermal waters likely did not reach levels capable of sustaining aerobic thermoacidophiles and their acidifying activity until \textasciitilde 0.8 Ga, when present day atmospheric levels were reached, a time period that is supported by our estimation of divergence times for archaeal thermoacidophilic clades.

@article{colman2018geobiological,
    author = "Colman, Daniel R and Poudel, Saroj and Hamilton, Trinity L and Havig, Jeff R and Selensky, Matthew J and Shock, Everett L and Boyd, Eric S",
    title = "Geobiological feedbacks and the evolution of thermoacidophiles",
    year = "2018",
    journal = "The ISME Journal",
    abstract = "Oxygen-dependent microbial oxidation of sulfur compounds leads to the acidification of natural waters. How acidophiles and their acidic habitats evolved, however, is largely unknown. Using 16S rRNA gene abundance and composition data from 72 hot springs in Yellowstone National Park, Wyoming, we show that hyperacidic (pH\<3.0) hydrothermal ecosystems are dominated by a limited number of archaeal lineages with an inferred ability to respire O2. Phylogenomic analyses of 584 existing archaeal genomes revealed that hyperacidophiles evolved independently multiple times within the Archaea, each coincident with the emergence of the ability to respire O2, and that these events likely occurred in the recent evolutionary past. Comparative genomic analyses indicated that archaeal thermoacidophiles from independent lineages are enriched in similar protein-coding genes, consistent with convergent evolution aided by horizontal gene transfer. Because the generation of acidic environments and their successful habitation characteristically require O2, these results suggest that thermoacidophilic Archaea and the acidity of their habitats co-evolved after the evolution of oxygenic photosynthesis. Moreover, it is likely that dissolved O2 concentrations in thermal waters likely did not reach levels capable of sustaining aerobic thermoacidophiles and their acidifying activity until \textasciitilde 0.8 Ga, when present day atmospheric levels were reached, a time period that is supported by our estimation of divergence times for archaeal thermoacidophilic clades.",
    url = "https://doi.org/10.1038/ismej.2017.162",
    doi = "10.1038/ismej.2017.162",
    number = "1",
    openalex = "W2761772040",
    pages = "225-236",
    volume = "12",
    references = "doi101038msb201175, doi101038nature02340, doi101038nature13068, doi101093bioinformaticsbts565, doi101093bioinformaticsbtu033, doi101093molbevmst024, doi101093molbevmsw054, doi101098rstb20061838, doi101126science1153213, doi101126science2895480756"
}

The fossil content of building and decorative stones is used to communicate a wide range of geological knowledge, namely the history of the Earth, plate tectonics, evolutionary patterns and climate change, to nonexpert audiences. Storytelling and narratives are employed to improve the level of interpretation of palaeontological geoheritage. Seven rock types, five of which are highly fossiliferous, widely utilized in most recognizable monuments of the city of Poznań in Poland are employed to produce a complex narrative that guides the individual from the Ordovician to the Neogene period. The narrative is accompanied by rich visuals (graphic reconstructions of ancient ecosystems and now-extinct organisms, palaeogeographical maps) available in four printed and online leaflets and guides, supplemented by a museum exhibition where additional rocks and complete fossil specimens are shown and by workshops for more deeply interested participants. The narrative component of the project allows the detection of the most common misconceptions related to the Earth sciences and strengthens the engagement of individuals involved in the project. The project is developed further with self-guided walks around other Polish cities.

@article{doi101007s12371019004002,
    author = "Wolniewicz, Paweł",
    title = "Bringing the History of the Earth to the Public by Using Storytelling and Fossils from Decorative Stones of the City of Poznań, Poland",
    year = "2019",
    journal = "Geoheritage",
    abstract = "The fossil content of building and decorative stones is used to communicate a wide range of geological knowledge, namely the history of the Earth, plate tectonics, evolutionary patterns and climate change, to nonexpert audiences. Storytelling and narratives are employed to improve the level of interpretation of palaeontological geoheritage. Seven rock types, five of which are highly fossiliferous, widely utilized in most recognizable monuments of the city of Poznań in Poland are employed to produce a complex narrative that guides the individual from the Ordovician to the Neogene period. The narrative is accompanied by rich visuals (graphic reconstructions of ancient ecosystems and now-extinct organisms, palaeogeographical maps) available in four printed and online leaflets and guides, supplemented by a museum exhibition where additional rocks and complete fossil specimens are shown and by workshops for more deeply interested participants. The narrative component of the project allows the detection of the most common misconceptions related to the Earth sciences and strengthens the engagement of individuals involved in the project. The project is developed further with self-guided walks around other Polish cities.",
    url = "https://doi.org/10.1007/s12371-019-00400-2",
    doi = "10.1007/s12371-019-00400-2",
    openalex = "W2969869266",
    references = "doi101007s123710140116x"
}

@inproceedings{andkodner2021prasinophyte,
    author = "Kodner, Robin and Cohen, Phoebe",
    title = "PRASINOPHYTE GREEN ALGAE AND THEIR MICROFOSSIL ANALOGS: GEOBIOLOGICAL IMPLICATIONS",
    year = "2021",
    booktitle = "Geological Society of America Abstracts with Programs",
    url = "https://doi.org/10.1130/abs/2021am-370556",
    doi = "10.1130/abs/2021am-370556",
    openalex = "W3210353353"
}

In the United States of America, fossil park sites provide visitors with sustainable fossil collecting opportunities as well as informal educational instruction via signage, brochures, or paleontological mentors. This unique geotourism venue allows visitors to collect personal fossils and learn about fossilization, geologic time, and evolution – and, at most sites, sea level and climate changes. This investigation researched two fossil park sites in Texas, USA and analyzed visitors' experiences at each site. Ladonia Fossil Park and Mineral Wells Fossil Park were also compared on the Fossil Park Model. Texas fossil parks can effectively educate visitors about multiple earth science concepts, with one site (Mineral Wells) providing consistent and higher quality instruction through its permanent signage. Importantly, fossil parks can serve as informal venues to address content of some of the US National Science Foundation's critical research questions for the next decade. Fossil parks promote geotourism and raise visitor awareness and visibility of local geoheritage, thereby promoting public conservation and sustainability. This research has implications for optimizing global geoheritage sites through effective pre-visit websites, onsite educational opportunities, and optimization of educational content to address modern issues.

@article{doi101016jijgeop202012009,
    author = "Clary, Renee M.",
    title = "A critical review of Texas, USA fossile park sites and implications for global geoheritage sites",
    year = "2021",
    journal = "International Journal of Geoheritage and Parks",
    abstract = "In the United States of America, fossil park sites provide visitors with sustainable fossil collecting opportunities as well as informal educational instruction via signage, brochures, or paleontological mentors. This unique geotourism venue allows visitors to collect personal fossils and learn about fossilization, geologic time, and evolution – and, at most sites, sea level and climate changes. This investigation researched two fossil park sites in Texas, USA and analyzed visitors' experiences at each site. Ladonia Fossil Park and Mineral Wells Fossil Park were also compared on the Fossil Park Model. Texas fossil parks can effectively educate visitors about multiple earth science concepts, with one site (Mineral Wells) providing consistent and higher quality instruction through its permanent signage. Importantly, fossil parks can serve as informal venues to address content of some of the US National Science Foundation's critical research questions for the next decade. Fossil parks promote geotourism and raise visitor awareness and visibility of local geoheritage, thereby promoting public conservation and sustainability. This research has implications for optimizing global geoheritage sites through effective pre-visit websites, onsite educational opportunities, and optimization of educational content to address modern issues.",
    url = "https://doi.org/10.1016/j.ijgeop.2020.12.009",
    doi = "10.1016/j.ijgeop.2020.12.009",
    openalex = "W3120977064",
    references = "doi101007978981154956411"
}