Claim CC211:
No fossils have been found transitional between invertebrates and
vertebrates.
Source:
Morris, Henry M. 1985. Scientific Creationism. Green Forest, AR: Master
Books, p. 82
Response:
- There are Cambrian fossils transitional between vertebrate and
invertebrate:
- Pikaia, an early invertebrate chordate. It was at first
interpreted as a segmented worm until a reanalysis showed it had a
notochord.
- Yunnanozoon, an early chordate.
- Haikouella, a chordate similar to Yunnanozoon, but with
additional traits, such as a heart and a relatively larger brain
(Chen et al. 1999).
- Conodont animals had bony teeth, but the rest of their body was
soft. They also had a notochord (Briggs et al. 1983; Sansom et
al. 1992).
- Cathaymyrus diadexus, the oldest known chordate (535 million
years old; Shu et al. 1996).
- Myllokunmingia and Haikouichthys, two early vertebrates that
still lack a clear head and bony skeletons and teeth. They differ
from earlier invertebrate chordates in having a zigzag arrangement
of segmented muscles, and their gill arrangement is more complex
than a simple slit (Monastersky 1999).
- There are living invertebrate chordates (Branchiostoma [Amphioxus],
urochordates [tunicates]) and living basal near-vertebrates (hagfish,
lampreys) that show plausible intermediate forms.
Links:
Monastersky, Richard, 1999. Waking up to the dawn of vertebrates.
Science News 156: 292.
http://www.sciencenews.org/sn_arc99/11_6_99/fob1.htm
References:
- Briggs, D. E. G., E. N. K. Clarkson and R. J. Aldridge, 1983. The
conodont animal. Lethaia 16: 1-14.
- Chen, J.-Y., D.-Y. Huang and C.-W. Li, 1999. An early Cambrian
craniate-like chordate. Nature 402: 518-522.
http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v402/n6761/full/402518a0_r.html
- Monastersky, R., 1999. (see above).
- Sansom, I. J., M. P. Smith, H. A. Armstrong and M. M. Smith, 1992.
Presence of the earliest vertebrate hard tissues in conodonts.
Science 256: 1308-1311.
- Shu, D.-G., S. Conway Morris and X.-L. Zhang, 1996. A Pikaia-like
chordate from the Lower Cambrian of China. Nature 384: 157-158.
Further Reading:
Speer, B. R. 2000. Introduction to the Deuterostomia.
http://www.ucmp.berkeley.edu/phyla/deuterostomia.html
Waggoner, Ben. 1996. Introduction to the Cephalochordata.
http://www.ucmp.berkeley.edu/chordata/cephalo.html
created 2003-7-5
