Claim CC214:
There are no transitional fossils between reptiles and birds.
Source:
Watchtower Bible and Tract Society, 1985. Life--How Did It Get Here?
Brooklyn, NY, 75.
Response:
- Many new bird fossils have been discovered in the last couple of
decades, revealing several intermediates between theropod dinosaurs
(such as Allosaurus) and modern birds:
- Sinosauropteryx prima. A dinosaur covered with primitive feathers,
but structurally similar to unfeathered dinosaurs Ornitholestes
and
Compsognathus (Chen et al. 1998; Currie and Chen 2001).
- Ornithomimosaurs, therizinosaurs, and oviraptorosaurs. The
oviraptorosaur Caudipteryx had a body covering of tufted feathers
and had feathers with a central rachis on its wings and tail (Ji et
al. 1998).
Feathers are also known from the therizinosaur Beipiaosaurus (Xu
et
al. 1999a).
Several other birdlike characters appear in these dinosaurs,
including unserrated teeth, highly pneumatized skulls and vertebrae,
and elongated wings. Oviraptorids also had birdlike eggs and
brooding habits (Clark et al. 1999).
- Deinonychosaurs (troodontids and dromaeosaurs). These are the
closest known dinosaurs to birds. Sinovenator, the most primitive
troodontid, is especially similar to Archaeopteryx (Xu et al.
2002). Byronosaurus, another troodontid, had teeth nearly
identical to primitive birds (Makovicky et al. 2003).
Microraptor,
the most primitive dromaeosaur, is also the most birdlike; specimens
have been found with undisputed feathers on their wings, legs, and
tail (Hwang et al. 2002; Xu et al. 2003).
Sinornithosaurus also was covered with a variety of feathers and
had a skull more birdlike than later dromaeosaurs (Xu, Wang, and Wu
1999; Xu and Wu 2001; Xu et al. 2001).
- Protarchaeopteryx, alvarezsaurids, Yixianosaurus and
Avimimus.
These are birdlike dinosaurs of uncertain placement, each potentially
closer to birds than deinonychosaurs are. Protarchaeopteryx has
tail feathers, uncompressed teeth, and an elongated manus (hand/wing)
(Ji et al. 1998).
Yixianosaurus has an indistinctly preserved feathery covering and
hand/wing proportions close to birds (Xu and Wang 2003).
Alvarezsaurids (Chiappe et al. 2002)
and Avimimus (Vickers-Rich et al. 2002) have other birdlike
features.
- Archaeopteryx. This famous fossil is
defined to be a
bird, but it is actually less birdlike in some ways than some genera
mentioned above (Paul 2002; Maryanska et al. 2002).
- Shenzhouraptor (Zhou and Zhang 2002),
Rahonavis (Forster et al. 1998), Yandangornis and
Jixiangornis.
All of these birds were slightly more advanced than Archaeopteryx,
especially in characters of the vertebrae, sternum, and wing bones.
- Sapeornis (Zhou and Zhang 2003), Omnivoropteryx, and
confuciusornithids (e.g., Confuciusornis and
Changchengornis;
Chiappe et al. 1999). These were the first birds to possess large
pygostyles (bone formed from fused tail vertebrae). Other new
birdlike characters include seven sacral vertebrae, a sternum with a
keel (some species), and a reversed hallux (hind toe).
- Enantiornithines, including at least nineteen species of primitive
birds, such as Sinornis (Sereno and Rao 1992; Sereno et al. 2002),
Gobipteryx (Chiappe et al. 2001), and Protopteryx (Zhang and
Zhou
2000). Several birdlike features appeared in enantiornithines,
including twelve or fewer dorsal vertebrae, a narrow V-shaped furcula
(wishbone), and reduction in wing digit bones.
- Patagopteryx, Apsaravis, and yanornithids (Chiappe 2002; Clarke
and Norell 2002).
More birdlike features appeared in this group, including changes to
vertebrae and development of the sternal keel.
- Hesperornis, Ichthyornis, Gansus, and Limenavis.
These
birds are almost as advanced as modern species. New features
included the loss of most teeth and changes to leg bones.
- Modern birds.
References:
- Chen, P., Z. Dong and S. Zhen, 1998. An exceptionally
well-preserved theropod dinosaur from the Yixian Formation of China.
Nature 391: 147-152.
- Chiappe, L. M., 2002. Osteology of the flightless Patagopteryx
deferrariisi from the Late Cretaceous of Patagonia (Argentina). In
Chiappe and Witmer, pp. 281-316.
- Chiappe, L. M. and L. M. Witmer (eds.), Mesozoic Birds: Above the
Heads of Dinosaurs. Berkeley: Univ. of California Press.
- Chiappe, L. M., M. A. Norell and J. M. Clark, 2001. A new skull of
Gobipteryx minuta (Aves: Enantiornithes) from the Cretaceous of the
Gobi Desert. American Museum Novitates 3346: 1-15.
http://diglib1.amnh.org/novitates/i0003-0082-346-01-0001.pdf
- Chiappe, L. M., M. A. Norell and J. M. Clark, 2002. The Cretaceous,
short-armed Alvarezsauridae. In: Chiappe and Witmer, pp. 87-120.
- Chiappe, L. M., S. Ji, Q. Ji and M. A. Norell, 1999. Anatomy and
systematics of the Confuciusornithidae (Theropoda: Aves) from the Late
Mesozoic of northeastern China. Bulletin of the American Museum of
Natural History 242: 1-89.
http://diglib1.amnh.org/bulletins/i0003-0090-242-01-0001.pdf
- Clark, J. M., M. A. Norell and L. M. Chiappe, 1999. An oviraptorid
skeleton from the Late Cretaceous of Ukhaa Tolgod, Mongolia, preserved
in an avianlike brooding position over an oviraptorid nest. American
Museum Novitates 3265: 1-36.
- Clarke, J. A. and M. A. Norell, 2002. The morphology and phylogenetic
position of Apsaravis ukhaana from the late Cretaceous of Mongolia.
American Museum Novitates 3387: 1-46.
http://diglib1.amnh.org/novitates/i0003-0082-3387-01-0001.pdf
- Currie, P. J. and P. Chen, 2001. Anatomy of Sinosauropteryx prima
from Liaoning, northeastern China. Canadian Journal of Earth
Sciences 38: 1705-1727.
- Forster, C. A., S. D. Sampson, L. M. Chiappe and D. W. Krause, 1998.
The theropod ancestry of birds: New evidence from the Late Cretaceous
of Madagascar. Science 279: 1915-1919.
- Hwang, S. H., M. A. Norell, Ji Q. and Gao K., 2002. New specimens of
Microraptor zhaoianus (Theropoda: Dromaeosauridae) from northeastern
China. American Museum Novitates 3381: 1-44.
http://research.amnh.org/users/sunny/hwang.et.al.2002.pdf
- Ji, Q., P. Currie, M. A. Norell and S-A. Ji, 1998. Two feathered
dinosaurs from northeastern China. Nature 393: 753-761.
- Makovicky, P. J., M. A. Norell, J. M. Clark and T. Rowe, 2003.
Osteology and relationships of Byronosaurus jaffei (Theropoda:
Troodontidae). American Museum Novitates 3402, 1-32.
http://diglib1.amnh.org/novitates/i0003-0082-3402-01-0001.pdf
- Maryanska, T., H. Osmólska and M. Wolsan, 2002. Avialan status
for oviraptorosauria. Acta Palaeontologica Polonica 47(1): 97-116.
http://app.pan.pl/acta47/app47-097.pdf
- Paul, Gregory S., 2002. Dinosaurs of the Air. Baltimore: Johns
Hopkins University Press.
- Sereno, P. C. and C. Rao, 1992. Early evolution of avian flight and
perching: New evidence from the Lower Creates of China. Science
255: 845-848.
- Sereno, P. C., C. Rao and J. Li, 2002. Sinornis santensis (Aves:
Enantiornithes) from the Early Cretaceous of Northeastern China. In:
Chiappe and Witmer, pp. 184-208.
- Vickers-Rich, P., L. M. Chiappe and S. Kurzanov, 2002. The enigmatic
birdlike dinosaur Avimimus portentosus. In: Chiappe and Witmer,
pp. 65-86.
- Xu, X. and X. Wang, 2003. A new maniraptorian dinosaur from the Early
Cretaceous Yixian Formation of Western Liaoning. Vertebrate
Palasiatica 41(3): 195-202.
- Xu, X. and X-C. Wu, 2001. Cranial morphology of Sinornithosaurus
millenii Xu et al. 1999 (Dinosauria: Theropoda: Dromaeosauridae) from
the Yixian Formation of Liaoning, China. Canadian Journal of Earth
Sciences 38: 1739-1752.
- Xu, X., Z. Tang and X. Wang, 1999a. A therizinosaurid dinosaur with
integumentary structures from China. Nature 399: 350-354.
- Xu, X., X-L. Wang and X-C. Wu, 1999b. A dromaeosaur dinosaur with a
filamentous integument from the Yixian Formation of China. Nature
401: 262-266.
- Xu, X., Z. Zhou and R. O. Prum, 2001. Branched integumental structures
in Sinornithosaurus and the origin of feathers. Nature 410:
200-204.
- Xu, X., M. A. Norell, X. Wang, P. J. Makovicky and X. Wu, 2002. A
basal troodontid from the Early Cretaceous of China. Nature 415:
780-784.
- Xu, X., Z. Zhou, X. Wang, X. Kuang, F. Zhang and X. Du, 2003.
Four-winged dinosaurs from China. Nature 421: 335-340.
http://www.cals.ncsu.edu/course/zo501/4WingedDino.pdf
- Zhang, F. and Z. Zhou, 2000. A primitive enantiornithine bird and the
origin of feathers. Science 290: 1955-1959.
- Zhou, Z. and F. Zhang, 2002. A long-tailed, seed-eating bird from
the Early Cretaceous of China. Nature 418: 405-409.
- Zhou, Z. and F. Zhang, 2003. Anatomy of the primitive bird Sapeornis
chaoyangensis from the Early Cretaceous of Liaoning, China.
Canadian
Journal of Earth Sciences 40: 731-747.
Further Reading:
Chiappe, L. M. and G. J. Dyke, 2002. The Mesozoic radiation of birds.
Annual Review of Ecology and Systematics 33: 91-124. (technical)
Dingus, L. and T. Rowe, 1997. The mistaken extinction: dinosaur evolution
and the origin of birds. New York: Freeman and Company.
Padian, K. and L. M. Chiappe, 1998. The origin of birds and their flight.
Scientific American 278(2) (Feb.): 38-47.
Paul, Gregory S., 2002. Dinosaurs of the Air. Baltimore: Johns
Hopkins University Press.
Pojeta, John Jr. and Springer, Dale A., 2001. Evolution and the Fossil
Record, American Geological Institute, Alexandria, VA.
http://www.agiweb.org/news/spot_06apr01_evolutionbk.htm
,
http://www.agiweb.org/news/evolution.pdf
.
Prum, Richard O. and Alan H. Brush, 2003. Which came first, the feather
or the bird? Scientific American 288(3) (Mar.): 84-93.
Wang, Justin, 1998. Scientists flock to explore China's 'site of the
century'. Science 279: 1626-1627.
created 2001-4-29, modified 2005-1-14