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Science 1 March 1991:
Vol. 251. no. 4997, pp. 1063 - 1065
DOI: 10.1126/science.251.4997.1063
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Articles

New Fossil Evidence on the Sister-Group of Mammals and Early Mesozoic Faunal Distributions

NEIL H. SHUBIN 1, A. W. CROMPTON 2, HANS-DIETER SUES 3, and PAUL E. OLSEN 4

1 Department of Biology, University of Pennsylvania, Philadelphia, PA 19104
2 Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138
3 Department of Paleobiology, NHB MRC 121, National Museum of Natural History, Washington, DC 20560
4 Lamont-Doherty Geological Observatory of Columbia University, Palisades, N.Y. 10964

Newly discovered remains of highly advanced mammal-like reptiles (Cynodontia: Tritheledontidae) from the Early Jurassic of Nova Scotia, Canada, have revealed that aspects of the characteristic mammalian occlusal pattern are primitive. Mammals and tritheledontids share an homologous pattern of occlusion that is not seen in other cynodonts. The new tritheledontids represent the first definite record of this family from North America. The extreme similarity of North American and African tritheledontids supports the hypothesis that the global distribution of terrestrial tetrapods was homogeneous in the Early Jurassic. This Early Jurassic cosmopolitanism represents the continuation of a trend toward increased global homogeneity among terrestrial tetrapod communities that began in the late Paleozoic.

Submitted on September 10, 1990
Accepted on November 29, 1990


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
ELLIOTHERIUM KERSTENI, A NEW TRITHELEDONTID FROM THE LOWER ELLIOT FORMATION (UPPER TRIASSIC) OF SOUTH AFRICA.
C. A. SIDOR and P. J. HANCOX (2006)
Journal of Paleontology 80, 333-342
   Abstract »    Full Text »    PDF »
A REASSESSMENT OF DIANCHUNGOSAURUS LUFENGENSIS YANG, 1982a, AN ENIGMATIC REPTILE FROM THE LOWER LUFENG FORMATION (LOWER JURASSIC) OF YUNNAN PROVINCE, PEOPLE'S REPUBLIC OF CHINA.
P. M. BARRETT and X. XING (2005)
Journal of Paleontology 79, 981-986
   Abstract »    Full Text »    PDF »


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