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Research Articles

A Swimming Mammaliaform from the Middle Jurassic and Ecomorphological Diversification of Early Mammals

Science
24 Feb 2006
Vol 311, Issue 5764
pp. 1123-1127

Abstract

A docodontan mammaliaform from the Middle Jurassic of China possesses swimming and burrowing skeletal adaptations and some dental features for aquatic feeding. It is the most primitive taxon in the mammalian lineage known to have fur and has a broad, flattened, partly scaly tail analogous to that of modern beavers. We infer that docodontans were semiaquatic, convergent to the modern platypus and many Cenozoic placentals. This fossil demonstrates that some mammaliaforms, or proximal relatives to modern mammals, developed diverse locomotory and feeding adaptations and were ecomorphologically different from the majority of generalized small terrestrial Mesozoic mammalian insectivores.

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Supplementary Material

File (ji_som.pdf)

References and Notes

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Etymology: Castor (Latin), beaver; cauda (Latin), tail; after the broad, flattened, scaly, and beaverlike tail for swimming; lutra (Latin), otter; similis (Latin), similar; similar to extant otters in some dental and vertebral characters. Systematics: Clade Mammaliaformes (Class Mammalia by traditional definition); Order Docodonta; Family incertae sedis; gen. et sp. nov. Castorocauda lutrasimilis. Holotype: Jinzhou Museum of Paleontology, Jinzhou City, Liaoning Province, China (JZMP-04-117), an incomplete, flattened skeleton, partial skull, preserved with fur and scales. Locality and Age: Daohugou locality (N41°18.979′, E119°14.318′), Ningcheng County, Inner Mongolia, China; Jiulongshan Formation, dated to be 164 million years ago (1517).
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We thank Z.-Y. Sun and the Jinzhou Museum of Paleontology for making this specimen available for us to study. We also thank K. C. Beard, M. R. Dawson, T. Martin, N. Rybczynski, and J. R. Wible for numerous discussions; M. R. Dawson for improving the manuscript; M. A. Klingler for assistance with graphics; J. R. Wible for access to collections; and H.-L. You for assistance with this study. We received support from the Chinese Academy of Geological Sciences (Beijing), Ministry of Land Resources of China, Ministry of Science and Technology of China (973 project) (Q.J.); and from the National Science Foundation (USA), National Natural Science Foundation (China), National Geographic Society, and Carnegie Museum of Natural History (Z.-X.L.).

Information & Authors

Information

Published In

Science
Volume 311 | Issue 5764
24 February 2006

Submission history

Received: 28 November 2005
Accepted: 23 January 2006
Published in print: 24 February 2006

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Notes

Supporting Online Material
SOM Text
Matrixes S1 and S2
References

Authors

Affiliations

Qiang Ji
Department of Earth Science, Nanjing University, Nanjing 200017, China.
Chinese Academy of Geological Sciences, Beijing 100037, China.
Zhe-Xi Luo*
Department of Earth Science, Nanjing University, Nanjing 200017, China.
Carnegie Museum of Natural History, Pittsburgh, PA 15213, USA.
Chong-Xi Yuan
Chinese Academy of Geological Sciences, Beijing 100037, China.
Alan R. Tabrum
Carnegie Museum of Natural History, Pittsburgh, PA 15213, USA.

Notes

*
To whom correspondence should be addressed. E-mail: [email protected]

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