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A Jurassic eutherian mammal and divergence of marsupials and placentals

Nature volume 476, pages 442–445 (2011)Cite this article

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Abstract

Placentals are the most abundant mammals that have diversified into every niche for vertebrates and dominated the world’s terrestrial biotas in the Cenozoic. A critical event in mammalian history is the divergence of eutherians, the clade inclusive of all living placentals, from the metatherian–marsupial clade1,2,3,4,5,6,7,8. Here we report the discovery of a new eutherian of 160 Myr from the Jurassic of China, which extends the first appearance of the eutherian–placental clade by about 35 Myr from the previous record, reducing and resolving a discrepancy between the previous fossil record and the molecular estimate for the placental–marsupial divergence9,10,11,12,13. This mammal has scansorial forelimb features, and provides the ancestral condition for dental and other anatomical features of eutherians.

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Figure 1: Holotype specimen of Juramaia sinensis , Beijing Museum of Natural History (BMNH) PM1343B.
Figure 2: Dental and mandibular features of Juramaia sinensis (BMNH PM1343B).
Figure 3: Time-calibrated phylogeny of the eutherian Juramaia among other boreosphenidan mammals, and comparative morphology of some key molar features.

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Acknowledgements

We thank A. R. Tabrum for his meticulous preparation of the fossil, Y.-Q. Zhang for casting, and M. A. Klingler for assistance with graphics. During this work, we benefited from discussion with Y.-Q. Liu on field geology and dating, and with R. J. Asher, K. C. Beard, R. L. Cifelli, M. R. Dawson, T. Martin and J. R. Wible for discussion on mammal phylogeny. J. Wible and M. Dawson helped to improve the manuscript. Support was given to Z.-X.L. from the National Science Foundation (USA), to C.-X.Y. from the National Natural Science Foundation-China and the Chinese Academy of Geological Sciences, and to Q.J. from the 973 Project of the Ministry of Science and Technology of China and funding from the Chinese Academy of Geological Sciences.

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Authors and Affiliations

  1. Carnegie Museum of Natural History, Pittsburgh, 15213, Pennsylvania, USA

    Zhe-Xi Luo

  2. Chinese Academy of Geological Sciences, Beijing, 100037, China

    Chong-Xi Yuan & Qiang Ji

  3. Beijing Museum of Natural History, Beijing, 100050, China

    Qing-Jin Meng

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  1. Zhe-Xi Luo
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Contributions

Z.-X.L. and Q.J. designed the research plan. All authors participated in morphological studies. Z.-X.L. and C.-X.Y. performed phylogenetic analyses. Z.-X.L. wrote the paper with discussion from all authors.

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Correspondence to Zhe-Xi Luo.

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Luo, ZX., Yuan, CX., Meng, QJ. et al. A Jurassic eutherian mammal and divergence of marsupials and placentals. Nature 476, 442–445 (2011). https://doi.org/10.1038/nature10291

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