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The earliest known eutherian mammal

Abstract

The skeleton of a eutherian (placental) mammal has been discovered from the Lower Cretaceous Yixian Formation of northeastern China. We estimate its age to be about 125 million years (Myr), extending the date of the oldest eutherian records with skull and skeleton by about 40–50 Myr. Our analyses place the new fossil at the root of the eutherian tree and among the four other known Early Cretaceous eutherians, and suggest an earlier and greater diversification of stem eutherians that occurred well before the molecular estimate for the diversification of extant placental superorders (104–64 Myr). The new eutherian has limb and foot features that are known only from scansorial (climbing) and arboreal (tree-living) extant mammals, in contrast to the terrestrial or cursorial (running) features of other Cretaceous eutherians. This suggests that the earliest eutherian lineages developed different locomotory adaptations, facilitating their spread to diverse niches in the Cretaceous.

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Figure 1: Eomaia scansoria (Chinese Academy of Geological Sciences (CAGS) 01-IG-1a, b; holotype).
Figure 2: Eomaia scansoria dentition and mandible (composite reconstruction).
Figure 3: Comparison of forefoot (manus) of Eomaia scansoria (dorsal view, right).
Figure 4: Comparison of hindfoot (pes) of Eomaia scansoria.
Figure 5: Comparison of manual phalanges and claws of Eomaia scansoria to those of scansorial and arboreal placentals (lateral view of digit 3), a Tree shrew Tupaia (scansorial, after refs 40 and 41).
Figure 6: Phylogeny of eutherian Eomaia scansoria (a) and timing of the earliest evolution of eutherians (b).

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References

  1. McKenna, M. C. & Bell, S. K. Classification of Mammals above the Species Level 1–631 (Columbia Univ. Press, New York, 1997)

    Google Scholar 

  2. Novacek, M. J. Mammalian phylogeny—shaking the tree. Nature 356, 121–125 (1992)

    Article  ADS  CAS  PubMed  Google Scholar 

  3. Novacek, M. J. et al. Epipubic bones in eutherian mammals from the Late Cretaceous of Mongolia. Nature 389, 483–486 (1997)

    Article  ADS  CAS  PubMed  Google Scholar 

  4. Swisher, C. C. III, Wang, Y.-Q., Wang, X.-L., Xu, X. & Wang, Y. Cretaceous age for the feathered dinosaurs of Liaoning, China. Nature 398, 58–61 (1999)

    Article  ADS  Google Scholar 

  5. Gradstein, F. M. et al. in Geochronology, Time Scales and Global Stratigraphic Correlation (eds Berggren, W. A., Kent, D. V., Aubry, M. P. & Hardenbol, J.) 95–126 (Spec. Pub. No. 54, SEPM, Soc. Sed. Geol., Tulsa, Oklahoma, 1995)

    Book  Google Scholar 

  6. Hu, Y.-M., Wang, Y.-Q., Luo, Z.-X. & Li, C.-K. A new symmetrodont mammal from China and its implications for mammalian evolution. Nature 390, 137–142 (1997)

    Article  ADS  CAS  PubMed  Google Scholar 

  7. Hu, Y.-M., Wang, Y.-Q., Li, C.-K. & Luo, Z.-X. Morphology of dentition and forelimb of Zhangheotherium. Vert. Palasiatic. 38, 102–125 (1998)

    Google Scholar 

  8. Ji, Q., Luo, Z.-X. & Ji, S.-A. A Chinese triconodont mammal and mosaic evolution of the mammalian skeleton. Nature 398, 326–330 (1999)

    Article  CAS  PubMed  Google Scholar 

  9. Wang, Y.-Q., Hu, Y.-M., Meng, J. & Li, C.-K. An ossified Meckel's cartilage in two Cretaceous mammals and origin of the mammalian middle ear. Science 294, 357–361 (2001)

    Article  ADS  CAS  PubMed  Google Scholar 

  10. Gee, H. (ed.) Rise of the Dragon-Readings from Nature about the Chinese Fossil Records 1–262 (Univ. Chicago Press, Chicago, 2001)

    Google Scholar 

  11. Kielan-Jaworowska, Z. & Dashzeveg, D. Eutherian mammals from the Early Cretaceous of Mongolia. Zool. Scripta 18, 347–355 (1989)

    Article  Google Scholar 

  12. Sigogneau-Russell, D., Dashzeveg, D. & Russell, D. E. Further data on Prokennalestes (Mammalia Eutheria inc. sed.) from the Early Cretaceous of Mongolia. Zool. Scripta 21, 205–209 (1992)

    Article  Google Scholar 

  13. Averianov, A. O. & Skutschas, P. P. A eutherian mammal from the Early Cretaceous of Russia and biostratigraphy of the Asian Early Cretaceous vertebrate assemblages. Lethaia 33, 330–340 (2000)

    Article  Google Scholar 

  14. Averianov, A. O. & Skutschas, P. P. A new genus of eutherian mammal from the Early Cretaceous of Transbaikalia, Russia. Acta Palaeontol. Pol. 46, 431–436 (2001)

    Google Scholar 

  15. Cifelli, R. L. Tribosphenic mammal from the North American Early Cretaceous. Nature 401, 363–366 (1999)

    ADS  CAS  PubMed  Google Scholar 

  16. Nessov, L. A., Archibald, J. D. & Kielan-Jaworowska, Z. Ungulate-like mammals from the Late Cretaceous of Uzbekistan and a phylogenetic analysis of Ungulatomorpha. Bull. Carnegie Mus. Nat. Hist. 34, 40–88 (1998)

    Google Scholar 

  17. Archibald, J. D., Averianov, A. O. & Ekdale, E. G. Late Cretaceous relatives of rabbits, rodents, and other placental mammals. Nature 414, 62–65 (2001)

    Article  ADS  CAS  PubMed  Google Scholar 

  18. Kielan-Jaworowska, Z. Skull structure in Kennalestes and Asioryctes. Palaeontol. Pol. 42, 25–78 (1981)

    Google Scholar 

  19. McKenna, M. C., Kielan-Jaworowska, Z. & Meng, J. Earliest eutherian mammal skull from the Late Cretaceous (Coniacian) of Uzbekistan. Acta Palaeontol. Pol. 45, 1–54 (2000)

    Google Scholar 

  20. Cifelli, R. L. in Mammal Phylogeny Vol. 1 (eds Szalay, F. S., Novacek, M. J. & McKenna, M. C.) 205–215 (Springer, New York, 1993)

    Book  Google Scholar 

  21. Rougier, G. W., Wible, J. R. & Novacek, M. J. Implications of Deltatheridium specimens for early marsupial history. Nature 396, 459–463 (1998)

    Article  ADS  CAS  PubMed  Google Scholar 

  22. Cifelli, R. L. & Muizon, C. de. Dentition and jaw of Kokopellia juddi, a primitive marsupial or near marsupial from the medial Cretaceous of Utah. J. Mamm. Evol. 4, 241–258 (1997)

    Article  Google Scholar 

  23. Muizon, C. de. Mayulestes ferox, a borhyaenoid (Metatheria, Mammalia) from the early Palaeocene of Bolivia. Phylogenetic and palaeobiological implications. Geodiversitas 20, 19–142 (1998)

    Google Scholar 

  24. Luo, Z.-X., Cifelli, R. L. & Kielan-Jaworowska, Z. Dual origin of tribosphenic mammals. Nature 409, 53–57 (2001)

    Article  ADS  CAS  PubMed  Google Scholar 

  25. Luo, Z.-X., Kielan-Jaworowska, Z. & Cifelli, R. L. In quest for a phylogeny of Mesozoic mammals. Acta Palaeontol. Pol. 47, 1–78 (2002)

    Google Scholar 

  26. Krebs, B. Das Skelett von Henkelotherium guimarotae gen. et sp. nov. (Eupantotheria, Mammalia) aus dem Oberen Jura von Portugal. Berliner Geowiss. Abh. 133, 1–110 (1991)

    Google Scholar 

  27. Rougier, G. W. Vincelestes neuquenianus Bonaparte (Mammalia, Theria), un primitivo mammifero del Cretacico Inferior de la Cuenca Neuqina. Thesis, Univ. Nac. Buenos Aires (1993)

    Google Scholar 

  28. Rich, T. H. et al. A tribosphenic mammal from the Mesozoic of Australia. Science 278, 1438–1442 (1997)

    Article  ADS  CAS  PubMed  Google Scholar 

  29. Rich, T. H. et al. A second tribosphenic mammal from the Mesozoic of Australia. Records Queen Victoria Mus. 110, 1–9 (2001)

    Google Scholar 

  30. Kielan-Jaworowska, Z. Postcranial skeleton in Kennalestes and Asioryctes. Palaeontol. Pol. 37, 65–83 (1977)

    Google Scholar 

  31. Kielan-Jaworowska, Z. Postcranial skeleton in Zalambdalestidae. Palaeontol. Pol. 38, 3–41 (1978)

    Google Scholar 

  32. Horovitz, I. The tarsus of Ukhaatherium nessovi (Eutheria Mammalia) from the Late Cretaceous of Mongolia: an appraisal of the evolution of the ankle in basal therians. J. Vert. Paleontol. 20, 547–560 (2000)

    Article  Google Scholar 

  33. Szalay, F. S. & Trofimov, B. A. The Mongolian Late Cretaceous Asiatherium, and the early phylogeny and paleobiologeography of Metatheria. J. Vert. Paleontol. 16, 474–509 (1996)

    Article  Google Scholar 

  34. Szalay, F. S. Evolutionary History of the Marsupials and an Analysis of Osteological Characters 1–481 (Cambridge Univ. Press, Cambridge, 1994)

    Google Scholar 

  35. Argot, C. Functional-adaptive anatomy of the forelimb in the Didelphidae, and the paleobiology of the Paleocene marsupials Mayulestes ferox and Pucaldelphis andinus. J. Morph. 247, 51–79 (2001)

    Article  CAS  PubMed  Google Scholar 

  36. Kielan-Jaworowska, Z. & Gambaryan, P. P. Postcranial anatomy and habits of Asian multituberculate mammals. Fossils Strata 36, 1–92 (1994)

    Google Scholar 

  37. Krause, D. W. & Jenkins, F. A. Jr The postcranial skeleton of North American multituberculates. Bull. Mus. Comp. Zool. 150, 199–246 (1983)

    Google Scholar 

  38. Rowe, T. B. Definition, diagnosis, and origin of Mammalia. J. Vert. Paleontol. 8, 241–264 (1988)

    Article  Google Scholar 

  39. Meng, J. & Wyss, A. R. Multituberculate and other mammal hair recovered from Palaeogene excreta. Nature 385, 712–714 (1997)

    Article  ADS  CAS  PubMed  Google Scholar 

  40. Beard, K. C. in Primates and Their Relatives in Phylogenetic Perspective (ed. MacPhee, R. D. E.) 63–90 (Plenum, New York, 1992)

    Google Scholar 

  41. Szalay, F. Z. & Lucas, S. G. The postcranial morphology of Paleocene Chriacus and Mixodectes and the phylogenetic relationships of archontan mammals. New Mexico Mus. Nat. Hist. Sci. Bull. 7, 1–47 (1996)

    Google Scholar 

  42. McLeod, N. & Rose, K. D. Inferring locomotory behaviour in Paleogene mammals via eigenshape analysis. Am. J. Sci. 293, 300–355 (1993)

    Article  ADS  Google Scholar 

  43. Jenkins, F. A. Jr in Primate Locomotion (ed. Jenkins, F. A. Jr) 85–116 (Academic, New York, 1974)

    Google Scholar 

  44. Schilling, N. & Fischer, M. S. Kinematic analysis of treadmill locomotion of tree shrews, Tupaia glis (Scandentia: Tupaiidae). Z. Saugetierkd. 64, 129–153 (1999)

    Google Scholar 

  45. Loope, D. B., Dingus, L., Swisher, C. C. III & Minjin, C. Life and death in a Late Cretaceous dunefield, Nemegt Basin Mongolia. Geology 26, 27–30 (1998)

    Article  ADS  Google Scholar 

  46. Murphy, W. J. et al. Resolution of the early placental mammal radiation using Bayesian phylogenetics. Science 294, 2348–2351 (2001)

    Article  ADS  CAS  PubMed  Google Scholar 

  47. Eizirik, E., Murphy, W. J. & O'Brien, S. J. Molecular dating and biogeography of early placental mammal radiation. J. Hered. 92, 212–219 (2001)

    Article  CAS  PubMed  Google Scholar 

  48. Kumar, S. & Hedges, S. B. A molecular timescale for vertebrate evolution. Nature 392, 917–920 (1998)

    Article  ADS  CAS  PubMed  Google Scholar 

  49. Hedges, S. B. & Kumar, S. Technical comments: divergence times of eutherian mammals. Science 285, 2031a (1999)

    Article  Google Scholar 

  50. Foote, M., Hunter, J. P., Janis, C. M. & Sepkoski, J. Jr Evolutionary and preservational constraints on origins of biologic groups: divergence times of eutherian mammals. Science 283, 1310–1314 (1999)

    Article  ADS  CAS  PubMed  Google Scholar 

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Acknowledgements

We thank K.-Q. Gao, M. Ellison, S.-A. Ji, M. A. Norell and D. Ren for collaborative field work; J. D. Archibald, R. L. Cifelli, Z. Kielan-Jaworowska, M. J. Novacek and G. W. Rougier for sharing ideas on early mammal research; K. C. Beard, M. Fischer, D. Gebo, M. Sánchez-Villagra and F. S. Szalay for discussions on limb anatomy and reconstructing locomotory patterns of fossil mammals; M. R. Dawson and A. Weil for improving the paper; A. Henrici for her skilful preparation; and M. Klingler for illustration of Fig. 1. We received funding from the Ministry of Land Resources of People's Republic of China and National Natural Science Foundation of China (Q.J.), National Science Foundation of USA and National Geographic Society (Z.-X.L.), and the Netting/O'Neil Funds of Carnegie Museum (Z.-X.L. and J.R.W.), and Brackenridge Fellowship of the University of Pittsburgh (J.A.G.).

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Ji, Q., Luo, ZX., Yuan, CX. et al. The earliest known eutherian mammal. Nature 416, 816–822 (2002). https://doi.org/10.1038/416816a

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