A new symmetrodont mammal from China and its implications for mammalian evolution

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A new symmetrodont mammal has been discovered in the Mesozoic era (Late Jurassic or Early Cretaceous period) of Liaoning Province, China. Archaic therian mammals, including symmetrodonts, are extinct relatives of the living marsupial and placental therians. However, these archaic therians have been mostly documented by fragmentary fossils. This new fossil taxon, represented by a nearly complete postcranial skeleton and a partial skull with dentition, is the best-preserved symmetrodont mammal yet discovered. It provides a new insight into the relationships of the major lineages of mammals and the evolution of the mammalian skeleton. Our analysis suggests that this new taxon represents a part of the early therian radiation before the divergence of living marsupials and placentals; that therians and multituberculates are more closely related to each other than either group is to other mammalian lineages; that archaic therians lacked the more parasagittal posture of the forelimb of most living therian mammals; and that archaic therians, such as symmetrodonts, retained the primitive feature of a finger-like promontorium (possibly with a straight cochlea) of the non-therian mammals. The fully coiled cochlea evolved later in more derived therian mammals, and is therefore convergent to the partially coiled cochlea of monotremes.

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Figure 1: Zhangheotherium quinquecuspidens (IVPP V7466, holotype).
Figure 2: Dentition and mandible of Zhangheotherium quinquecuspidens.
Figure 3: Reconstruction of the partial basicranium of Zhangheotherium quiquecuspidens (IVPP V7466).
Figure 4: Comparison of the sternal apparatus and pectoral girdle of Zhangheotherium and living mammals.
Figure 5: Phylogenetic relationships of Zhangheotherium quinquecuspidens.


  1. 1

    Wang, Y.-Q., Hu, Y.-M., Zhou, M.-Z. & Li, C.-K. in Sixth Symposium on Mesozoic Terrestrial Ecosystems and Biota, Short Papers (eds Sun, A.-L & Wang, Y.-Q.) 221–227 (China Ocean Press, Beijing, (1995)).

  2. 2

    Chen, P.-J. et al. Studies on the Late Mesozoic continental formations of western Liaoning. Bull. Nanjing Inst. Geol. Palaeontol. Acad. Sin. 1, 22–55 (1980). (In Chinese.)

  3. 3

    Chen, P.-J. & Chang, Z.-L. Nonmarine Cretaceous stratigraphy in eastern China. Cretaceous Res. 15, 245–257 (1994).

  4. 4

    Jin, F. New advances in the Late Mesozoic stratigraphic research of Western Liaoning, China. Vert. PalAsiat. 34, 102–122 (1996).

  5. 5

    Hou, L.-H., Zhou, Z.-H., Martin, L. D. & Feduccia, A. Abeaked bird from the Jurassic of China. Nature 377, 616–618 (1995).

  6. 6

    Hou, L.-H., Martin, L. D., Zhou, Z.-H. & Feduccia, A. Early adaptive radiation of birds: evidence from fossils from Northeastern China. Science 274, 1164–1165 (1996).

  7. 7

    Ji, Q. & Ji, S.-A. Protarchaeopteryx, a new genus of Archaeopteridae of China. Chin. Geol. 1997 (3), 38–41 (1997). (In Chinese.)

  8. 8

    Ji, Q. & Ji, S.-A. Discovery of the earliest bird fossils in China and the origin of birds. Chin. Geol. 1996 (10), 30–33 (1996). (In Chinese.)

  9. 9

    Smith, P. E. et al. Date and rates in ancient lakes: 40Ar–39Ar Evidence for an early Cretaceous age for the Jehol group, Northeast China. Can. J. Earth Sci. 32, 1426–1431 (1995).

  10. 10

    Simpson, G. G. A Catalogue of the Mesozoic Mammalia in the Geological Department of the British Museum (Oxford Univ. Press, London, (1928)).

  11. 11

    Clemens, W. A. Late Jurassic mammalian fossils in the Sedgwick Museum, Cambridge. Palaeontology 6, 373–377 (1963).

  12. 12

    Cassiliano, M. L. & Clemens, W. A. J in Mesozoic Mammals: the First Two-thirds of Mammalian History (eds Lillegraven, J. A., Kielan-Jaworowska, Z. & Clemens, W. A.) 150–161 (Univ. California Press, Berkeley, (1979)).

  13. 13

    Jenkins, F. A. J & Parrington, F. R. Postcranial skeleton of the Triassic mammals Eozostrodon, Megazostrodon, and Erythrotherium. Phil. Trans. R. Soc. Lond. B 273, 387–431 (1976).

  14. 14

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

  15. 15

    Jenkins, F. A. J & Schaff, C. R. The Early Cretaceous mammal Gobiconodon (Mammalia Triconodonta) from the Cloverly Formation in Montana. J. Vert. Paleontol. 6, 1–24 (1988).

  16. 16

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

  17. 17

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

  18. 18

    Sereno, P. & McKenna, M. C. Cretaceous multituberculate skeleton and the early evolution of the mammalian shoulder girdle. Nature 377, 144–147 (1995).

  19. 19

    Fox, R. C. Upper molar structure in the Late Cretaceous symmetrodont Symmetrodontoides Fox, and a classification of the Symmetrodonta (Mammalia). J. Paleontol. 59, 21–26 (1985).

  20. 20

    Cifelli, R. Cretaceous mammals of southern Utah. III. Therian mammals from the Turonian (Early Late Cretaceous). J. Vert. Paleontol. 10, 332–345 (1990).

  21. 21

    Kermack, K. A., Mussett, F. & Rigney, H. W. The skull of Morganucodon. Zool. J. Linn. Soc. 71, 1–158 (1981).

  22. 22

    Crompton, A. W. & Luo, Z. in Mammal Phylogeny (eds Szalay, F. S., Novacek, M. J. & McKenna, M. C.) 30–44 (Springer, New York, (1993)).

  23. 23

    Rougier, G. W., Wible, J. R. & Hopson, J. A. Reconstruction of the cranial vessels in the Early Cretaceous mammal Vincelestes neuquenianus: implications for the evolution of the mammalian cranial vascular system. J. Vert. Paleontol. 12, 188–216 (1992).

  24. 24

    Marshall, L. G. & Muizon, C. d in Pucadelphys andinus (Marsupialia, Mammalia) from the early Paleocene of Bolivia (ed. Muizon, C. de) Mém. Mus. Natl Hist. Nat. Paris 165, 21–90 (1995).

  25. 25

    Luo, Z. & Crompton, A. W. Transformations of the quadrate (incus) through the transition from non-mammalian cynodonts to mammals. J. Vert. Paleontol. 14, 341–374 (1994).

  26. 26

    Rougier, G. W., Wible, J. R. & Hopson, J. A. Basicranial anatomy of Priacodon fruitaensis (Triconodontidae, Mammalia) from the Late Jurassic of Colorado, and a reappraisal of mammaliaform interrelationships. Am. Mus. Novit. 3183, 1–28 (1996).

  27. 27

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

  28. 28

    Zeller, U. Die Entwicklung und Morphologie des Schädels von Ornithorhynchus anatinus (Mammalia: Prototheria: Monotremata). Abh. Senckenb. Naturf. Gesel. 545, 1–188 (1989).

  29. 29

    Wible, J. R. Origin of Mammalia: the craniodental evidence reexamined. J. Vert. Paleontol. 11, 1–28 (1991).

  30. 30

    Luo, Z., Crompton, A. W. & Lucas, S. G. Evolutionary origins of the mammalian promontorium and cochlea. J. Vert. Paleontol. 15, 113–121 (1995).

  31. 31

    Graybeal, A., Rosowski, J., Ketten, D. R. & Crompton, A. W. Inner ear structure in Morganucodon, an early Jurassic mammal. Zool. J. Linn. Soc. 96, 107–117 (1989).

  32. 32

    Kielan-Jaworowska, Z., Presley, R. & Poplin, C. The cranial vascular system in taeniolabidoid multituberculate mammals. Phil. Trans. R. Soc. Lond. B 313, 525–602 (1986).

  33. 33

    Luo, Z. & Ketten, D. R. CT scanning and computerized reconstructions of the inner ear structure of multituberculate mammals. J. Vert. Paleontol. 11, 220–228 (1991).

  34. 34

    Meng, J. & Wyss, A. Monotreme affinities and low-frequency hearing suggested by multituberculate ear. Nature 377, 141–144 (1995).

  35. 35

    Lillegraven, J. A. & Krusat, G. Cranio-mandibular anatomy of Haldanodon exspectatus (Docondontia; Mammalia) from the Late Jurassic of Portugal and its implications to the evolution of mammalian characters. Contrib. Geol. 28, 39–138 (1991).

  36. 36

    Meng, J. & Fox, R. C. Therian petrosals from the Oldman and Milk River Formations (Late Cretaceous), Alberta, Canada. J. Vert. Paleontol. 15, 122–130 (1995).

  37. 37

    Wible, J. R. & Hopson, J. A. in Mammal Phylogeny Vol. 1(eds Szalay, F. S., Novacek, M. J. & McKenna, M. C.) 45–62 (Springer, New York, (1993)).

  38. 38

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

  39. 39

    Jenkins, F. A. J The movement of the shoulder in claviculate and aclaviculate mammals. J. Morphol. 144, 71–84 (1974).

  40. 40

    Jenkins, F. A. J & Weijs, W. A. The functional anatomy of the shoulder in the Virginia opossum (Didelphis virginiana). J. Zool. 188, 379–410 (1979).

  41. 41

    Jenkins, F. A. J The functional anatomy and evolution of the mammalian humero-ulnar joint. Am. J. Anat. 137, 281–298 (1973).

  42. 42

    Gambaryan, P. P. & Kielan-Jaworowska, Z. Sprawling versus parasagittal stance in multituberculate mammals. Acta Palaeontol. Pol. 42, 13–44 (1997).

  43. 43

    Hopson, J. A. in Major Features of Vertebrate Evolution (eds Prothero, D. R. & Schoch, R. M.) 190–219 (Paleontological Society Short Courses, Knoxville, TN, (1994)).

  44. 44

    Kielan-Jaworowska, Z., Crompton, A. W. & Jenkins, F. A. J The origin of egg-lying mammals. Nature 326, 871–873 (1987).

  45. 45

    Crompton, A. W. in Early Mammals (eds Kermack, D. M. & Kermack, K. A.) 65–87 (Academic, London, (1971)).

  46. 46

    Crompton, A. W. & Jenkins, F. A. J in Mesozoic Mammals: the First Two-thirds of Mammalian History (eds Lillegraven, J. A., Kielan-Jaworowska, Z. & Clemens, W. A.) 59–72 (Univ. California Press, Berkeley, (1979)).

  47. 47

    Kemp, T. S. The relationships of mammals. Zool. J. Linn. Soc. 77, 353–384 (1983).

  48. 48

    Rowe, T. in Mammal Phylogeny Vol. 1(eds Szalay, F. S., Novacek, M. J. & McKenna, M. C.) 129–145 (Springer, New York, (1993)).

  49. 49

    Klima, M. Die Frühentwicklung des Schültergürtels und des Brustbeins bei den Monotremen (Mammalia: Prototheria). Adv. Anat. Embryol. Cell Biol. 47, 1–80 (1973).

  50. 50

    Klima, M. Early development of the shoulder girdle and sternum in marsupials (Mammalia: Metatheria). Adv. Anat. Embryol. Cell Biol. 109, 1–91 (1987).

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We thank K. C. Beard, M. Dawson, R. Fox, Z. Kielan-Jaworowska, B. Krebs, T.Martin, J. Meng, R. Presley, G. Rougier, P. Sereno, A. Sun and J. Wible for suggestions on the manuscript; L.-H. Hou for field assistance; G.-H. Cui for photography; and H. Zhang for preparation. Research was supported by National Natural Science Foundation of China (to C.L.), the Rea Postdoctoral Fellowship of Carnegie Museum (to Y. W.), National Science Foundation of USA, National Geographic Society, and the M.Graham Netting Fund of Carnegie Museum (to Z.L.).

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Correspondence to Zhexi Luo or Chuankui Li.

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Hu, Y., Wang, Y., Luo, Z. et al. A new symmetrodont mammal from China and its implications for mammalian evolution. Nature 390, 137–142 (1997) doi:10.1038/36505

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