Marsupials, placentals and their close therian relatives possess complex (tribosphenic) molars that are capable of versatile occlusal functions. This functional complex is widely thought to be a key to the early diversification and evolutionary success of extant therians and their close relatives (tribosphenidans). Long thought to have arisen on northern continents, tribosphenic mammals have recently been reported from southern landmasses. The great age and advanced morphology of these new mammals has led to the alternative suggestion of a Gondwanan origin for the group. Implicit in both biogeographic hypotheses is the assumption that tribosphenic molars evolved only once in mammalian evolutionary history. Phylogenetic and morphometric analyses including these newly discovered taxa suggest a different interpretation: that mammals with tribosphenic molars are not monophyletic. Tribosphenic molars evolved independently in two ancient (holotherian) mammalian groups with different geographic distributions during the Jurassic/Early Cretaceous: an australosphenidan clade endemic to Gondwanan landmasses, survived by extant monotremes; and a boreosphenidan clade of Laurasian continents, including extant marsupials, placentals and their relatives.
This is a preview of subscription content, access via your institution
Open Access articles citing this article.
Multiple evolutionary origins and losses of tooth complexity in squamates
Nature Communications Open Access 14 October 2021
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Rent or buy this article
Get just this article for as long as you need it
Prices may be subject to local taxes which are calculated during checkout
McKenna, M. C. in Phylogeny of the Primates (eds Luckett, W. P. & Szalay, F. S.) 21–46 (Plenum, New York, 1975).
Hopson, J. A. in Major Features of Vertebrate Evolution (ed. Spencer, R. S.) 190 –219 (The Paleontological Society, Knoxville, 1994).
Patterson, B. Early Cretaceous mammals and the evolution of mammalian molar teeth. Fieldiana 13, 1–105 ( 1956).
Crompton, A. W. in Early Mammals (eds Kermack, D. M. & Kermack, K. A.) 65–87 (Zool. J. Linn. Soc., London, 1971).
Lillegraven, J. A. Biogeographical considerations of the marsupial-placental dichotomy. Annu. Rev. Ecol. Syst. 5, 263–283 (1974).
Flynn, J. J., Parrish, J. M., Rakotosamimanana, B., Simpson, W. F. & Wyss, A. E. A Middle Jurassic mammal from Madagascar. Nature 401, 57–60 (1999).
Rich, T. H. et al. A tribosphenic mammal from the Mesozoic of Australia. Science 278, 1438–1442 ( 1997).
Rich, T. H. et al. Early Cretaceous mammals from Flat Rocks, Victoria, Australia. Rec. Queen Vict. Mus. 106, 1– 35 (1999).
Kielan-Jaworowska, Z., Cifelli, R. L. & Luo, Z. Alleged Cretaceous placental from down under. Lethaia 31, 267–268 ( 1998).
Kielan-Jaworowska, Z. & Dashzeveg, D. D. Eutherian mammals from the Early Cretaceous of Mongolia. Zool. Scripta 18, 347–355 (1989).
Cifelli, R. L. Tribosphenic mammal from the North American Early Cretaceous. Nature 401, 363–366 ( 1999).
Rougier, G. W., Wible, J. R. & Novacek, M. J. Implications of Deltatheridium specimens for early marsupial history. Nature 396, 459 –463 (1998).
Archer, M., Flannery, T. F., Ritchie, A. & Molnar, R. First Mesozoic mammal from Australia—an Early Cretaceous monotreme. Nature 318, 363–366 (1985).
Archer, M., Murray, P., Hand, S. J. & Godthelp, H. in Mammal Phylogeny (eds Szalay, F. S., Novacek, M. J. & McKenna, M. C.) (Springer, New York, 1993).
Musser, A. M. & Archer, M. New information about the skull and dentary of the Miocene platypus Obdurodon dicksoni, and a discussion of ornithorhynchid relationships. Phil. Trans. R. Soc. Lond. B 353, 1063–1079 ( 1998).
Prothero, D. R. New Jurassic mammals from Como Bluff, Wyoming, and the interrelationships of non-tribosphenic Theria. Bull. Am. Mus. Nat. Hist. 167, 277–326 (1981).
Clemens, W. A. Jr & Mills, J. R. E. Review of Peramus tenuirostris. Bull. Br. Mus. Nat. Hist. 20, 89–113 ( 1971).
Krebs, B. Das Skelett von Henkelotherium guimarotae gen. et sp. nov. (Eupantotheria, Mammalia) aus dem Oberen Jura von Portugal. Berliner Geowiss. Abh. 133, 1–121 ( 1991).
Chow, M. & Rich, T. H. Shuotherium dongi, n. gen. and sp., a therian with pseudo-tribosphenic molars from the Jurassic of Sichuan, China. Aust. Mammal. 5, 127– 142 (1982).
Wang, Y.-Q., Clemens, W. A., Hu, Y.-M. & Li, C.-K. A probable pseudo-tribosphenic upper molar from the Late Jurassic of China and the early radiation of the Holotheria. J. Vert. Paleontol. 18, 777–787 ( 1998).
Sigogneau-Russell, D. Discovery of a Late Jurassic Chinese mammal in the upper Bathonian of England. C. R. Acad. Sci. 327, 571– 576 (1998).
Kielan-Jaworowska, Z., Crompton, A. W. & Jenkins, F. A. Jr The origin of egg-laying mammals. Nature 326, 871–873 (1987).
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, 1–38 (1996).
Wible, J. R., Rougier, G. W., Novacek, M. J., McKenna, M. C. & Dashzeveg, D. D. A mammalian petrosal from the Early Cretaceous of Mongolia: implications for the evolution of the ear region and mammaliamorph relationships. Am. Mus. Novit. 3149 , 1–19 (1995).
Rowe, T. B. Definition, diagnosis, and origin of Mammalia. J. Vert. Paleontol. 8, 241–264 ( 1988).
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).
Ji, Q., Luo, Z.-X. & Ji, S.-A. A Chinese triconodont mammal and mosaic evolution of the mammalian skeleton. Nature 398, 326– 330 (1999).
Archer, M. et al. The evolutionary history and diversity of Australian mammals. Aust. Mammal. 21, 1–45 (1999).
Griffiths, M. The Biology of the Monotremes (Academic, New York, 1978).
Zeller, U. Die Entwicklung und Morphologie des Schädels von Ornithorhynchus anatinus (Mammalia: Prototheria: Monotremata). Abh. der Senckenb. Naturfor. Gesel. 545, 1–188 ( 1989).
Killian, J. K. et al. M6P/IGF2R imprinting evolution in mammals. Mol. Cell 5, 707–716 ( 2000).
Penny, D. & Hasegawa, M. The platypus put in its place. Nature 387, 549–550 (1997).
Janke, A., Xu, X., & Anason, U. The complete mitochondrial genome of wallaroo (Macropus robustus) and the phylogenetic relationship among Monotremata, Marsupialia, and Eutheria. Proc. Natl Acad. Sci. USA 94, 1276– 1281 (1997).
Jacobs, L. L., Winkler, D. A. & Murry, P. A. Modern mammal origins: evolutionary grades in the Early Cretaceous of North America. Proc. Natl Acad. Sci. USA 86, 4992–4995 (1989).
Butler, P. M. The teeth of the Jurassic mammals. Proc. Zool. Soc. Lond. 109, 329–356 (1939).
Sigogneau-Russell, D. & Ensom, P. C. Découverte, dans le groupe de Purbeck (Berriasian, Angleterre), de plus ancien témoinage de l'existence de mammifères tribosphéniques. C. R. Acad. Sci. 319, 833–838 (1994).
Sigogneau-Russell, D. Découverte du premier mammifère tribosphénique du Mésozoı ¨que africain. C. R. Acad. Sci. 313, 1635–1640 (1991).
Cifelli, R. L. & de Muizon, C. Dentition and jaw of Kokopellia juddi, a primitive marsupial or near marsupial from the medial Cretaceous of Utah. J. Mammal. Evol. 4, 241–258 (1997).
Pascual, R. et al. First discovery of monotremes in South America. Nature 356, 704–705 ( 1992).
Bonaparte, J. F. New Late Cretaceous mammals from the Los Alamitos Formation, northern Patagonia. Nat. Geogr. Res. 6, 63– 93 (1990).
Pascual, R., Goin, F. J., González, P., Ardolino, A. & Puerta, P. A highly derived docodont from the Patagonian Late Cretaceous: evolutionary implications for Gondwanan mammals. Geodiversitas 22, 395– 414 (2000).
de Muizon, C., Cifelli, R. L. & Céspedes, R. The origin of dog-like marsupials and the early evolution of Gondwanian marsupials. Nature 389 , 486–489 (1997).
McKenna, M. C. & Bell, S. K. Classification of Mammals Above the Species Level (Columbia Univ. Press, New York, 1997).
Butler, P. M. Early trends in the evolution of tribosphenic molars. Biol. Rev. 65, 529–552 ( 1990).
We thank T. H. Rich, P. Vickers-Rich and M. Archer for providing comparative casts; and K. C. Beard, A. W. Crompton, M. R. Dawson, J. J. Flynn, J. J. Hurum, M. C. McKenna, M. J. Novacek, R. Presley, T. H. Rich, D. Sigogneau-Russell, J. R. Wible and A. R. Wyss for relevant discussion, and M. Klingler for assistance in illustration. Research was supported by National Science Foundation (USA) and National Geographic Society (Z.-X. L. and R.L.C), Carnegie Museum (Z.-X.L.) and Institute of Paleobiology, PAN (Z.K.-J.).
Rights and permissions
About this article
Cite this article
Luo, ZX., Cifelli, R. & Kielan-Jaworowska, Z. Dual origin of tribosphenic mammals. Nature 409, 53–57 (2001). https://doi.org/10.1038/35051023
This article is cited by
An African Radiation of ‘Dryolestoidea’ (Donodontidae, Cladotheria) and its Significance for Mammalian Evolution
Journal of Mammalian Evolution (2022)
Multiple evolutionary origins and losses of tooth complexity in squamates
Nature Communications (2021)
Rolling of the jaw is essential for mammalian chewing and tribosphenic molar function
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.