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Highly specialized mammalian skulls from the Late Cretaceous of South America


Dryolestoids are an extinct mammalian group belonging to the lineage leading to modern marsupials and placentals1,2. Dryolestoids are known by teeth and jaws from the Jurassic period of North America and Europe2,3, but they thrived in South America up to the end of the Mesozoic era and survived to the beginnings of the Cenozoic2,4,5,6,7. Isolated teeth and jaws from the latest Cretaceous of South America provide mounting evidence that, at least in western Gondwana, dryolestoids developed into strongly endemic groups by the Late Cretaceous4,5,6,7,8,9. However, the lack of pre-Late Cretaceous dryolestoid remains made study of their origin and early diversification intractable. Here we describe the first mammalian remains from the early Late Cretaceous of South America, including two partial skulls and jaws of a derived dryolestoid showing dental and cranial features unknown among any other group of Mesozoic mammals, such as single-rooted molars preceded by double-rooted premolars, combined with a very long muzzle, exceedingly long canines and evidence of highly specialized masticatory musculature. On one hand, the new mammal shares derived features of dryolestoids1,2,3 with forms from the Jurassic of Laurasia, whereas on the other hand, it is very specialized and highlights the endemic, diverse dryolestoid fauna from the Cretaceous of South America. Our specimens include only the second mammalian skull known for the Cretaceous of Gondwana, bridging a previous 60-million-year gap in the fossil record, and document the whole cranial morphology of a dryolestoid, revealing an unsuspected morphological and ecological diversity for non-tribosphenic mammals.

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Figure 1: Cronopio dentiacutus MPCA 454 type skull and MPCA 453 right lower jaw.
Figure 2: Cronopio dentiacutus MPCA 454 type skull and MPCA 453 skull and right lower jaw.
Figure 3: Cronopio dentiacutus MPCA 454 holotype (upper teeth).
Figure 4: Reconstruction of the skull and jaws of Cronopio dentiacutus based on MPCA 453 and 454.
Figure 5: Simplified phylogenetic tree of the major taxa included in the analysis.


  1. Prothero, D. R. New Jurassic mammals from Como Bluff, Wyoming, and the interrelationships of non-tribosphenic Theria. Bull. Am. Mus. Nat. Hist. 167, 281–317 (1981)

    Google Scholar 

  2. Kielan-Jaworowska, Z., Cifelli, R. L. & Luo, Z. X. Mammals from the Age of Dinosaurs. Origins, Evolution, and Structure (Columbia Univ. Press, 2004)

    Book  Google Scholar 

  3. Martin, T. Dryolestidae (Dryolestoidea, Mammalia) aus dem Oberen Jura von Portugal. Abh. Senckenb. Naturforsch. Ges. 550, 1–119 (1999)

    Google Scholar 

  4. Bonaparte, J. F. Sobre Mesungulatum housayi y nuevos mamíferos cretácicos de Patagonia, Argentina. Actas Congr. Argent. Paleontol. Estratigr. 2, 63–95 (1986)

    Google Scholar 

  5. Bonaparte, J. F. New Late Cretaceous mammals from the Los Alamitos Formation, southern Patagonia. Natl Geogr. Res. 6, 63–93 (1990)

    Google Scholar 

  6. Bonaparte, J. F. Approach to the significance of the Late Cretaceous mammals of South America. Berliner Geowiss. 13, 30–44 (1994)

    Google Scholar 

  7. Gelfo, J. N. & Pascual, R. Peligrotherium tropicalis (Mammalia, Dryolestida) from the early Paleocene of Patagonia, a survival from a Mesozoic Gondwanan radiation. Geodiversitas 23, 69–379 (2001)

    Google Scholar 

  8. Rougier, G. W., Forasiepi, A. M., Hill, R. V. & Novacek, M. J. New mammalian remains from the Late Cretaceous La Colonia Formation, Patagonia, Argentina. Acta Palaeontol. Pol. 54, 195–212 (2009)

    Article  Google Scholar 

  9. Chornogubsky, L. New remains of the dryolestoid mammal Leonardus cuspidatus from the Los Alamitos Formation (Late Cretaceous, Argentina). Paläont. Z. 85, 1–8 (2011)

    Article  Google Scholar 

  10. Leanza, H. A., Apesteguía, S., Novas, F. E. & de la Fuente, M. S. Cretaceous terrestrial beds from the Neuquén Basin (Argentina) and their tetrapod assemblages. Cretac. Res. 25, 61–87 (2004)

    Article  Google Scholar 

  11. Apesteguía, S. & Novas, F. E. Large Cretaceous sphenodontian from Patagonia provides insight into lepidosaur evolution in Gondwana. Nature 425, 609–612 (2003)

    ADS  Article  Google Scholar 

  12. Apesteguía, S. & Zaher, H. A. Cretaceous terrestrial snake with robust hindlimbs and a sacrum. Nature 440, 1037–1040 (2006)

    ADS  Article  Google Scholar 

  13. Gallina, P. A. & Apesteguía, S. Cathartesaura anaerobica gen. et sp. nov., a new rebbachisaurid (Dinosauria, Sauroppoda) from the Huincul Formation (Upper Cretaceous), Río Negro, Argentina. Rev. Mus. Argent. Cienc. Nat. 7, 153–166 (2005)

    Article  Google Scholar 

  14. Makovicky, P., Apesteguía, S. & Agnolín, F. L. The earliest dromaeosaurid theropod from South America. Nature 437, 1007–1011 (2005)

    ADS  CAS  Article  Google Scholar 

  15. Páez Arango, N. Dental and Craniomandibular Anatomy of Peligrotherium tropicalis: the Evolutionary Radiation of South American Dryolestoid Mammals. Thesis, Univ. Louisville. (2008)

    Google Scholar 

  16. Krebs, B. Drescheratherium acutum gen. et sp. nov., ein neuer Eupantotherier (Mammalia) aus dem Oberen Jura von Portugal. Berliner Geowiss. 28, 91–111 (1998)

    Google Scholar 

  17. Bonaparte, J. F. & Migale, L. A. Protomamíferos y mamíferos Mesozoicos de América del Sur (Museo de Ciencias Naturales Carlos Ameghino, 2010)

    Google Scholar 

  18. Bonaparte, J. F. Una nueva especie de Triconodonta (Mammalia) de la Formación Los Alamitos, Provincia de Río Negro y comentarios sobre su fauna de mamíferos. Ameghiniana 29, 99–110 (1992)

    Google Scholar 

  19. Rougier, G. W. & Wible, J. R. In Amniote Paleobiology: Phylogenetic and Functional Perspectives on the Evolution of Mammals, Birds and Reptiles (eds Carrano, M. T., Gaudin, T. J., Blob, R. & Wible, J. R. ) 269–311 (Univ. Chicago Press, 2006)

    Google Scholar 

  20. Turnbull, W. D. Mammalian masticatory apparatus. Fieldiana Geol. 18, 153–356 (1970)

    Google Scholar 

  21. Meng, J., Wang, Y. & Li, C. Transitional mammalian middle ear from a new Cretaceous Jehol eutriconodont. Nature 472, 181–185 (2011)

    ADS  CAS  Article  Google Scholar 

  22. Wible, J. R., Rougier, G. W., Novacek, M. J. & Asher, R. J. The eutherian mammal Maelestes gobiensis from the Late Cretaceous of Mongolia and the phylogeny of Cretaceous eutherians. Bull. Am. Mus. Nat. Hist. 327, 1–123 (2009)

    Article  Google Scholar 

  23. Rougier, G. W. et al. In Dinosaurios y Paleontología desde América Latina (eds Calvo, J., Porfiri, J., González Riga, B. & Dos Santos, D. ) 195–214 (Editorial de la Universidad Nacional de Cuyo, 2011)

    Google Scholar 

  24. 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 

  25. Rowe, T. B., Rich, T. H., Vickers-Rich, P., Springer, M. & Woodburne, M. O. The oldest platypus and its bearing on divergence timing of the platypus and echidna clades. Proc. Natl Acad. Sci. USA 105, 1238–1242 (2008)

    ADS  CAS  Article  Google Scholar 

  26. Sigogneau-Russell, D. Further data and reflexions on the tribosphenid mammals (Tribotheria) from the Early Cretaceous of Morocco. Bull. Mus. Natl Hist. Nat. Paris 16, 291–312 (1995)

    Google Scholar 

  27. Wilson, G. P., Das Sarma, D. C. & Anantharaman, S. Late Cretaceous sudamericid gondwanatherian mammals from India with paleobiogeographic considerations of Gondwanan mammals. J. Vertebr. Paleontol. 27, 521–531 (2007)

    Article  Google Scholar 

  28. Gurovich, Y. & Beck, R. The phylogenetic position of the enigmatic mammalian clade Gondwanatheria. J. Mamm. Evol. 16, 25–49 (2009)

    Article  Google Scholar 

  29. Sigogneau-Russell, D. & Ensom, P. C. Thereuodon (Theria, Symmetrodonta) from the Lower Cretaceous of North Africa and Europe, and a brief review of symmetrodonts. Cretac. Res. 19, 445–470 (1998)

    Article  Google Scholar 

  30. 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)

    Google Scholar 

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We thank M. Salinas, P. A. Gallina and P. J. Makovicky for finding the best specimens; the Avelás and Pincheira families for logistical support; C. Muñoz and R. Barbieri from the MPCA for access to collections under their care; J. A. González and A. Davidson for illustration and technical assistance. Field work permits and loans were facilitated by M. Solorza. C. Corbitt and J. R. Wible read an earlier version of the manuscript. Field work and research was supported by the Antorchas Foundation, American Museum of Natural History and NSF grants DEB 0946430, DEB 1068089 and ATOL 0629959 (to G.W.R.), The Jurassic Foundation (to S.A.) and NASA and Field Museum Womens’ Board (to P. J. Makovicky). This is L.C.G.’s R-46 contribution to the IDEAN.

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G.W.R. wrote the manuscript with contributions from all authors, edited the figures, scored the matrix and performed the phylogenetic analysis; S.A. edited the manuscript and figures; L.C.G. edited the manuscript, figures, matrix and performed the phylogenetic analysis.

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Correspondence to Guillermo W. Rougier.

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The authors declare no competing financial interests.

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Rougier, G., Apesteguía, S. & Gaetano, L. Highly specialized mammalian skulls from the Late Cretaceous of South America. Nature 479, 98–102 (2011).

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