Ausktribosphenidae

Ausktribosphenidae is a family of mammals from the Early Cretaceous of Australia that are closely related to monotremes.

Ausktribosphenidae
Temporal range: Early Cretaceous
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Australosphenida
Family: †Ausktribosphenidae
Rich et al., 1997[1]
Genera

Classification and taxonomy

Ausktribosphenidae is closely related to monotremes and hence the two form the yinotherian clade Australosphenida. It includes two species, Ausktribosphenos nyktos and Bishops whitmorei, both of which are known only from skull and jaw fragments.[3]

Morphology

Like other Australosphenida, ausktribosphenids have tribosphenic molars.

Distribution

Given that Ausktribosphenidae has been found in Early Cretaceous deposits in Australia, its occurrence has ramifications for knowledge of early monotreme paleobiogeography because Australia was connected only to Antarctica, and placentals originated in the northern hemisphere and were confined to it until continental drift formed land connections from North America to South America, from Asia to Africa and from Asia to India. The late Cretaceous map[4] shows how the southern continents are separated. However, the cladistic analysis of Cifelliodon recovers Fruitafossor as a monotreme relative, suggesting that yinotherians may have originated in the Northern Hemisphere.[5]

References
  1. Rich, Thomas H.; Vickers-Rich, Patricia; Constantine, Andrew; Flannery, Timothy F.; Kool, Lesley; van Klaveren, Nicholas (1997). "A Tribosphenic Mammal from the Mesozoic of Australia". Science. 278 (5342): 1438–1442. doi:10.1126/science.278.5342.1438. JSTOR 2894756.
  2. Thomas H. Rich; Peter Trusler; Lesley Kool; David Pickering; Alistair Evans; Karen Siu; Anton Maksimenko; Martin Kundrat; Neil J. Gostling; Steven Morton; Patricia Vickers-Rich (2020). "A third, remarkably small, tribosphenic mammal from the Mesozoic of Australia". In Guntupalli V.R. Prasad; Rajeev Patnaik (eds.). Biological consequences of plate tectonics. New perspectives on post-Gondwana break-up–A tribute to Ashok Sahni. Vertebrate Paleobiology and Paleoanthropology. Springer. pp. 67–75. doi:10.1007/978-3-030-49753-8_3. ISBN 978-3-030-49752-1.
  3. "Mammalia - Palaeos". Archived from the original on 2007-04-12.
  4. Christopher R. Scotese. "New Oceans Begin to Open". Paleomap project. Retrieved 20 September 2010.
  5. Adam K. Huttenlocker; David M. Grossnickle; James I. Kirkland; Julia A. Schultz; Zhe-Xi Luo (2018). "Late-surviving stem mammal links the lowermost Cretaceous of North America and Gondwana". Nature. in press. doi:10.1038/s41586-018-0126-y.


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