Zhelestidae

Zhelestidae is a lineage of extinct eutherian mammals. Occurring in the Late Cretaceous from the Turonian to the Maastrichtian, they were an extremely successful group, with representatives present in Europe, Asia, India (and subsequently in Madagascar), Africa and North America, ostensibly rendering them a cosmopolitan clade. They were specialised towards an herbivorous lifestyle and were in fact initially considered stem-ungulates,[1] but the presence of epipubics and "archaic" dental characters render them as non-placental eutherians.[2][3][4][5][6]

Zhelestidae Temporal range: Late Cretaceous PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Clade:	Eutheria
Family:	†Zhelestidae Nessov (1985)
Genera
?Alostera Aspanlestes Avitotherium Borisodon Eoungulatum Eozhelestes Gallolestes ?Khuduklestes ?Mistralestes ?Oxlestes ?Paranyctoides Parazhelestes Sheikhdzheilia Sorlestes Zhalmousia Zhelestes Lainodontinae Labes Lainodon ?Valentinella

Range

The earliest zhelestid remains occur in the Cenomanian of Central Asia. By the Campanian, however, they are present in Europe and North America, and by the Maastrichtian in India and in Madagascar (UA 8699). In Europe, then an island continent, taxa usually accepted to be zhelestids are the most common Late Cretaceous mammal remains, aside from Hateg Island where kogaionid multituberculates are more common instead, though there is a single possible zhelestid tooth there as well.[7]

Ecology

Zhelestids are well specialised towards an herbivorous diet, their teeth suited for a lateral chewing mechanism similar to that of modern ungulates. An exception to this might be forms like Oxlestes and Khuduklestes, which are normally interpreted as carnivorous, and perhaps a few forms like Borisodon which may have been insectivorous. Ranging from mouse sized forms to ones comparable to small ungulates in size, zhelestids occupied a massive variety of ecological guilds.

In contrast to their dietary divergence, the few available limb remains suggest that they weren't very specialised locomotion wise, in contrast to some other basal eutherians like for instance Zalambdalestes, which was long-limbed and had several adaptations for cursoriality and hopping.

There is evidence that zhelestids were in direct competition with another clade of Mesozoic herbivorous mammals, the multituberculates, being rarer in places where these were most common and vice versa.[8] However, multituberculates eventually outlived zhelestids, surviving the KT-mass extinctions everywhere but Asia, where the niches taken by both clades in the Cretaceous would be taken by early rodents.[9]

References

1. L. A. Nessov, J. D. Archibald, and Z. Kielan-Jaworowska. 1998. Ungulate-like mammals from the Late Cretaceous of Uzbekistan and a phylogenetic analysis of Ungulatomorpha. Bulletin of Carnegie Museum of Natural History 34:40-88
2. J. R. Wible, G. W. Rougier, M. J. Novacek and R. J. Asher. 2007. Cretaceous eutherians and Laurasian origin for placental mammals near the K/T boundary. Nature 447:1003-1006
3. J. DAVID ARCHIBALD and ALEXANDER AVERIANOV, Phylogenetic analysis, taxonomic revision, and dental ontogeny of the Cretaceous Zhelestidae (Mammalia: Eutheria), Version of Record online: 25 JAN 2012 DOI: 10.1111/j.1096-3642.2011.00771.x
4. Kenneth D. Rose, J. David Archibald, The Rise of Placental Mammals: Origins and Relationships of the Major Extant Clades, JHU Press, 22/02/2005
5. Rodolphe Tabuce, Thierry Tortosa, Monique Vianey-Liaud, Géraldine Garcia, Renaud Lebrun, Pascal Godefroit, Yves Dutour, Sévérine Berton, Xavier Valentin and Gilles Cheylan (2013). «New eutherian mammals from the Late Cretaceous of Aix-en-Provence Basin, south-eastern France». Zoological Journal of the Linnean Society 169 (3): 653-672. doi:10.1111/zoj.12074.
6. Averianov, A.O. and Archibald, J.D. 2013. New material and reinterpretation of the Late Cretaceous eutherian mammal Paranyctoides from Uzbekistan. Acta Palaeontologica Polonica 58 (1): 17–23. https://dx.doi.org/10.4202/app.2011.0131
7. Rodolphe Tabuce Thierry Tortosa Monique Vianey‐Liaud Géraldine Garcia Renaud Lebrun Pascal Godefroit Yves Dutour Sévérine Berton Xavier Valentin Gilles Cheylan, New eutherian mammals from the Late Cretaceous of Aix‐en‐Provence Basin, south‐eastern France, 29 October 2013 https://doi.org/10.1111/zoj.12074
8. Guillermo W. Rougier; Amir S. Sheth; Barton K. Spurlin; Minjin Bolortsetseg; Michael J. Novacek (2016). "Craniodental anatomy of a new Late Cretaceous multituberculate mammal from Udan Sayr, Mongolia" (PDF). Palaeontologia Polonica. 67: 197–248. doi:10.4202/pp.2016.67_197.
9. Wood, D. Joseph (2010). The Extinction of the Multituberculates Outside North America: a Global Approach to Testing the Competition Model (M.S.). The Ohio State University.