Zalambdalestes

Zalambdalestes Temporal range: Late Cretaceous PreꞒ Ꞓ O S D C P T J K Pg N
Zalambdalestes lechei skull and lower jaw, Museum of Evolution Warsaw
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	incertae sedis
Family:	†Zalambdalestidae
Genus:	†Zalambdalestes Gregory & Simpson, 1926
Species
Z. lechei Gregory & Simpson, 1926 (type)

Zalambdalestes (meaning much-like-lambda robber) is an extinct genus of eutherian mammal known from the Upper Cretaceous in Mongolia.

Life restoration of Z. lechei

Description

Zalambdalestes was a hopping animal with a long snout, long teeth, a small brain and large eyes. It was about 20 centimetres (7.9 in) long, with a head only 5 centimetres (2 in) long. It had strong front paws and even stronger rear ones, sharing specializations to saltation similar to those of modern rabbits.[1][2] It was most likely not a placental due to the presence of an epipubic bone,[1][3] It had a unique axis that allowed for rapid movements, and in life it might have had spines or bristly fur.[4]

Biology

Its diet was probably composed mainly of insects that it hunted in the forest undergrowth using its sharp, interlocking teeth.[5] A well-preserved series of cervical vertebrae, including the axis, but not the atlas, seem to suggest vermivory.[4] Unlike modern placental mammals, Zalambdalestes had an epipubic bone, meaning it was probably restricted reproductively in the same way as modern monotremes and marsupials,[1] though a study on multituberculate reproduction suggests early eutherians could give birth to well-developed young.[6] Its unique axis allowed for rapid movements to catch prey.[4]

Life reconstruction of Z. lechei

References

• Parker, Steve. Dinosaurs: the complete guide to dinosaurs. Firefly Books Inc, 2003. Pg. 402

1. Rose, Kenneth D.; Archibald, J. David, eds. (2005). The Rise of Placental Mammals: Origins and Relationships of the Major Extant Clades. Johns Hopkins University Press. ISBN 9780801880223.
2. Chen, Meng; Wilson, Gregory P. (2015). "A multivariate approach to infer locomotor modes in Mesozoic mammals". Paleobiology. 41 (2): 280–312. Bibcode:2015Pbio...41..280C. doi:10.1017/pab.2014.14. S2CID 86087687.
3. Dykes, Kevin T. "Mesozoic Mammals; Zalambdalestidae, Lipotyphla?, Cimolestidae and Cretaceous Taeniodonta". Mesozoic Eucynodonts. Archived from the original on March 4, 2006.
4. Arnold, Patrick; Janiszewska, Katarzyna; Li, Qian; O'Connor, Jingmai K.; Fostowicz-Frelik, Łucja (April 16, 2024). "The Late Cretaceous eutherian Zalambdalestes reveals unique axis and complex evolution of the mammalian neck". Science Bulletin. 69 (11): 1767–1775. Bibcode:2024SciBu..69.1767A. doi:10.1016/j.scib.2024.04.027. PMID 38702276.
5. Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 201. ISBN 1-84028-152-9.
6. Urton, James (July 25, 2022). "New study challenges old views on what's 'primitive' in mammalian reproduction". UW News. University of Washington. Retrieved April 6, 2024.

Further reading

• Wible, John R.; Novacek, Michael J.; Rougier, Guillermo W. (2004). "New data on the skull and dentition in the Mongolian Late Cretaceous eutherian mammal Zalambdalestes" (PDF). Bulletin of the American Museum of Natural History. 281: 1–144. doi:10.1206/0003-0090(2004)281<0001:NDOTSA>2.0.CO;2. hdl:2246/449. S2CID 83491778.