Gobiconodontidae

Gobiconodontids Temporal range: Early Cretaceous PreЄ Є O S D C P T J K Pg N
Life restoration of Gobiconodon
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Synapsida
Class:	Mammalia
Order:	†Gobiconodonta
Family:	†Gobiconodontidae Jenkins Jr. & Schaff, 1988
Genera
Gobiconodon Trofimov, 1978 Hangjinia Godefroit & Guo, 1999 Huasteconodon Montellano et al., 2008 Meemannodon Meng et al., 2005 Repenomamus Li et al., 2000 Spinolestes Thomas Martin, Jesús Marugán-Lobón, Romain Vullo, Hugo Martín-Abad, Zhe-Xi Luo and Angela D. Buscalioni (2015). "A Cretaceous eutriconodont and integument evolution in early mammals". Nature 526 (7573): 380–384. doi:10.1038/nature14905.

The Gobiconodontidae are a group of extinct mammals from the Early Cretaceous. They are a diverse lineage of carnivorous non-therian mammals, and include some of the best preserve Mesozoic mammal specimens.

Biology

Like many other non-therian mammals, gobiocontids retained classical mammalian synapomorphies like epipubic bones (and likely the associated reproductive constrictions), venomous spurs and sprawling limbs. Through Spinolestes we also know that they had fur similar to that of modern mammals, with compound hair follicles with primary and secondary hairs. Spinolestes also possesses a clear diaphragm like modern mammals, as well as spines, dermal scutes and an ossified Meckel's cartilage. Furthermore, it may also display signs of dermatophytosis, suggesting that gobiconodontids, like modern mammals, were vulnerable to this type of fungal infection.

Gobiconodontid dentition, being classically triconodont, has no analogue among living mammals, so comparisons are difficult. However, its clear that most if not all gobiconodontids were primarily carnivorous, given the presence of long, sharp canines, premolars with trenchant main cusps that were well suited to grasp and pierce prey, strong development of the madibular abductor musculature, bone crushing ability in at least some species and several other features.

Gobiconodontids are often among the largest mammals in Mesozoic faunal assemblages, with forms like Repenomamus and Gobiconodon exceeding 2 kilos. They were among the first mammals to be specialised for vertebrate prey, and likely occupied the highest trophic lvels among mammals in their faunal communities. Several forms like Gobiconodon and Repenomamus show evidence of scavenging, being among the few Mesozoic mammals to have significantly exploited that.

At least in carnivorous niches, gobiconodontids were probably replaced by deltatheroidean metatherians, which are the dominant carnivorous mammals in Late Cretaceous faunal assemblages.

At least Spinolestes had xenarthrous vertebrae and osseous scutes, convergent to those of modern xenarthrans and to a lesser extent the hero shrew. This genus may have displayed an ecological role similar to that of modern anteaters, pangolins, echidnas, aardvark, aardwolf and numbat, being the second known Mesozoic mammal after Fruitafossor to have done so.

Phylogeny

Cladogram after Marisol Montellano, James A. Hopson, James M. Clark (2008) and Gao et al. (2010).

Gobiconodontidae	Hangjinia ? Meemannodon Repenomamus Gobiconodon (incl. Guchinodon) Huasteconodon

References

• Thomas S. Kemp: The Origin & Evolution of Mammals. Oxford University Press, Oxford 2005, 331 Seiten, ISBN 0-19-850761-5.