Gobiconodontidae is afamily of extinctmammals that ranged from the mid-Jurassic to the earlyLate Cretaceous, though most common during theEarly Cretaceous.[6] The Gobiconodontids form a diverse lineage of carnivorous non-therian mammals, and include some of the best preserved Mesozoic mammal specimens.
Like many other non-therian mammals, gobiocontids retained classical mammalian synapomorphies likeepipubic bones (and likely the associated reproductive constrictions),venomous spurs and sprawling limbs. ThroughSpinolestes we also know that they hadfur similar to that of modern mammals, with compoundhair follicles with primary and secondary hairs.Spinolestes also possesses a cleardiaphragm like modern mammals, as well asspines, dermalscutes and an ossifiedMeckel's cartilage. Furthermore, it may also display signs ofdermatophytosis, suggesting that gobiconodontids, like modern mammals, were vulnerable to this type of fungal infection.[5]
Gobiconodontid dentition, being classically triconodont, has no analogue among living mammals, so comparisons are difficult. Likeamphilestids but unliketriconodontids,occlusion happens by the molars essentially interlocking, with lowercusp "a" basically fitting between two upper molars.[6] Nonetheless, it's clear that most if not all gobiconodontids were primarily carnivorous, given the presence of long, sharp canines and incisors,[note 1] premolars with trenchant main cusps that were well suited to grasp and pierce prey, strong development of the mandibular abductor musculature, bone crushing ability in at least some species and several other features.[7]
Gobiconodontids are often among the largest mammals in Mesozoic faunal assemblages, with forms likeRepenomamus andGobiconodon exceeding 2 kilos. They were among the first mammals to be specialised to hunt vertebrate prey, and likely occupied the highest trophic levels among mammals in their faunal communities. Several forms likeGobiconodon andRepenomamus show evidence of scavenging, being among the few Mesozoic mammals to have significantly exploited that.[7] Evidence of predation on significantly larger dinosaurs is also known.[8]
At least in carnivorous niches, gobiconodontids were probably replaced bydeltatheroideanmetatherians, which are the dominant carnivorous mammals inLate Cretaceous faunal assemblages.[9] Competition between both groups is unattested, but in Asia the Early Cretaceous gobiconodontid diversity is replaced entirely by a deltatheroidean one, while in North AmericaNanocuris appears after the absence ofGobiconodon and other larger eutriconodonts.[10]
At leastSpinolestes had xenarthrous vertebrae and osseous scutes, convergent to those of modernxenarthrans and to a lesser extent thehero shrew. This genus may have displayed an ecological role similar to that of modernanteaters,pangolins,echidnas,aardvark,aardwolf andnumbat, being the second known Mesozoic mammal afterFruitafossor to have done so.[11]
Uniquely among crown-group mammals, gobiconodontids replaced their molariform teeth by successors of similar complexity, while in other mammals less complex replacements are the norm.[12]
^Nao Kusuhashi; Yuan-Qing Wang; Chuan-Kui Li; Xun Jin (2019). "New gobiconodontid (Eutriconodonta, Mammalia) from the Lower Cretaceous Shahai and Fuxin formations, Liaoning, China".Vertebrata PalAsiatica. in press.doi:10.19615/j.cnki.1000-3118.190724.
^abJ.; Hu, Y.-M.; Wang, Y.-Q.; Li, C.-K. (2005). "A new triconodont (Mammalia) from the Early Cretaceous Yixian Formation of Liaoning, China".Vertebrata PalAsiatica.43 (1):1–10.
^abcZofia Kielan-Jaworowska; Richard L. Cifelli; Zhe-Xi Luo (2004). "Chapter 7: Eutriconodontans".Mammals from the Age of Dinosaurs: origins, evolution, and structure. New York: Columbia University Press. pp. 216–248.ISBN978-0-231-11918-4.
^Zofia Kielan-Jaworowska; Richard L. Cifelli; Zhe-Xi Luo (2004). "Chapter 12: Metaherians".Mammals from the Age of Dinosaurs: origins, evolution, and structure. New York: Columbia University Press. pp. 425–462.ISBN978-0-231-11918-4.
