Dromatheriidae is an extinctfamily of prozostrodontiancynodonts, closely related to mammals. Members of the family are known from the Late Triassic (Carnian to Rhaetian) of India,[1]Europe and North America. Apart from a few jaw fragments, dromatheriids are mainly known from their sectorial (flesh-slicing) postcanine teeth. The teeth were fairly typical among early prozostrodontians, as they were labiolingually compressed (flattened sideways), with a single root and crown hosting a longitudinal row of sharp cusps. Dromatheriids in particular have a very narrow and symmetrical crown (when seen from above) without a prominent cingulum (a ridge or array of cuspules adjacent to the main cusps).[1][2][3]
Dromatheriid teeth on average have four main cusps, though some have as few as two (Dromatherium) or three (Tricuspes), or as many as six (Inditherium, Pseudotriconodon). Although the teeth have a single root, a vertical furrow on each side of the root appears to be a trait incipient towards the two fully divided roots of mammaliaforms.[1][3] Making note of this condition, some authors have suggested that dromatheriids are a paraphyletic group ancestral to mammaliaforms.[2] Other studies instead consider the closest relatives of dromatheriids to be the "therioherpetids" Therioherpeton and Meurthodon, which may even be placed within the family.[3] However, the broader cusps of Therioherpeton and the divided root of Meurthodon dissuade their position within Dromatheriidae.[4]
References
^ abcBhat, Mohd Shafi; Ray, Sanghamitra; Datta, P. M. (2020). "New cynodonts (Therapsida, Eucynodontia) from the Late Triassic of India and their significances". Journal of Paleontology. 95 (2): 376–393. doi:10.1017/jpa.2020.95. S2CID228836405.
