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Dromatheriidae
Dromatheriidae is an extinct family of prozostrodontian cynodonts, closely related to mammals. Members of the family are known from the Late Triassic (Carnian to Rhaetian) of India, 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). 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 trai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prozostrodontia
Prozostrodontia is a clade of cynodonts including mammaliaforms and their closest relatives such as Tritheledontidae and Tritylodontidae. It was erected as a node-based taxon by Liu and Olsen (2010) and defined as the least inclusive clade containing ''Prozostrodon brasiliensis'', '' Tritylodon langaevus'', '' Pachygenelus monus'', and ''Mus musculus'' (the house mouse). Prozostrodontia is diagnosed by several characters, including: * Reduced prefrontal and postorbital bones, with a reduction or disappearance of a strut of bone called the postorbital bar separating the eye socket from the temporal region * Unconnected dentary bones in the lower jaw * The presence of a small hole in the skull called the sphenopalatine foramen * A sagittal crest extending along the top of the skull and connecting with a lambdoidal crest at the back of the skull * Neural spines of the dorsal vertebrae angled backward * A convex-shaped iliac crest and a reduced posterior iliac spine on the hip * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |