a large sample of Thrinaxodon skulls, ranging between 30 and 96 mm in length. These dentition patterns are similar to that of Morganucodon, allowing one to make the assumption that these dentition patterns arose within Thrinaxodontidae and extended into the records of early Mammalia. Adult T. liorhinus assumes the dental pattern of the four incisors, one canine and six postcanines on each side of the upper jaw. This pattern is reflected in the lower jaw by a dental formula of three incisors, one canine and 7–8 postcanines on each side of the lower jaw. With this formula, one can make a small note that in general, adult Thrinaxodon contained anywhere between 44 and 46 total teeth. Upper incisors in T. liorhinus assume a backwards directed cusp, and they go from being curved and pointed at their most distal point, and become broader and rounder as they reach their proximal insertion point into the premaxilla. The fourth upper incisor greatly resembles the form of that of a small canine; however, it is positioned too far anteriorly to be a functional canine. Lower incisors possess a very broad base, which is progressively reduced, heading distally towards the tip of the tooth. The lingual face of the lower incisors are most often concave while the labial face is often convex, and these lower incisors are oriented anteriorly, except in some cases for the third lower incisor, which can assume a more dorsoventral orientation. The incisors are, for the most part, single functional teeth encompassing a broad, cone-like morphology. The canines of T. liorhinus possess small dorsoventrally directed facets on their surfaces, by our understanding, these facets are related to occlusion. Each canine possesses a replacement canine located within the jaw, posterior to the existing canine, neither of the replacement or functional canine teeth possess any serrated margins only the small facets. It is important to note that the lower canine is directed almost vertically (dorsoventrally) while the upper canine is directed slightly anteriorly. The upper and lower postcanines in T. liorhinus share some common features but also vary quite a fair amount in comparison to one another. The first postcanine (just posterior to the canine) is most often smaller than the other postcanines and is most often bicuspid. Including the first postcanine, if any of the other postcanines are bicuspid, then it is safe to assume that the posterior accessary cusp is present