Maizotemnus

The holotype of Maizotemnus is a relatively incomplete skull. It includes a partial right maxilla with several teeth, one of the left cheek teeth, and five fragments of the mandible. Some of these fragments are not included within the holotype, but the authors do not specify which exact bones are part of the holotype and which are referred.^[1]

Maizotemnus was a relatively small toxodont. Although the remains are incomplete, Fernández and colleagues constructed an estimate of the animal's full size using multiple methods based on closely-related taxa. They published two estimates of its size: 19.85 kg (43.8 lb) or 26.73 kg (58.9 lb). These were based on the size of the teeth based on close relatives. Other methods of estimation based on less closely-related taxa produced much wider estimates—between 8–71 kg (18–157 lb)—but the authors did not consider these results to be very likely. The fragmentary nature of the remains led the authors to regard all the estimates they published as tentative and precise estimates would be impossible until the discovery of more fossils of this taxon.^[1]

The diagnosis of Maizotemnus from its close relatives is based mostly on the anatomy of the molars. The molars are longer on the mesio-distal axis (from the front to back of the mouth) than those of its close relatives. They also have very low crowns relative to other primitive toxodonts. The molars are also more subtriangular in shape and are wider than they are long. The groove on the teeth is also more shallow than it is in other isotemnids. The degree of wear on the teeth suggest that the holotype individual was an adult when it died.^[1]

In their description of Maizotemnus, Fernández and colleagues conducted a phylogenetic analysis. Their analysis recovered affinities between Maizotemnus and "isotemnids", which are generally early-diverging toxodonts. However, their analysis failed to recover Isotemnidae as monophyletic. They did find a close relationship between Maizotemnus and the genera Anisotemnus and Pampatemnus, which were the primary taxa used to produce estimates of its body mass. An abbreviated version of the cladogram published by Fernández and colleagues is shown below.^[1]