Morphological variation and disparity in Lystrosaurus (Therapsida: Dicynodontia)

The dicynodont genus Lystrosaurus, a relative of the Kannemeyerids, is one of few terrestrial vertebrate genera which can be found on both sides of the Permian-Triassic (P-T) boundary (Botha and Smith, 2006); indeed, a single species, Lystrosaurus curvatus, is known from both periods. In the Permian, Lystrosaurus was of average abundance relative to other genera. Shortly following the P-T extinction, it drastically increased in abundance until it dominated the faunas it was present in (Botha and Smith, 2006). To date, Lystrosaurus fossils have been found in South Africa, India, Antarctica, China, and Russia (Grine et al., 2006). Abundance, survivorship, and expansive geographic presence give Lystrosaurus extreme potential as a model organism for multiple questions involving ideas such as extinction survivorship, biogeography, and ecology; however, Lystrosaurus has been subject to the practice of an extreme version of "splitter" taxonomy in the past. Here I quantify Lystrosaurus morphology using geometric morphometrics. Chinese Lystrosaurus taxonomy has not been analyzed in light of this. My results show that they are different from Gondwanan Lystrosaurus and represent at least one if not two unique species.