Anatomy of the holotype of 'Probelesodon' kitchingi revisited, a chiniquodontid cynodont (Synapsida, Probainognathia) from the early Late Triassic of southern Brazil

Abstract

Chiniquodontidae is a family of nonmammaliaform probainognathian cynodonts with occurrences in the Middle to Late Triassic of Africa and South America (Brazil and Argentina). The history of the family is marked by changes in composition and revisions due to the poor preservation of the first discovered specimens. Currently, Chiniquodontidae includes two genera and six species. Here, we apply the computed tomography (CT-scan) method to describe and revise the morphology of one of the best-preserved chiniquodontid specimens (MCP 1600 PV, holotype of 'Probelesodon' kitchingi Sá-Teixeira, 1982) from Brazil, which allowed the visualization of sutures and the segmentation of each bone. The CT-scan data also revealed some previously undescribed traits due to the presence of matrix covering structures of the skull. In addition, the morphological comparisons revealed differences of MCP 1600 PV in relation to the other chiniquodontids, and eight discrete cranial features not related to ontogeny indicate that 'Probelesodon' kitchingi might not be included within Chiniquodon theotonicus Huene, 1936. Therefore, we consider the species valid but propose the new combination Chiniquodon kitchingi. Moreover, the results obtained highlighted the necessity of a reassessment of the family, as well as the description of new specimens, morphometric analyses, and use of CT-scan, when feasible.