Reassessment of Tegehotherium burmeisteri Ameghino 1903–1904 ( Notoungulata , Hegetotheriidae ) and a new phylogenetic analysis of Hegetotheriidae Citation for this article: Seoane, F. D., Cerdeño, E., & Gaetano, L. C. (2023) Reassessment of Tegehotherium burmeisteri Ameghino ( Notoungulata , Hegetotheriidae ) and a new phylogenetic analysis of Hegetotheriidae. Journal of Vertebrate Paleontology . https://doi.org/10.1080/02724634.2023.…

ABSTRACTWithin the notoungulate family Hegetotheriidae, some species have not been analyzed since their original publication more than a century ago. Here we present the first re-evaluation of Tegehotherium burmeisteri, including a detailed description of its holotype in an updated comparative framework, a species presumably coming from the Trelew Member of the Sarmiento Formation (Chubut Province, Argentina). Tegehotherium burmeisteri is included for the first time in a phylogenetic analysis centered in the interrelationships of hegetotheriids and defining clades according to the PhyloCode. Tegehotherium burmeisteri is recovered as a hegetotheriine closely related to Sallatherium and Hegetotherium; Hegetotheriopsis sulcatus is the earliest branch of the clade Hegetotheriidae, whereas Prohegetotherium and Paedotherium turn out to be paraphyletic, reinforcing results obtained in recent studies. The family Hegetotheriidae and both subfamilies, Hegetotheriinae and Pachyrukhinae, are recovered as monophyletic groups and defined phylogenetically, as well as two new clades: Pachyrukhini and Hemihegetotheriomorpha. ACKNOWLEDGMENTSThe authors thank the editors and reviewers (A. Kramarz and an anonymous reviewer) for their useful comments on the manuscript. M. Ezcurra and A. Martinelli (MACN), M. Reguero and S. Bargo (MLP), and M. E. Pérez (MPEF), for making available the collections under their care. M. T. Dozo and F. Busker, for the photographs of MPEF-PV 693 (Medistylus dorsatus). We acknowledge that the TNT program is being made available with the sponsorship of the Willi Hennig Society. This work was partially financed by the project PICT 2017-0797 (to EC), and it is R-468 contribution by FDS and LCG to the Instituto de Estudios Andinos “Don Pablo Groeber” (IDEAN, Buenos Aires).DISCLOSURE STATEMENTNo potential conflict of interest was reported by the author(s).