Phylogeny and paleobiogeography of Hegetotheriidae (Mammalia, Notoungulata)

SEOANE, FEDERICO DAMIÁN; ROIG JUÑENT, SERGIO; CERDEÑO, MARÍA ESPERANZA

JOURNAL OF VERTEBRATE PALEONTOLOGY

SOC VERTEBRATE PALEONTOLOGY

Lugar: Lawrence; Año: 2017 vol. 37

0272-4634

Hegetotheriidae are one of the most derived families of the Order Notoungulata. It is composed of two subfamilies: Hegetotheriinae, resulting paraphyletic in most of the recent phylogenies, and Pachyrukhinae, historically considered monophyletic. The family is recognized from late Oligocene to Pliocene and is well diversified from its earliest records. Most papers on the family correspond to systematic studies and, in a lesser degree, to its phylogenetic relationships, but the paleobiogeographic approaches are highly rare. A phylogeny was performed, based on a previous matrix, but expanded both in taxa and characters, using TNT. Previous results are supported, as the paraphyly of Hegetotherium Ameghino and Paedotherium Burmeister, and the monophyly of Pachyrukhinae, but new conclusions arise such as the paraphyly of Hemihegetotherium Rovereto and the monophyly of Prohegetotherium Ameghino, and Hegetotheriinae. In this work, a paleobiogeographic analysis on hegetotheriids is performed, by means of the Bayesian method through RASP program, with the aim of estimating the possible ancestral area and vicariance, dispersal, and extinction events. The biogeographic analysis shows that Hegetotheriidae and both subfamilies would have originated in central Patagonia (southeast of Chubut and northeast of Santa Cruz provinces). The analysis also reveals that dispersions were the predominant events, and they are related to dispersions throughout the Cenozoic to lower latitudes as global cooling advanced and new lands emerged.