PHYLOGENETIC RELATIONSHIP OF MACRAUCHENIIDAE (MAMMALIA, PANPERISSODACTYLA, LITOPTERNA) AT GENERA LEVEL

LOBO S. L.; GELFO J. N.; AZEVEDO S. A.

Vitória da Conquista

Congreso; VII Congresso Latinoamericano de Paleontologia de Vertebrados; 2022

Laboratório de Ecologia e Geociências Instituto Multidisciplinar em Saúde Universidade Federal da Bahia

In the last decade, Macraucheniidae systematic has been the focus of several studies to enhance the understanding of the diversity and genera relationships. This contribution proposes a new phylogenetic hypothesis of the Macraucheniidae genera after adding new characters and new outgroups. We included eight non-macraucheniid taxa as outgroups, three Didolodontidae, one Protolipternidae (also considered as a junior synonym of didolodontids), two Proterotheriidae, and two Adianthidae; and a priori we included as macraucheniids the 16 genera that are currently accepted to belong to this family by the other cladistics studies. The matrix used in the analysis comprehends 73 characters, subdivided into cranial (17), upper dentition (24), lower dentition (25), and postcranial (7). The matrix was constructed on Mesquite and the cladistic analysis was conducted on TNT. We performed an implicit enumeration with the assumptions of non-ordered and equal weight characters. The cladistic analysis produced 28 most parsimonious trees of 205 steps long (CI=0.507, and RI=0.660) and the consensus with 213 steps long (CI=0.488, and RI=0.633). The strict consensus tree shows the following relationship between the taxa: (Didolodus (Ernestokokenia, Ricardocifellia, Miguelsoria, (Polymorphis, ((Diadiaphorus, Tetramerorhinus) (Tricoelodus (Proadiantus, ((Pternoconius, (Coniopternium, Cramauchenia, Theosodon)) (Paranauchenia, (Llullataruca, Cullinia, Scalabrinitherium, Huayqueriana, (Oxyodontherium, (Promacrauchenia, (Windhausenia, (Xenorhinotherium, (Macraucheniopsis, Macrauchenia))))))))))))). The genus Polymorphis was recovered as the sister taxon of the clade composed by Proterotheriidae + Adianthidae + Macraucheniidae, not as macraucheniid. Disregarding Polymorphis, all other genera attributed to macraucheniid were recovered as a monophyletic, as well as Proterotheriidae. Adianthidae in contrast was paraphyletic, being the stem group of macraucheniids. There were two macraucheniid clades, one formed by Cramaucheniinae + Theosodon, and the other by all the Macraucheniinae with the addition of Llullataruca, being placed in this subfamily for the first time. The late Pliocene Windhausenia, was recovered as the sister group of “Quaternary macraucheniids”, and Xenorhinotherium as sister group of the Macraucheniopsis + Macrauchenia. Based on the topology found, Polymorphis must be considered as incertae sedis, the Macraucheniidae temporal range is late Oligocene – late Pleistocene / Holocene; Llullataruca became the oldest recorded for the Macraucheniinae; and the cladogenetic event of “Quaternary macraucheniids” should occur before the middle Pleistocene.