PHYLOGENETIC APPROACH FOR THE EOCENE ARCHAEOPITHECIDAE AMEGHINO, 1897 (MAMMALIA, NOTOUNGULATA) FROM PATAGONIA

VERA, BÁRBARA; REGUERO, MARCELO

Ciudad Autónoma de Buenos Aires

Congreso; 35th Annual Meeting of the Willi Hennig Society y XII Reunión Argentina de Cladística y Biogeografia; 2016

Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"

Archaeopithecidae is a very poorly known group of native ungulates from the early Paleogene of Patagonia (Argentina), whose alpha taxonomy remained obscure since Ameghino?s times. It is traditionally considered as a representative family of the Vacan (early Middle Eocene) and Barrancan (late Middle Eocene) South American Land Mammal ages and it is thought to be morphologically close to the notopithecids. Based on the study of more than 500 specimens curated at several institutions, including type specimens, a taxonomic revision and a phylogenetic approach were performed. Out of the six species originally described into the archaeopithecids, only one morphological pattern is here identified, which shows marked morphological transformations throughout ontogeny that reveal intraspecific variability. In consequence, only one genus and species, Archaeopithecus rogeri Ameghino, are recognized, subsequent synonymies are proposed and previous taxonomic hypotheses discarded. The exhaustive revision has permitted improving the knowledge of A. rogeri and, for the first time, revealing many craniodental characters, which allow amending its diagnosis and differentiating this taxon from other Eocene notoungulates. Archaeopithecus rogeri is characterized by the complete and rooted dentition, which is relatively higher than that of other coetaneous short-crowned notoungulates. The phylogenetic analysis, using 28 terminal taxa and 86 morphological characters, yielded 29 most parsimonious trees in which A. rogeri does not branch with any group or family of Notoungulata, disagreeing previous hypothesis that related it to Oldfieldthomasiids or Notopithecids. On the contrary, in our results A. rogeri appears as sister to the remaining taxa, including notopithecids, oldfieldthomasiids, interatheres, hegetotheres and mesotheres.