CONICET | Buscador de Institutos y Recursos Humanos

A phylogenetic analysis of all Eocene taxa assigned to Notopithecinae has been conducted, evaluating relationshipsamongst notopithecines, basal interatheriids and Interatheriinae. Other groups of native ungulates were also included. Newdental and postcranial characters are considered with respect to previously published data; some characters are evaluated innotoungulates for the first time. Two different searches were performed under parsimony and equal weights. The inclusionof postcranial characters strongly influenced tree topology. The most significant result of the phylogenetic analysis wasthe identification of a novel monophyletic group, including species traditionally grouped as Patagonian Notopithecinae.The notopithecid? name is linked to the new clade defined as the clade stemming from the most recent common ancestorof the species Notopithecus adapinus, Antepithecus brachystephanus, Transpithecus obtentus and Guilielmoscottiaplicifera. This phylogeny supports the main morphological differences of the new clade with respect to InteratheriinaeInteratheriidae. In consequence, a diagnosis is proposed based on phylogenetic results, to which some other morphologicalcharacters are added. The Chilean basal interatheriids Johnbell and Ignigena as well as Punapithecus (Argentinean Puna)are excluded from the notopithecid clade, implying biostratigraphical and biogeographical changes. Notopitheciddistribution now becomes restricted to the middlelate Eocene part of the Sarmiento Formation outcropping in centralChubut and north-east Santa Cruz provinces, Argentina. Other extra-Patagonian records of notopithecids are notconfirmed. The resulting phylogeny resolves some relationships within basal interatheriids differently from previousanalyses. Interatheriinae is not recovered as a monophyletic group, and Oldfieldthomasiidae and Henricosborniid areparaphyletic. The position of the Archaeopithecidae Acropithecus rigidus is controversial; it appears at the base of theTypotheria lineage or in the notopithecid clade, but systematic taxonomy and phylogenetic relationships amongst membersof Archaeopithecidae remain to be established.