A partial skeleton of a seriema (Aves, Cariamidae) from the Santa Cruz Formation (early Miocene) of Patagonia.

NORIEGA, J.I.; MAYR, J.; VIZCAINO, S.F.; BARGO, M.S.

La Rioja

Jornada; XXVII Jornadas Argentinas de Paleontología de Vertebrados; 2013

CRILAR.CONICET

Cariama santacrucensis Noriega, Vizcaíno and Bargo was described as a seriema based on a basicranium coming from the early Miocene of Patagonia. Based on the original description and figures, it was latter classified in a new genus, Noriegavis Agnolin, and suggested its removal from Cariamidae, considering the species to be of indeterminate phylogenetic affinities within Cariamiformes. Here we present a partial skeleton of the same taxon recently recovered from the same stratigraphic unit of the holotype (Ea. La Costa Member of the Santa Cruz Formation) at the Monte Tigre coastal locality, 20 km south of the holotype provenance. The specimen (MPM-PV 15049, Museo Regional Provincial P.M.J. Molina) includes a skull with its beak and a portion of the ramus mandibulae, partial sternum and pelvis, fragmentary proximal humerus, proximal and distal ulnae, femur, incomplete tibiotarsus, midsection of shaft and distal ends of tarsometatarsi, and a pedal and manus digits. Its overall morphology is very similar to extant seriemas. The elongation and slenderness of the tarsometatarsus, measuring more than ten times the width of its distal end, and the presence of a sulcus for musculus extensor hallucis longus on medial surface of distal shaft are two synapomorphies supporting the original assignment to Cariamidae and being absent in other fossil cariamiforms. Further detailed comparisons and phylogenetic analysis will elucidate if Noriegavis merits to be recognized as a valid genus.