A NEW SPECIES OF CERDOCYON (CARNIVORA, CANIDAE) FROM THE LUJANIAN OF BUENOS AIRES (ARGENTINA)?

RAMIREZ, M. A.

Mendoza

Congreso; 4th International Paleontological Congress; 2014

Cerdocyon Hamilton-Smith is a monospecific genus that in the present inhabits from Colombia and Venezuela to the Parana?s delta of the Buenos Aires Province in Argentina. Its fossil record is restricted to the Lujanian of Minas Gerais, Brazil, and some mentions in archeological sites from Rio Grande do Sul in Brazil. In the present contribution a specimen from the Lujanian of the Frías stream in the locality of Mercedes in the NE of Buenos Aires Province is described. The specimen (MCA 1094) shares some characters with the living species Cerdocyon thous Hamilton-Smith like a short snout, small canines, a small P4, a well developed subangular lobe of the mandible and a dorsoventrally expanded pterygoid fossa of the angular process of the mandible. Some features of this specimen are different from Cerdocyon thous, for example the zygomatic arch is strongly curved in lateral view and not flat as in Cerdocyon thous. Another difference is the slope of the frontal region of MCA 1094 which is strongly pronounced in contrast with the frontal region of Cerdocyon thous which is slightly pronounced. To test the differences in the shape of the skull in lateral view a geometric morphometry analysis was performed including the MCA 1094 and specimens from the living species Cerdocyon thous, using a set of 25 landmarks, performing a procrustes analysis to superimpose the landmark configurations and then a PCA with the specimen aligned. The results of this analysis show differences between the slope of the frontal region of MCA 1094 and the specimens of Cerdocyon thous. The phylogenetic relationships of the fossil specimen were tested in a cladistic analysis using the software TNT resulting in one tree of 3788,084 steps. The results of this analysis show that MCA 1094 forms a moderately supported clade (37% GC values, after 1000 replicates of symmetrical resampling (p=33)) with Cerdocyon thous with the following synapomorphies: a scarcely developed external auditive meatum, a well developed subangular lobe of the mandible, a quadrangular angular process of the mandible, and a high mandibular condyle that reaches the tip of the trigonid of the m1. These results suggest that the specimen represents a new species of Cerdocyon. MCA 1094 also represents the first fossil record of Cerdocyon from Argentina and the southernmost record of the genus