Abstract

DERACO, María V.; POWELL, Jaime E.  and  LOPEZ, Guillermo. First Leontiniid (Mammalia, Notungulata) From The Lumbrera Formation (Santa Bárbara Subgroup, Salta Group-Paleogene) Of Northwestern Argentina. Ameghiniana [online]. 2008, vol.45, n.1, pp.83-91. ISSN 1851-8044.

Coquenia bondi gen. nov. et sp. nov., the first leontiniid of the Lumbrera Formation, is described. It was found at a new fossiliferous site called El Simbolar, situated north of Pampa Grande, Salta province, Argentina. It is represented by the skull and jaw with teeth. The teeth are brachyodont. The dental formula is 3/3; 1/1; 4/4; 3/3. Caniniform incisors, with lingual and labial cingulum. This feature associated with an I2 more developed than I1 and I3 indicates that this new taxon is a leontiniid. The crown of the upper canine is rotated, and has a lingual and labial cingulum. Upper premolars have an anterolingual cingulum which determines a small basin situated just in front of the protocone. Premolars increase greatly in size from the P1 to P4, being the P1 highly reduced. Upper molars show a lingual cingulum. All the molars have a posterior fossa. The M3 is wider towards to the base on its lingual side. Although Lumbrera Formation was considered Casamayoran in age, the taxon described in this paper, and other unpublished notoungulate remains found in the same stratigraphic level, suggests that the red beds overlaying the "Faja Verde II" would be substantially younger and could be interpreted as Mustersan or even grounger in age. These layers could be correlated with those of Casa Grande Formation in Jujuy province (Argentina).

Keywords : Notoungulata; Leontiniidae; Argentina; Paleogene; Biostratigraphy.