Cranial anatomy of an Eocene notoungulate mammal from northwestern Argentina with special reference on the ear region

GARCÍA LÓPEZ, DANIEL ALFREDO; BABOT, JUDITH; GONZÁLEZ, RODRIGO; SCANFERLA, AGUSTÍN

Historical Biology

Taylor & Francis

Año: 2017

0891-2963

A detailed anatomical analysis is here presented focused on a notoungulate skull recovered from sedimentsof the lower part of the Quebrada de los Colorados Formation (LC I; late middle Eocene), cropping outin Salta Province, Argentina. The material was identified as a Toxodontia, although it does not exhibitinformation useful enough for its generic or even familiar assignment. The description was mainly focusedon the basicranium and the auditory region (especially the petrosal and auditory ossicles) given the betterpreservation of these parts in the specimen. Additionally, a phylogenetic analysis was conducted based onprevious studies dealing with a wide sample of South American Native Ungulates. This specimen exhibitssome traits traditionally mentioned for the suborder Toxodontia, such as the horizontal bullar septum, andothers recently regarded as synapomorphies of Notoungulata, including the lateral location of the tensortympani fossa and the expanded medial margin of the petrosal. However, it also shows some unexpectedfeatures for that suborder of notoungulates, such as the presence of a strongly curved promontorium.The study of this skull increases our knowledge of the auditory anatomy of Eocene Toxodontia and yieldsa good opportunity to test current phylogenetic hypothesis, mostly based on Neogene representatives.