On new Triassic Therapsids found in the center of the province of Mendoza, Argentina

Abstract

A brief account is given on a new Triassic tetrapod fauna, found by the geologist Dr. E. González Díaz, from the Dirección Nacional de Geología y Minería. This fossiliferous area is located 35 km southwards from San Rafael city, in the center of the province of Mendoza, Argentina.

Till now, only Therapsida are known to compose the fauna: a Kannemeyerid Dieynodont and a Diademodontid Cynodont. A short diagnosis is given of each species, their principal affinities being stated.

For the Kannemeyerid, Kannemeyeria argentinensis n. sp., the affinities are evident with K. simocephalus (Watson 1948, fig. 17). The Diademodontid, Pascualgnathus polanskii n. g. et n. sp. is closely related to Diademodon and in lesser degree to Cricodon.

A Lower Middle Triassic age, Anisian, is assigned to this tetrapod bearing formation, on account of its closer affinity with the Cynognathus zone fauna, rather than with any other Upper Triassic fauna.

It is believed that the remarkable atfinities of these Argentine species to Kannemeyeria and Diademodontids of similar age from Africa, might give more solid arguments to think that some faunistic groups migrated directly from South Africa to South America during Lower or Middle Triassic times. The species from San Rafael may be considered as paleontological proof of the problem of continental drift, on which recent geological advances postulate a conncetion between Africa and South America during Lower to Middle Triassic at least (vide Cox, 1965).