New Tertiary Sebecosuchia (Crocodylia: Mesosuchia) from Argentina

Abstract

A new sebecid from the early Eocene of Jujuy, with more generalized characteristics than Sebecus, is described. A tooth from the same formation (Lumbrera Formation, Salta Group) and age, in the province of Salta, is assigned to ?Sebecus sp. Another sebecosuchian comes from the late Eocene of Mendoza. A sebecid from the early Oligocene in Patagonia (Chubut) is the most recent record of sebecosuchians in Argentina. Certain local environments in the Tertiary of South America are inferred on the basis of presence of sebecosuchians and associated herpetofauna. Hypotheses of origin and geographical distribution of the Sebecosuchia s.l. (Langston, 1956; Sill, 1969; Steel, 1973; Buffetaut, 1980; Molnar, 1981) are analyzed. Finally, it is confirmed that ziphodonty arose several times during crocodilian history, and that in order to understand the origin and evolution of the Sebecosuchia it will be necessary to have more and better material.