A new non-mammaliaform eucynodont from the Carnian-Norian Ischigualasto Formation, Northwestern Argentina

A new small eucynodont, a non-mammaliaform cynodont, has been identified from the Carnian-Norian Ischigualasto Formation in northwestern Argentina. This discovery enriches the diverse fossil record of the region and provides insights into the evolutionary history of cynodonts during this period. The new taxon is characterized by distinct morphological features, including an extended palatal process of the premaxilla and a unique postorbital bar angle. Phylogenetic analysis places this genus within Probainognathia, more derived than Probainognathus but closely related to Ecteninion and Trucidocynodon. The study proposes a new clade, Ecteniniidae, which represents the sister-group of Prozostrodontia. Additionally, it highlights that the Scaphonyx-Exaeretodon-Herrerasaurus biozone in Ischigualasto exhibits similar cynodont diversity to contemporaneous zones in Southern Brazil, challenging previous assumptions about biogeographical patterns during this time.

N. Martínez, R., Fernandez, E., & A. Alcober, O. (2013). A new non-mammaliaform eucynodont from the Carnian-Norian Ischigualasto Formation, Northwestern Argentina. Revista Brasileira de Paleontologia, 16(1), 61–76. https://doi.org/10.4072/rbp.2013.1.05