Presence of the genus eunectes (Serpentes, Boidae) in the neogene of Southwestern Amazonia, Brazil

Abstract

The extant genus Eunectes was first reported for the Middle Miocene of Colombia, represented by the extinct species Eunectes stirtoni. Here, we describe vertebral remains referable to this genus collected in the Neogene Solimões Formation at the Talismã locality, situated on the right-hand bank upstream of the Purus River, in the South of Amazonas State, Brazil. The material consists of isolated mid- and posterior trunk vertebrae characterized by the following combination of features that distinguishes the genus from other Neotropical boids: large size, slightly depressed neural arch, relatively low neural spine, robust and moderately thick zygosphene, with a prominent median tubercle, paracotylar foramen irregularly present, and a strong lateroventral projection of the paradiapophyses on the posterior trunk vertebrae. The presence of Eunectes in the Solimões Formation represents the first fossil record of snakes from the southwestern Brazilian Amazonia and supports the origin of this genus in the Miocene or before. © 2009 Society for the Study of Amphibians and Reptiles.