The northernmost South American fossil record of Boa constrictor (Boidae, Boinae) from the Plio–Pleistocene of El Breal de Orocual (Venezuela)

Abstract

Onary-Alves, S.Y., Hsiou, A.S. & Rincón, A.D., July 2016. The northernmost South American fossil record of Boa constrictor (Boidae, Boinae) from the Plio–Pleistocene of El Breal de Orocual (Venezuela). Alcheringa 41, xxx–xxx. ISSN 0311-5518.Boa constrictor is an extant boid widely distributed through the neotropical region, from the north of Central America to central Argentina. The fossil record of the species includes examples from several localities across the Americas that extend beyond the current distribution of the species. Here we report the first Plio–Pleistocene fossils of Boa from Monagas state, Venezuela. The material comes from El Breal de Orocual (Maturín municipality), which is an inactive tar seep deposit emplaced within the Mesa Formation. The specimens consist of two isolated anterior trunk vertebrae, an articulated sequence of six mid-trunk vertebrae and two posterior trunk vertebrae. The vertebrae are attributed to B. constrictor based on the following features: robust and high vertebrae; thick zygosphene with a notched or concave anterior edge; presence of a paracotylar, subcentral and lateral foramina; marked parasagittal ridges; epizygapophyseal process evident on the dorsal surface of the postzygapophyseal articular facets and high blade-like neural spine. The presence of B. constrictor in northern of Venezuela indicates a palaeoenvironment probably like savanna crossed by rivers with riparian forests, and suggests the predominance of a mesothermal climate with a moderate rainfall.Silvio Y. Onary-Alves [silvioyuji@gmail.com], Programa de Pós-graduação em Biologia Comparada, Faculdade de Filosofia, Ciências e Letras, Universidade de São Paulo (USP), Av. Bandeirantes 3900, CEP 14040901, Ribeirão Preto, São Paulo, Brazil; Annie S. Hsiou [anniehsiou@ffclrp.usp.br], Laboratório de Paleontologia, Faculdade de Filosofia, Ciências e Letras, Departamento de Biologia, Universidade de São Paulo (USP), Av. Bandeirantes 3900, CEP 14040901, Ribeirão Preto, São Paulo, Brazil; Ascanio D. Rincón [paleosur1974@gmail.com], Laboratorio de Paleontología, Centro de Ecología, Instituto Venezolano de Investigaciones Científicas (IVIC), Carretera Panamericana Km 11, 1020-A Caracas, Venezuela.