First natural endocranial cast of a fossil snake (Cretaceous of Patagonia, Argentina) Laura N. Triviño1, Adriana M. Albino2, María T. Dozo3 and Jorge D. Williams1 1CONICET, Sección Herpetología, Museo de La Plata, Universidad Nacional de La Plata, Paseo del Bosque s/n, B1900FWA La Plata, Argentina. 2CONICET, Departamento de Biología, Universidad Nacional de Mar del Plata, Funes 3250, B7602AYJ Mar del Plata, Argentina. 3 CONICET, Centro Nacional Patagónico, Instituto Patagónico de Geología y Paleontología, Boulevard Brown 2915, U9120ACD Puerto Madryn, Argentina. Short title: First endocranial cast of fossil snake. Corresponding autor: Laura N. Triviño,
[email protected]. CONICET. Sección Herpetología, Museo de La Plata, Universidad Nacional de La Plata, Paseo del Bosque s/n, B1900FWA, La Plata, Argentina This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as an ‘Accepted Article’, doi: 10.1002/ar.23686 This article is protected by copyright. All rights reserved. The Anatomical Record Page 2 of 38 ABSTRACT In this study, we describe a natural endocranial cast included in a partially preserved medium-sized skull of the Upper Cretaceous South American snake Dinilysia patagonica. The endocast is composed of sedimentary filling of the cranial cavity in which the posterior brain, the vessels, the cranial nerves, and the inner ear surrounded by delicate semicircular canals, are represented. It is simple in form, with little differentiation between the three main areas (Forebrain, Midbrain and Hindbrain), and without flexures.