Exceptionally preserved skeletons of the Cretaceous snake Dinilysia patagonica Woodward, 1901

Abstract

For over one hundred years the Upper Cretaceous snake Dinilysia patagonica has been known from only the holotype skull and associated vertebrae (Smith-Woodward, 1901; Estes et al., 1970; Frazetta, 1970; Hecht, 1982; Rage and Albino, 1989; Albino, 1996). Recent fieldwork near Neuquen, Argentina, has produced a large number of exceptionally well-preserved skulls and skeletons of Dinilysia that preserve osteological features missing in the holotype. This new information is timely as recent studies of snake phylogeny have relied upon incomplete descriptions of Dinilysia (Caldwell, 1999; Scanlon and Lee, 2000; Tchernov et al., 2000). Our study of the new fossils indicates that Dinilysia was a large-bodied snake with an aniliid/ xenopeltid-like middle-ear osteology, and an anguimorph-like hypapophyseal/intercentrum anatomy. These new data will certainly impact future studies of snake phylogeny. We provide the first diagnosis of Dinilysia patagonica Smith-Woodward, 1901, along with a preliminary description of the new material, followed by discussion of two important osteological features (i.e., postorbital vs. jugal, absence of a crista circumfenestralis).