THEROPOD REMAINS FROM THE BAJADA COLORADA FORMATION (BERRIASIANVALANGINIAN) FROM NEUQUÉN PROVINCE, ARGENTINA

JUAN IGNACIO CANALE; SEBASTIÁN APESTEGUÍA; PABLO A. GALLINA; ALEJANDRO HALUZA; GIANECHINI, FEDERICO A.; LEONARDO JAVIER PAZO

Plaza Huincul

Jornada; Reunion de Comunicaciones de la Asociacion Paleontologica Argentina; 2014

Museo Carmen Funes

We describe here the first theropod materials from the type locality of the Bajada Colorada Formation, including an axis, a proximal left tibia, and isolated teeth. The axis (MMCh-PV-67) has an anteroposteriorly long, dorsally convex and thin neural spine, bearing one pneumatic opening in the centrum, and long and pointed epipophyses. Its size and morphology agree with those of noasaurids. The tibia (MMCh-PV66) lacks the incisura tibialis, and has a low, sharp and proximally positioned fibular crest, resembling abelisaurid tibiae. Among teeth we recognize three morphotypes. Morphotype 1 is represented by one large, blade-like, non-recurved crown (MMCh-PV-68-1), bearing denticles (4/mm), with interdenticular sulci in both carinae, as occurs in abelisaurids. Morphotype 2 is represented by four smaller teeth (MMChPV-68-2 to 5), with tall crowns, slightly curved, and elliptical in cross-section, with denticles (4/mm) restricted to the distal carina, as in noasaurids. Morphotype 3 is represented by a single, large and slightly curved crown (MMCh-PV-68-6). It is labiolingually compressed, with tranverse enamel banding, and bears denticles (4/mm) in the distal carina. The mesial carina exhibits worn denticles restricted to the apical half. Its morphology resembles that of basal tetanurans. It is remarkable that both the tibia and the axis match well with the size and assignation of morphotypes 1 and 2. The Bajada Colorada theropod record, including a 2 meters long possible noasaurid, a large abelisaurid (7?8 mts.) and a single tetanuran tooth, provides a first glimpse of the poorly known theropod diversity of the earliest Cretaceous ecosystems of Patagonia.