Estudio tafonómico de un nuevo dinosaurio saurópodo de la Formación Allen (Cretácico Superior) en el Área Natural Protegida Paso Córdoba, General Roca, Río Negro, Argentina

Abstract

n this final degree Thesis, the Taphonomic and paleoenvironmental characteristics of a new paleontological site which sauropod dinosaur remains (IIPG-PCor1) from the Allen Formation, Paso Córdoba (Río Negro, Argentina), Upper Cretaceous of the Neuquén Basin, were analyzed. The material consists of fourteen bone elements that include, three articulated cervical vertebrae, eleven fragments of appendicular bones which were disarticulated but associated ossified tendons. The latter have very little integrity and are randomly scattered throughout the site. Two abelisaurid theropod teeth were found close to the vertebrae. Based on sedimentological and stratigraphical data of the studied area, shallow lake systems that transitionally to arid conditions, culminating in a coastal aeolian environment with large transversal dunes are interpreted where the dinosaur remains were found. Two cervical vertebrae present moderate elongation, strongly opystocelic, and with the articular faces below the level of the transverse process, thus the material is classified as an Titanosauria indet. The taphonomic and sedimentological information indicates that the animal would have died on the surface of a dry interdune. There, its carcass was used by scavenging theropods present in the place that dismembered and stole bones, in turn, stepping on them and generating broken pieces. The three articulated vertebrae do not appear to have been moved from the position in which the animal died and are aligned in a Northeast direction, perpendicular to the migration of the adjacent dunes. Weathering covered all of the bones, consistent with a long subaerial exposure time. Signs of wind abrasion were detected, ruling out the possibility that they had been transported. The taphonomic mode in which IIPG-PCor1 was preserved in the Paso Córdoba wind system differs from that observed in the Protocerapts found in the Gobi Desert, Mongolia. Here the animals were preserved in excellent condition, thanks to the fact that they were quickly buried in the dune fields, preserving a final position influenced by the forces acting from the environment. Instead, IIPG-PCor1 showed similarities to current analogues, such as elephants from Tsavo, Kenya, and desert camelids from Abu Dhabi, United Arab Emirates. The latter coincided in having long exposure times to the subaerial environment, where the taphonomic alteration mechanisms acted with greater intensity.