Description and Classification

Tarascosaurus was a bipedal (two-legged) carnivorous dinosaur belonging to the Abelisauridae family. Dinosaurs in this family, such as the well-known Carnotaurus from South America and Majungasaurus from Madagascar, are characterized by their short, deep skulls, powerful necks, and extremely reduced forelimbs (arms) that were likely non-functional. The fossil evidence for Tarascosaurus is quite limited, consisting primarily of the upper part of a thigh bone (femur) and a few vertebrae from the backbone and tail. These bones, however, show features that are distinctive to abelisaurids. Original size estimates suggested Tarascosaurus was a relatively small member of its family, perhaps around 2.5 to 3.5 meters (8 to 11.5 feet) in length. However, discussions continue among scientists regarding its exact size and build due to the incompleteness of the known material. It was likely a medium-sized predator within its island ecosystem.

Distinguishing Features

Despite being known from only a few bones, Tarascosaurus has some notable characteristics and points of interest:

• It was one of the first definitive abelisaurid dinosaurs to be identified from Europe, which was surprising as most abelisaurids had been found on southern continents (the former supercontinent Gondwana).
• The primary fossils include an incomplete femur and several vertebrae, which, though scarce, provide enough anatomical detail to link it to the Abelisauridae family.
• Its discovery highlighted that abelisaurids were more geographically widespread than previously thought, having also inhabited the islands that made up Late Cretaceous Europe.
• The femur of Tarascosaurus has been noted for being somewhat more slender compared to the femurs of some larger, more robustly built abelisaurids.

Paleoenvironment and Diet

Tarascosaurus inhabited the landmass that is now southern France during the Campanian age. During the Late Cretaceous, Europe was not a single continent but an archipelago of islands in a warm, shallow sea. The environment on these islands likely consisted of coastal plains, subtropical forests, and river systems. As a member of the Abelisauridae, Tarascosaurus was a carnivore, preying on other animals in its habitat. Its diet might have included herbivorous dinosaurs such as the ornithopod Rhabdodon or various nodosaurid ankylosaurs, which were common in Europe at the time. It may also have hunted smaller vertebrates or scavenged carcasses.

Significance and Ongoing Research

The identification of Tarascosaurus was significant because it broadened the known geographical distribution of abelisaurid dinosaurs, confirming their presence in Europe. This discovery has implications for understanding how animals dispersed between Gondwana and the European archipelago during the Cretaceous period. However, because the fossils are so fragmentary, the validity of Tarascosaurus as a distinct genus is debated by some paleontologists. Some consider it a nomen dubium, meaning a “doubtful name,” indicating that more complete fossil material is needed to fully confirm its unique characteristics and its precise evolutionary relationships with other abelisaurids like Abelisaurus. Future discoveries of theropod fossils in France and other parts of Europe are essential for learning more about Tarascosaurus, potentially clarifying its anatomy, size, and ecological role in the unique island ecosystems of Late Cretaceous Europe.