Description and Classification

Vallibonavenatrix was a medium-sized carnivorous dinosaur, estimated to be around 8 to 9 meters (approximately 26 to 30 feet) in length. Like other theropods, it walked on two legs. As a member of the Spinosauridae family, it is related to other well-known dinosaurs such as Baryonyx from England and the giant Spinosaurus from North Africa. Spinosaurids are characterized by their long, crocodile-like snouts and conical teeth, which were well-suited for hunting fish, although no skull material has been found for Vallibonavenatrix to directly confirm these features.

The classification of Vallibonavenatrix within the Spinosauridae family places it as an important European representative of this group. Some studies suggest it may be more closely related to the Spinosaurinae subfamily, which includes Spinosaurus and Ichthyovenator, rather than the Baryonychinae subfamily. Its sacral vertebrae (those fused to the pelvis) and some features of its dorsal vertebrae are distinct. Notably, some of its back vertebrae possess tall neural spines, suggesting it might have had a low sail or ridge along its back, though likely not as tall or extensive as that of Spinosaurus.

Distinguishing Features

Vallibonavenatrix can be identified by several unique anatomical characteristics, particularly in its pelvis and vertebrae. These features help paleontologists distinguish it from other spinosaurid dinosaurs:

• A distinctively shaped ilium (the largest hip bone) that is relatively tall.
• The presence of a unique notch on the ischium, another bone in the pelvis.
• Tall neural spines on some of its dorsal (back) vertebrae, which are taller than those of Baryonyx but shorter than those of later spinosaurines like Ichthyovenator or Spinosaurus.
• Specific features on its sacral vertebrae, where the spine connects to the pelvis.

Paleoenvironment and Diet

Vallibonavenatrix lived in what is now eastern Spain during the Early Cretaceous. The Arcillas de Morella Formation, where its fossils were found, represents an ancient coastal wetland environment. This ecosystem included extensive river systems, lakes, and deltas, offering a rich habitat for various forms of life. Other dinosaurs found in the same formation include plant-eating ornithopods like relatives of Iguanodon, large sauropods, and other types of theropods.

Based on its spinosaurid classification, Vallibonavenatrix was likely a specialized predator. Spinosaurids are generally believed to have been at least partially piscivorous, meaning they ate fish. Their inferred long snouts and conical teeth, similar to those of crocodiles, would have been effective for grasping slippery aquatic prey. It is probable that Vallibonavenatrix hunted fish in the rivers and lakes of its environment, though it might have also preyed on other small animals if the opportunity arose.

Significance and Ongoing Research

The discovery of Vallibonavenatrix is significant because it adds to the growing understanding of spinosaurid diversity in Europe during the Early Cretaceous. It provides valuable information about the evolution and geographic distribution of these unusual theropods, highlighting the Iberian Peninsula as an important region for their radiation before spinosaurids became more widespread in other parts of the world, like Africa.

The relatively well-preserved pelvic material of Vallibonavenatrix offers important anatomical details not always available for other spinosaurid species. Ongoing research on this dinosaur may include further comparative anatomical studies to refine its exact position within the Spinosauridae family tree. Paleontologists will also continue to search for more fossil material, particularly a skull, which would provide more direct evidence of its feeding adaptations and appearance. Studying Vallibonavenatrix alongside other European spinosaurids like Baryonyx, Camarillasaurus, and Iberospinus helps paint a clearer picture of dinosaur ecosystems in ancient Europe.