Description and Classification

Viavenator was a meat-eating dinosaur that walked on two powerful hind legs. Like other abelisaurids, it had a fairly large head with a short snout, very tiny arms, and a muscular body. Paleontologists estimate that Viavenator grew to be about 5 to 6 meters (16 to 20 feet) long, making it a medium-sized predator for its time. The bones discovered so far include parts of its neck, back, tail, hips, and hind legs. These bones show that Viavenator had a strong but relatively lightweight skeleton, with many air pockets in its vertebrae, similar to modern birds.

Viavenator belongs to a family of theropod dinosaurs called Abelisauridae. This group is known for its unusual, often bumpy or horned skulls and extremely reduced forelimbs. Within this family, Viavenator is considered part of a subgroup called Brachyrostra, which means “short snouts.” This group includes other famous South American abelisaurids like Carnotaurus, which had prominent horns, and Skorpiovenator. Some studies suggest Viavenator is closely related to Carnotaurus in a smaller group called Furileusauria.

Distinguishing Features

Scientists can tell Viavenator apart from other dinosaurs, especially other abelisaurids, by looking at specific details of its bones. Some of its key features include:

• A sharp ridge, called a keel, running along the bottom of its neck bones (cervical vertebrae), which was more developed than in many other abelisaurids.
• The main bodies of its backbones (dorsal vertebrae) were longer than those of some of its close relatives.
• Its vertebrae had many hollow spaces, making them lighter, which is a common trait in theropods but pronounced in Viavenator.
• Specific details in the shape and connections of its leg bones, particularly the tibia and fibula.

Paleoenvironment and Diet

Viavenator lived in an environment that was quite different from Patagonia today. During the Santonian stage of the Late Cretaceous, the area where its fossils were found, known as the Bajo de la Carpa Formation, was a landscape of rivers, streams, and plains. The climate was likely semi-arid, with distinct wet and dry seasons. Viavenator shared this habitat with a variety of other creatures.

Other dinosaurs living alongside Viavenator included large, long-necked sauropods like Bonitasaura, which might have been a source of food, especially for younger or sick individuals. Smaller theropods, such as alvarezsaurids (small, insect-eating dinosaurs), and possibly dromaeosaurids like Neuquenraptor, also inhabited the region. There were also plant-eating ornithopod dinosaurs. Besides dinosaurs, the ecosystem included crocodiles, turtles, snakes, and flying reptiles called pterosaurs. As a carnivorous abelisaurid, Viavenator would have hunted other animals. Its prey likely consisted of smaller dinosaurs, young sauropods, and possibly other vertebrates. Abelisaurids are generally thought to have had powerful bite forces suited for taking down medium-sized prey.

Significance and Ongoing Research

The discovery of Viavenator is important because it adds another piece to the puzzle of dinosaur diversity in South America during the Late Cretaceous. It helps scientists understand how abelisaurid dinosaurs evolved and spread across the continent. The relatively well-preserved bones of Viavenator (even without a complete skull) provide valuable information about the anatomy of these predators, especially for the Brachyrostra group.

Viavenator also shows that abelisaurids were already diverse and successful somewhat earlier in the Late Cretaceous (Santonian stage) than previously thought for some regions of Patagonia. Ongoing research includes more detailed study of the Viavenator fossils to learn more about its biology and movement. Scientists also continue to compare Viavenator with other abelisaurids like Carnotaurus, Aucasaurus, and Skorpiovenator to clarify their family tree. Future fossil discoveries in the Bajo de la Carpa Formation could uncover more specimens of Viavenator or other animals from its ecosystem, giving us an even clearer picture of this ancient world.