Description and Classification

Ekrixinatosaurus was a large carnivorous dinosaur, estimated to be around 7 to 8 meters (23 to 26 feet) long and weighing about 1.5 to 2.5 metric tons (1.7 to 2.8 short tons). Like other abelisaurids, it had a distinctive skull that was relatively short from front to back, deep, and wide, with a roughened, bumpy texture on its outer surfaces. One of its most notable features was its very large head compared to its body size, even for an abelisaurid. Ekrixinatosaurus possessed very short arms with tiny, almost non-functional fingers, a common trait among abelisaurids. Its hind legs, however, were powerful and built for supporting its heavy body and allowing it to move effectively as a predator.

Ekrixinatosaurus belongs to the group Theropoda, which includes most carnivorous dinosaurs. Within Theropoda, it is classified under Ceratosauria and then more specifically within the family Abelisauridae. Abelisaurids were a successful group of predatory dinosaurs that flourished in Gondwana (the southern supercontinent) during the Cretaceous period. Ekrixinatosaurus is often considered part of the subfamily Carnotaurinae, which includes other well-known abelisaurids such as Carnotaurus and Aucasaurus. It shared many characteristics with these relatives, indicating a close evolutionary relationship with other South American abelisaurids like Abelisaurus and Skorpiovenator.

Distinguishing Features

Ekrixinatosaurus had several features that help paleontologists identify it and distinguish it from other dinosaurs:

• An exceptionally large and robust skull relative to its overall body size, even when compared to other abelisaurids.
• The skull bones were thick, and the outer surfaces of the snout and top of the head were highly sculptured and bumpy.
• Very short, stocky forelimbs with greatly reduced fingers, typical of the abelisaurid family.
• Powerful and muscular hind limbs designed for locomotion.
• A relatively short but strong neck, necessary to support its large head.

Paleoenvironment and Diet

Ekrixinatosaurus lived in what is now the Neuquén Province of Argentina. During the Late Cretaceous, this area, represented by the Candeleros Formation, was a dynamic environment consisting of floodplains, braided river systems, swamps, and lakes. The climate was generally warm and seasonal. This ecosystem supported a diverse range of life. Ekrixinatosaurus shared its habitat with giant sauropod dinosaurs like Andesaurus and Limaysaurus, which could have been potential prey, especially their young or sick individuals. It also lived alongside one of the largest land predators ever known, the carcharodontosaurid Giganotosaurus. Other animals in this environment included smaller theropods, ornithopod dinosaurs, crocodiles, turtles, and pterosaurs.

As a large abelisaurid, Ekrixinatosaurus was a carnivore. Its strong jaws and sharp teeth were adapted for hunting and processing meat. It likely preyed upon medium-sized herbivorous dinosaurs available in its environment. The presence of the even larger Giganotosaurus suggests that Ekrixinatosaurus was probably not the apex predator in its ecosystem but filled an important role as a secondary large predator, perhaps specializing in different prey or hunting strategies. It might have hunted in packs or scavenged on carcasses as well.

Significance and Ongoing Research

The discovery of Ekrixinatosaurus has been significant for understanding the diversity and evolution of abelisaurid theropods in South America, particularly during the mid-Cretaceous. Abelisaurids became the dominant large predators across Gondwana after the decline of other groups like the carcharodontosaurids. The relatively complete, though disarticulated, remains of Ekrixinatosaurus provide valuable anatomical information that helps paleontologists better understand the biology of these unique carnivores. Its discovery through rock blasting also highlights one of the many ways important fossils can be brought to light.

Ongoing research on Ekrixinatosaurus and its relatives continues to refine our understanding of their anatomy, size, and lifestyle. Paleontologists are interested in how its unusually large head functioned, particularly in terms of bite force and feeding behavior. Further studies aim to clarify its precise position within the Abelisauridae family tree by comparing its features with newly discovered species. Additionally, research into the Candeleros Formation paleoenvironment helps to reconstruct the complex interactions between Ekrixinatosaurus, other dinosaurs like Giganotosaurus, and their shared ecosystem, providing insights into the dynamics of ancient food webs in Gondwana.