New Megaraptor Dinosaur from Argentina Found With Crocodile Bone in Its Mouth

Scientists have described a new dinosaur from Argentina, a member of the megaraptoran group, based on a partial skeleton uncovered in Patagonia. The animal, named Joaquinraptor casali, is estimated at about 23 feet (7 meters) long and appears to have used its long arms and enormous claws to seize prey. A crocodile-like jawbone found pressed against its jaws suggests the diet may have included crocodilian relatives, though researchers caution that more fossils are needed to confirm feeding habits.

Fossils recovered from the Lago Colhué Huapi rock formation in Patagonia include a portion of the skull, as well as limb and tail bones. Examined features indicate distinctive traits that led scientists to identify a new species within the megaraptoran lineage. The discovery, published Tuesday in Nature Communications, is described by Lucio Ibiricu of the Patagonian Institute of Geology and Paleontology as helping to fill a gap in what is known about these long-armed carnivores. Federico Agnolin of the Argentine Museum of Natural Science Bernardino Rivadavia, who was not part of the team, said the find represents one of the most complete megaraptorans yet.

The new dinosaur lived about 66 to 70 million years ago, toward the end of the age of dinosaurs, and researchers estimate it died at least 19 years old. The cause of death remains unknown. The team notes that the front leg bone pressed against the jaw belonged to an ancient relative of crocodiles, a clue that may help illuminate its diet and whether it stood near the top of its food chain on the humid prehistoric flood plains of Patagonia.

The skeleton named Joaquinraptor casali is expected to prompt fresh questions about how megatora–megaraptorans—hunted and how they fit into the broader dinosaur family tree. Megaraptorans roamed across what is now South America, Australia and parts of Asia, diversifying into several species over millions of years. In Patagonia, the new find adds to a growing record of Late Cretaceous predators from the region.

Ibiricu named the new dinosaur in memory of his son Joaquin, saying that he would have appreciated the nod to a lifelong interest in dinosaurs. The researchers stress that, while the bones are unusually complete for this group, many questions remain about behavior and ecology. The study was published in Nature Communications.