New apex-predator dinosaur Joaquinraptor casali fossilized mid-meal in Patagonia
Nearly complete megaraptorid from the Late Cretaceous era preserves a crocodile-like prey in its jaws
A new species of apex predator dinosaur has been identified from Patagonia: Joaquinraptor casali, a megaraptoran fossilized in the act of feeding on a crocodile-like crocodyliform. The remains date to roughly 66 to 70 million years ago in the late Cretaceous, and were uncovered in the Lago Caolhue Huapi rock formation in southern Argentine Patagonia. The holotype includes a skull, a forelimb, a hind limb and portions of the tail from a single individual, with the humerus of a crocodyliform preserved inside the predator's jaws, offering a rare snapshot of a predator at a meal.
Nature published the study describing the specimen as among the most complete megaraptorans yet found and one of the latest-surviving members of Megaraptoridae. The researchers note that megaaraptorids appear to have been the apex predators in central and southern Patagonian paleoecosystems approaching the end of the Cretaceous. The unusually close association of a crocodyliform humerus with the theropod specimen may provide information on the dietary preferences and feeding strategies of Megaraptoridae. A senior researcher described the discovery as filling a major gap by providing one of the most complete skeletons yet of this group. Lead authors on the study are Lucio Ibiricu of the Patagonian Institute of Geology and Paleontology.
Lead author Lucio Ibiricu named the apex predator Joaquinraptor casali in honor of his departed son. He explained to the Associated Press that the name reflects a sentiment many children have toward dinosaurs and that his son would likely have embraced the discovery.
The new species adds to what scientists know about megaaraptorans, a group distinct from more familiar predators such as Tyrannosaurus rex and Velociraptor. Megaraptorids are characterized by their large claws, which researchers believe played a role in predation, particularly in gripping prey. The Patagonia find strengthens the view that late Cretaceous ecosystems in central and southern Patagonia were home to diverse, apex predator communities, with megaraptorans occupying a top tier in the food web as the end of the Cretaceous period approached.
The specimen’s combination of cranial and limb elements, along with the tail fragments, points to a tall, claw-equipped predator capable of extended pursuits and powerful strikes. The close association of the crocodyliform humerus with the jaw region provides a rare, direct look at feeding behavior during a kill, suggesting that these dinosaurs could tackle sizable prey and consume them relatively quickly before competition or environmental pressures intervened.
The discovery from the Lago Caolhue Huapi formation represents a significant addition to Patagonian paleontology, offering one of the most complete skeletons yet recovered for Megaraptoridae and helping paleontologists reconstruct predator-prey dynamics in southern Patagonian ecosystems during the late Cretaceous. The findings underscore the diversity of predatory dinosaurs that thrived in this region as the era came to a close.
