You might think that the age of dinosaurs is set in stone, like the fossils they left behind, but paleontologists uncover new species and make new discoveries practically every day. Recently, researchers discovered Joaquinraptor casali, a new genus and species of giant-clawed megaraptor from the late Cretaceous.
Today, the puma rules the Patagonian land while orca patrol the seas, but 66 million years ago the dynamics were different. Hypercarnivorous crocodilians hunted dinosaurs along coastal floodplains, but it wasn’t a one-way relationship. J. casali was discovered with a croc’s leg bone between its jaws, according to a recent study published in the journal Nature Communications.
This Patagonian megaraptor ate ancient crocs for lunch
Found in the Lago Colhué Huapi Formation in Patagonia, Argentina, J. casali may have been the apex predator of its Cretaceous-era domain. It was a member of the mysterious dinosaur group megaraptora, named for their gigantic curving claws.
Members of the group have been found in Asia, Australia, and South America, including the warm, humid floodplains of Patagonia where J. casali roamed. Despite their wide distribution, no complete skeleton has ever been found and there are still a lot of mysteries surrounding the group. Each new discovery, including the discovery of J. casali, fills in some of the gaps in their story.
The fossilized skeleton of J. casali, like the other megaraptorids, is partially complete but well-preserved and partially articulated. Much of the skull, fore-limbs, hind-limbs, ribs, and vertebrae are intact. And, of course, they found the leg bone of an ancient crocodyliform between the dino’s teeth. It’s a pretty strong indication that J. casali snacked on other large predators, but researchers noted the bone could have gotten there some other way. More research is needed to find out for sure if J. casali was chewing on a croc when it met its end.
The remains of J. casali are highly pneumatized (filled with air pockets) like the bones of modern birds. Analysis revealed the specimen was likely a sexually mature adult but not yet fully grown. Its age was estimated at 19 years, based on the fusion of skull bones. Length was estimated at 7 meters (21 feet) from tip to tail and it would have weighed more than a ton while alive.
Unlike many other theropods like T. rex, megaraptorids had powerfully developed forelimbs equipped with hypertrophied unguals on the first and second digit. Put simply, they had humongous claws on the first two fingers, perfect for snatching large prey.
“The singular morphology of the megaraptorid forelimb may have played an important role in the evolutionary success of these theropods in the Late Cretaceous of central and southern Patagonia,” study authors wrote. “The specialized development and capabilities of the forelimb were almost certainly adaptations related to prey capture, and, in the case of Joaquinraptor, these prey items may have at least occasionally included crocodyliforms.”
The evolutionary relationship between megaraptorids and other theropod groups remains a matter of investigation and debate but J. casali provides some clues. Phylogenetic analysis of the new species supports placement within the clade Coelurosauria, making Megaraptora a sister group to Tyrannosauroidea.
Wherever they fit in the long history of dinosaurs, megaraptorids like J. casali carved out their niche violently, with oversized claws and croc-chomping teeth.
For more croc-chomping adventures, catch Lake Placid: Legacy, streaming now on SYFY.