A recent fossil find from Patagonia is changing our understanding of hunting dinosaurs. This newly identified dinosaur, Joaquinraptor casali, roamed the floodplains of Argentina around 67 million years ago, just before the infamous asteroid that wiped out the dinosaurs.
This dinosaur weighed about a ton and stretched nearly 23 feet long. It holds new insights into how its relatives lived right before the end of the Cretaceous period.
Researchers are excited about this discovery not just because the skeleton was largely intact, but also because it had a surprising find—a crocodile-like animal’s arm trapped in its jaws. This suggests Joaquinraptor was a fierce predator.
A Remarkably Complete Skeleton
Fossilized remains were uncovered in 2019, in a region known as Lago Colhué Huapi in Chubut Province, Patagonia. The age of the rocks indicates this dinosaur was one of the last megaraptorids before the mass extinction. Remarkably, much of its skeleton survived, including parts of the skull, vertebrae, ribs, and both fore- and hindlimbs. Matt Lamanna, a paleontologist from the Carnegie Museum of Natural History, remarked that it is “among the most complete megaraptoran skeletons known to science.”
Intriguing Anatomy
Joaquinraptor belonged to a family of carnivorous dinosaurs with distinct features. It had powerful arms with large claws perfect for tearing flesh. Its thick upper arm bone hinted at strong muscles capable of doing serious damage. Interestingly, its teeth were relatively small, suggesting it relied on its claws as much as its bite to capture prey.
Age estimates based on growth rings in the bones revealed that this dinosaur was around 19 years old when it died. These rings help scientists understand the growth patterns of ancient creatures.
A Clue in Its Jaws
The most startling part of the find was the crocodile’s upper arm bone found between the dinosaur’s teeth. Clear bite marks showed that Joaquinraptor may have preyed on crocodiles or scavenged their remains. Lucio Ibiricu, the lead author of the study, stated that this find gives valuable insight into megaraptorans’ diets.
Understanding the Ecosystem
In the Late Cretaceous, megaraptorids like Joaquinraptor were the primary predators in Patagonia. They likely fed on young titanosaurs and duck-billed hadrosaurs. The crocodile limb in its jaws implies a varied diet, possibly including other wetland reptiles. Such findings show how different dinosaur types thrived in diverse environments across regions, a concept known as “provincialism.”
Evolutionary Insights
This discovery places megaraptorids closer to tyrannosaurs, like the well-known T. rex. While T. rex had massive skulls and strong jaws, Joaquinraptor adapted differently. Long jaws and powerful arms suggest various evolutionary pathways for achieving similar predatory roles.
The fossil’s age adds nearly a million years to the previously understood timeline for megaraptorids, showing they thrived right before the mass extinction event. Researchers now have a well-preserved skeleton to compare against other fragmentary fossils, closing gaps in our knowledge about this fascinating group.
Implications for Modern Science
This discovery offers insights into dinosaur evolution and the dynamics of ancient ecosystems. By studying the growth patterns within these fossils, scientists learn how ecosystems might react to drastic environmental changes—lessons that are increasingly relevant today as we face biodiversity crises.
The findings are detailed in the journal Nature Communications, which provides a valuable resource for those interested in the intricate details of paleontological research.
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Nature Communications, Chubut Province, apex predator, Patagonia, Lago Colhué Huapi, carnivorous dinosaurs
