Paleontologists have discovered a new species of carnivorous dinosaur, Joaquinraptor casali. The apex predator stood about 22 feet tall, possessed crushing claws, and, perhaps most startling of all, was found with a piece of ancient crocodile trapped between its teeth.
Researchers writing in Nature Communications describe the latest addition to a group of dinosaurs known as megaraptorans, a mysterious and poorly understood clade of carnivorous theropods characterized by their elongated skulls and mighty forelimbs, each equipped with enormous claws.
The oldest known examples — Phuwiangvenator yaemniyomi and Vayuraptor nongbualamphuensis — were found in Thailand and are thought to date back to the late Valanginian-early Hauterivian stages of the Early Cretaceous period, approximately 130 million years ago. The remains of other species have been found scattered in various parts of the world — specifically in Asia, Australia, and South America, where they appear to have been particularly abundant. This latest specimen might just be the youngest yet.
Digging For Dinosaurs
A team of paleontologists led by Lucio Ibiricu at the Patagonian Institute of Geology and Paleontology discovered the remains in the Lago Colhué Huapi rock formation in Chubut Province, central Patagonia, Argentina. The fossils — which include remnants of arm, leg, and tail bones as well as parts of the dinosaur’s skull and jaw — were buried just a few meters below the surface of the rock, placing it at the very tail end of the Cretaceous period (66 to 70 million years ago).
The remains, although incomplete, are remarkably intact for a dinosaur of its kind and offer an intriguing glimpse into the giant predator’s prehistoric world. While the researchers believe the specimen was just 19 years old when it died and, as such, was not yet fully grown, an adult of this species would have reached (and possibly even exceeded) lengths of 7 meters (23 feet) and weights of 1,000 kilograms (2,200 pounds).
But perhaps most curious of all was the fossil lodged between its jaws, which turned out to be a front leg bone of a crocodyliform — a group of reptiles that includes the ancient ancestors of today’s crocodiles. The most straightforward explanation is that this unfortunate croc was dinosaur prey, and the Joaquinraptor was fossilized mid-dinner.
However, the researchers do point to other possible explanations — the crocodyliform was killed mid-combat, for example, or water currents serendipitously placed the bone in the dinosaur’s jaws at a later point.
Read More: This 100-Million-Year-Old Microraptor Flapped Its Arms While Running
Filling in the Blanks
The discovery adds more depth to our understanding of megaraptorans in general, which, thanks to a small and fragmentary fossil record, remain poorly understood. It supports the belief that the species of Megaraptoridae that migrated to what is now South America during the mid-Cretaceous period underwent a growth spurt, increasing both in terms of size (from 16 to 23 feet) and body weight (660 pounds to 2204 pounds).
It also suggests megaraptorids were versatile creatures able to survive a range of habitats, particularly in the southern areas of what is now South America, where they are thought to have dominated as the region’s apex predator. The Joaquinraptor, for instance, was found in a spot characterized by warmth, humidity, and proximity to the sea — a vastly different environment from the semiarid climes and inland location where other megaraptorid fossils have been found.
“Joaquinraptor is important in revealing that megaraptorans reigned as the apex predators in southernmost South America all the way to the end of the Cretaceous Period, 66 million years ago,” Matt Lamanna, the senior dinosaur researcher at Carnegie Museum of Natural History and one of the study's co-authors, said in a statement.
What’s in a Name?
The new species (Joaquinraptor casali) has been named after Ibiricu’s son, Joaquín, and in homage Dr. Gabriel Andrés Casal, a renowned expert in Cretaceous palaeontology and the geology of central Patagonia. The word “raptor” is Latin for thief.
Read More: 5 Massive Dinosaur Fossils and Where They Were Found
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