New Feathered Dinosaur From New Mexico Was Among the ‘Last of the Raptors’

new mexico dinosaur

A carnivorous dinosaur that once hunted in northwestern New Mexico was among the last of its kind, paleontologists say — a raptor that lived nearly until the eve, geologically speaking, of the Cretaceous-Paleogene extinction event.

The newly discovered species is represented by a single, incomplete specimen that was found eroding out of a hillside. But enough material was recovered for paleontologists to deem it new to science.

The dinosaur belongs to that group of small, light-bodied meat-eaters that are often popularly referred to by the (frustratingly) unscientific term “raptor.”

Referring to certain theropod dinosaurs as “raptors” is the legacy of the Jurassic Park film franchise, where the term was used loosely and liberally to refer to the genus Velociraptor.

For whatever reason, the word took hold, and since then it’s been taken up in pop-sci circles to refer more broadly to the dinosaurs known as dromaeosaurids.

Dromaeosaurids include all manner of mid-sized, feathered theropods, from Deinonychus to Utahraptor. [Read about two other new dromaeosaurid specimens: “Giant Feathered Dinosaur, With ‘Unprecedented’ Features, Discovered in South Dakota“]

Dineobellator notohesperus dinosaur
An artist’s reconstruction depicts Dineobellator notohesperus, a newly discovered feathered dinosaur from New Mexico. (Credit: Sergey Krasovskiy)

But, Dr. Steven Jasinski, who reported the new species with his colleagues, noted that not many  dromaeosaurids have been found in the U.S. Southwest.

“While dromaeosaurids are better known from places like the northern United States, Canada, and Asia, little is known of the group farther south in North America,” Jasinski said in a press statement.

In honor of where it was found — on federal land near the Navajo Nation — Jasinski and his team named the new species Dineobellator notohesperus, or “Navajo warrior from the Southwest.”

And this new member of the dromaeosaurid family may shed light on the bigger history of American raptors.

At about 1 meter tall and 2 meters long, Dineobellator wasn’t an especially large raptor. But its fossil does bear some striking traits.

For one thing, unlike most dromaeosaurids, the caudal vertebrae — or bones in its tail — have a distinctive shape, convex on one end and concave on the other.

This allowed the vertebrae to fit together snugly, almost like ball and socket joints.

This likely made Dineobellator’s tail more flexible at the base, Jasinski said, while the rest of its tail could stiffen to act like a rudder.

“Think of what happens with a cat’s tail as it is running,” Jasinski said.

“While the tail itself remains straight, it is also whipping around constantly as the animal is changing direction.

“A stiff tail that is highly mobile at its base allows for increased agility and changes in direction, and potentially aided Dineobellator in pursuing prey, especially in more open habitats.”

And insights like this can provide clues about how the dinosaur fit into the ecosystem of Southwestern dinosaurs more broadly.

Writing in the journal Scientific Reports, Jaskinski and his colleagues say that such adaptations “imply that dromaeosaurids were active predators that occupied discrete ecological niches while living in the shadow of Tyrannosaurus rex, until the end of the dinosaurs’ reign.”

Dineobellator also offers new details about perhaps one of the most controversial aspects of theropods: their feathers. [Brace yourself for this controversial feather finding: “T. Rex Didn’t Have Feathers, New Study of Fossil Skin Finds“]

Some of the bones recovered from the specimen are of the forearm, which were found to include quill nobs, little raised holes where feathers had been attached.

Dineobellator will surely not be the last specimen found to have such features, Jasinski said.

“As we find evidence of more members possessing feathers, we believe it is likely that all the dromaeosaurids had feathers,” he said.

Given the location and age of the fossil, Dineobellator also yields information about the larger evolutionary history of those dinosaurs now known as raptors.

dineobellator dinosaur
A skeletal reconstruction of Dineobellator. Note the vertebrae in the tail! (Image by Steven Jasinski)

Jasinski and his colleagues noted that this new species illustrates just how much dromaeosaurids radiated and diversified after they migrated into North America from Asia earlier in the Cretaceous.

“Our analysis suggests multiple faunal interchanges and migrations between Asia and North America in the Late Cretaceous, with potential vicariance occurring into the very end of the Cretaceous in dromaeosaurids, particularly in North America,” the team writes in Scientific Reports.

With the wealth of data provided by just these few bones, Jasinski said he intends to keep searching the arid hills of northwestern New Mexico to learn more about the story of the raptors, right up until their extinction at the end of the Cretaceous Period.

“It was with a lot of searching and a bit of luck that this dinosaur was found weathering out of a small hillside,” he said.

“We do so much hiking, and it is easy to overlook something or simply walk on the wrong side of a hill and miss something.

“We hope that the more we search, the better chance we have of finding more of Dineobellator or the other dinosaurs it lived alongside.”

Citation: Jasinski SE, Sullivan RM, & Dodson P. (2020) New Dromaeosaurid Dinosaur (Theropoda, Dromaeosauridae) from New Mexico and Biodiversity of Dromaeosaurids at the end of the Cretaceous. Scientific reports, 10(1), 5105. PMID: 32218481

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