Fossils of a new dromaeosaur date to the end of the Age of Dinosaurs

Newly discovered species suggests these fierce predators were diversifying right up to the end

Dineobellator notohesperus illustration

Dineobellator notohesperus (illustrated in foreground) was a fierce, feathered predator that lived about 68 million years ago, alongside horned dinosaurs like Ojoceratops and sauropods like Alamosaurus (background).

Sergey Krasovskiy

A wolf-sized warrior, kin to the fierce, feathered Velociraptor, prowled what is now New Mexico about 68 million years ago.

Dineobellator notohesperus was a dromaeosaur, a group of swift, agile predators that is distantly related to the much larger Tyrannosaurus rex. The discovery of this new species suggests that dromaeosaurs were still diversifying, and even becoming better at pursuing prey, right up to the end of the Age of Dinosaurs, researchers say March 26 in Scientific Reports.

That age came to an abrupt close at the end of the Cretaceous Period about 66 million years ago, when a mass extinction event wiped out all nonbird dinosaurs. A gap in the global fossil record for dromaeosaurs near the end of the Cretaceous had led some scientists to wonder whether the group was already in decline before the extinction, says Steven Jasinski, a paleontologist at the State Museum of Pennsylvania in Harrisburg (SN: 4/21/16). The new find suggests otherwise.

D. notohesperus skeleton
A skeletal reconstruction of D. notohesperus shows that the dromaeosaur, one of a group of agile predators, was about the size of a modern wolf. Analyses of over 20 fossil bits revealed that the dinosaur had feathers and was likely stronger than the closely related Velociraptor.S. Jasinski

Since 2008, Jasinski and his colleagues have recovered more than 20 fossilized pieces of the new species from the Bisti/De-Na-Zin Wilderness, a rapidly eroding region of barren badlands in northwestern New Mexico. Analyses of muscle attachment sites on the fossilized forelimbs suggest the dinosaur was unusually strong for a dromaeosaur, with a very tight grip in its hands and feet. That grip, Jasinski says, was likely stronger than that of its famous kinfolk, Velociraptor and Utahraptor, giving the new species extra weaponry in its pursuit of prey.

Like many other dromaeosaurs, D. notohesperus had feathers, evidenced by the presence of quill nobs — bumps indicating where the feathers were attached — on its limbs (SN: 9/19/07). But, like Velociraptor, it probably used the feathers for purposes other than flight, Jasinski says, such as sexual selection, camouflage or added agility while on the hunt.

Carolyn Gramling is the earth & climate writer. She has bachelor’s degrees in geology and European history and a Ph.D. in marine geochemistry from MIT and the Woods Hole Oceanographic Institution.

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