A new feather dinosaur that lived in New Mexico 67 million years ago is one of the last known surviving species of birds of prey, according to a new publication in the journal Scientific Reports.
Dineobellator notohesperus contributes to our understanding of the paleobiodiversity of the American Southwest and provides a clearer picture of what life in this region was like towards the end of dinosaur rule.
Steven Jasinski, who recently completed his doctoral thesis in the Department of Earth and Environmental Sciences at Penn School of Arts and Sciences, led the work on the description of the new species, working with PhD supervisor Peter Dodson of the School of Veterinary Medicine and Penn Arts and Sciences and Robert Sullivan of the New Mexico Museum of Natural History and Science in Albuquerque.
In 2008 Sullivan found fossils of the new species in Cretaceous rocks of the San Juan Basin in New Mexico. Together with his field team of Jasinski and James Nikas, he collected the specimen on US state with a permit issued by the Bureau of Land Management. The entire specimen was recovered during four field seasons. Jasinski and his co-authors gave the species its official name, Dineobellator notohesperus, meaning “Navajo warrior from the southwest”, in honor of the people who now live in the same region where this dinosaur once lived.
Like its Asian cousin Velociraptor, the dineobellator belongs to a group of dinosaurs known as dromaeosaurs. The members of this group are commonly referred to as “raptor” dinosaurs thanks to movies like “Jurassic Park” and “Jurassic World“. But unlike the horrible beasts depicted in the film, the dineobellator was only about 1 meter (3.5 feet) at the hip and, at 6 to 7 feet (about 2 meters) long, was much smaller than its Hollywood counterparts.
Raptor dinosaurs are generally small, lightly built predators. Consequently, their remains are rare, especially from the southwestern United States and Mexico. “While dromaeosaurs are better known from places like the northern United States, Canada and Asia, little is known about the group further south in North America,” says Jasinski.
Although not all of this dinosaur‘s bones could be recovered, the bones of its forearm have quill pimples – small bumps on the surface where feathers would be anchored by ligaments – indicating that the dineobellator carried feathers in its life, similar to those inferred for the Velociraptor.
Features on the animal’s front limbs, including enlarged areas of the claws, suggest that this dinosaur was able to bend its arms and hands quite a bit. This ability may have been useful for holding on to prey, using his hands for smaller animals such as birds and lizards, or perhaps his arms and feet for larger species such as other dinosaurs.
His tail also possessed unique characteristics. While the tail of most birds of prey was straight and stiffened with rod-shaped structures, the tail of the dineobellator was quite flexible at its base, so that the rest of the tail remained stiff and acted like an oar.
“Imagine what happens to the tail of a cat when it walks,” says Jasinski. “While the tail itself remains straight, it also whips around constantly as the animal changes direction. A stiff tail, which is very flexible at its base, allows for increased agility and directional changes and could help the dinebellator track prey, especially in more open habitats.
This new dinosaur provides a clearer picture of the biology of North American dromaeosaurid dinosaurs, particularly with regard to the distribution of feathers among its members.
“Since we find evidence that more members had feathers, we believe it is likely that all dromaeosaurs had feathers,” says Jasinski. The discovery also points to some of the predatory habits of a group of iconic carnivorous dinosaurs that lived just before the extinction event that killed all dinosaurs that were not birds.
Jasinski plans to continue his field research in New Mexico in the hope of finding more fossils.
“With a lot of searching and a little luck, this dinosaur was found weathering out of a small hillside,” he says. “We hike so much and it’s easy to miss something or just walk on the wrong side of a hill and miss something. We hope that the more we look, the greater the chance of finding more of Dineobellator or the other dinosaurs that lived next to him.
Steven E. Jasinski is Curator of Paleontology and Geology at the State Museum of Pennsylvania and received his doctorate from the Department of Earth and Environmental Science at the School of Arts and Sciences at the University of Pennsylvania.
Peter Dodson is Professor of Veterinary Gross Anatomy at the School of Veterinary Medicine and Professor of Earth and Environmental Sciences at the School of Arts and Sciences at the University of Pennsylvania.
Robert Sullivan is a research fellow at the New Mexico Museum of Natural History and Science in Albuquerque.