A new species of dromaeosaurid dinosaur being named Dineobellator notohesperus has been discovered by a team of U.S. paleontologists.
Dineobellator notohesperus. Image credit: Sergey Krasovskiy.
Dineobellator notohesperus lived some 67 million years ago (Cretaceous period) in what is now New Mexico.
Its partial skeleton was recovered from the Upper Cretaceous rocks of the San Juan Basin.
The ancient predator stood only about 1 m (3.3 feet) at the hip and was about 2 m (6.6 feet) long — similar in size to famous dromaeosaurids Velociraptor and Saurornitholestes.
“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,” said Dr. Steven Jasinski, a paleontologist at the University of Pennsylvania, State Museum of Pennsylvania and the Don Sundquist Center of Excellence in Paleontology.
While not all of Dineobellator notohesperus’ bones were recovered, bones from the forearm have quill nobs — small bumps on the surface where feathers would be anchored by ligaments — an indication that the dinosaur bore feathers in life, similar to those inferred for Velociraptor.
Features of the animal’s forelimbs, including enlarged areas of the claws, suggest this dinosaur could strongly flex its arms and hands. This ability may have been useful for holding on to prey — using its hands for smaller animals such as birds and lizards, or perhaps its arms and feet for larger species such as other dinosaurs.
Skeletal reconstruction of Dineobellator notohesperus. Individual scale bars – 2 cm. Image credit: Jasinski et al, doi: 10.1038/s41598-020-61480-7.
Dineobellator notohesperus’ tail also possessed unique characteristics. While most dromaeosaurids’ tails were straight and stiffened with rod-like structures, the tail of this dinosaur was rather flexible at its base, allowing the rest of the tail to remain stiff and act like a rudder.
“Think of what happens with a cat’s tail as it is running. While the tail itself remains straight, it is also whipping around constantly as the animal is changing direction,” Dr. Jasinski said.
“A stiff tail that is highly mobile at its base allows for increased agility and changes in direction, and potentially aided Dineobellator notohesperus in pursuing prey, especially in more open habitats.”
Dineobellator notohesperus provides a clearer picture of the biology of North American dromaeosaurids, especially concerning the distribution of feathers among its members.
“As we find evidence of more members possessing feathers, we believe it is likely that all the dromaeosaurids had feathers,” Dr. Jasinski said.
“The discovery also hints at some of the predatory habits of a group of iconic meat-eating dinosaurs that lived just before the extinction event that killed off all the dinosaurs that weren’t birds.”
The discovery is reported in a paper published in the journal Scientific Reports.
_____
S.E. Jasinski et al. 2020. New Dromaeosaurid Dinosaur (Theropoda, Dromaeosauridae) from New Mexico and Biodiversity of Dromaeosaurids at the end of the Cretaceous. Sci Rep 10, 5105; doi: 10.1038/s41598-020-61480-7
