A new carnivorous feathered dinosaur, coyote-sized with razor-sharp teeth and claws, has been discovered in New Mexico’s San Juan Basin. The small but formidable predator called Dineobellator would have stalked these open floodplains 70 million years ago.
Steven Jasinski, a paleontologist at the State Museum of Pennsylvania and lead author of the study in Scientific Reports, says Dineobellator is a new species from the Late Cretaceous (70-68 million years ago) that belongs to dromaeosaurid, a group of clawed predators closely related to birds. These rare fossils have features that suggest raptors were still trying out new ways to compete even during the dinosaurs’ last stand—the era just before the extinction event that wiped them out 66 million years ago. “This group was still evolving, testing out new evolutionary pathways, right at the very end before we lost them,” Jasinski notes.
The bones from this new specimen bear the scars of a combative lifestyle and suggest some unusual adaptations of tail and claw that might have helped Dineobellator notohesperus hunt and kill. The name Dineobellator pays homage to the dino’s tenacity and that of the local Native American people. Diné means ‘the Navajo people,’ while bellator is the Latin word for warrior.
“Due to their small size and delicate bones, skeletons of raptors like Dineobellator are extremely rare in North America, particularly in the last 5 million years of the Age of Dinosaurs,” says David Evans, a paleontologist at the Royal Ontario Museum and the University of Toronto, who wasn’t involved in the study. “Even though it is fragmentary, the skeleton of Dineobellator is one of the best specimens known from North America for its time, which makes it scientifically important and exciting.”
Over four field seasons between 2008 and 2016, Jasinski and colleagues unearthed 20 fossils from a single creature’s skeleton, including parts of the skull, teeth, fore and hind legs, ribs and vertebrae. Dineobellator’s forearms feature quill knobs, bumps found on the bones of dinosaurs or birds that reveal where feathers once attached. Like its relative Velociraptor, this newfound animal was about the size of a coyote or large barnyard turkey, Jasinski says, but probably punched above its weight as a predator.
The fossils indicate the dinosaur suffered a rib injury, but bone regrowth shows that it survived and healed. But this Dineobellator wasn’t so fortunate with an injury to its hand claw. “The hand claw injury doesn’t show any bone regrowth, so it looks like it happened either right at death or just before,” Jasinski says.
Dineobellator’s unusual features include its forelimbs, which appear to be an uncommon shape that would have maximized muscle power to make them very strong, a trait Jasinski suggests was accentuated by claws on both hands and feet. “Their grip would have been far stronger than what we see in the other members of this group,” he says.
Fossils from the animal’s tail also suggest an intriguing anatomy. Most similar dinosaurs have stiff tails reinforced with bones or tendons that would have helped with balance and aided running. “What these animals have … is a lot of mobility at the base of the tail where it attaches to the hips,” Jasinski says. “If you think about how a cheetah attacks, their tail is whipping all over the place because they have to change directions very quickly so it increases agility. That’s what this animal would have been able to do, that others in its group would not. It makes this animal agile and a very good pursuit predator.”
Paleontologist Alan Turner, of the American Museum of Natural History and Stony Brook University, cautions that without a full skeleton, the remains are too fragmentary and scattered to make serious inferences about Dineobellator’s tail or claws. “A couple of vertebrae do give you a glimpse of what the tail looked like, but if you don’t have an entire tail, or the part of the backbone that the tail attaches to, I’d be reticent to make a definitive statement about tail mobility.” But, he says, this study fills in gaps for a period that’s lacking in samples and offers a glimpse into the dromeosaurs of the time.
David Evans echoed that point. “More complete fossils and comparative functional analyses are needed to demonstrate whether Dineobellator was a particularly strong or adept predator. Dineobellator shows us more skeletons are out there, waiting to be found,” he says.
Evans agrees with the study authors that the fossils in hand demonstrate that close relatives of Velociraptor were diversifying during the last days of the Age of the Dinosaurs. “Importantly, it shows that the raptors in the southern part of western North America were distinct from those in the north, and suggests these differences may have been driven by different local ecosystem conditions.”
Other excavations have given scientists a reasonably good idea of the menagerie of animals that shared Dineobellator’s ecosystem, an open floodplain habitat in modern-day New Mexico that was growing increasingly distant from the receding shoreline of the Western Interior Seaway.
Ojoceratops, a horned beast very much like Triceratops, was fairly common as was long-necked sauropod Alamosaurus. “We have evidence of a small tyrannosaurid, something like T. rex but considerably smaller,” Jasinski says. “There are duck-billed dinosaurs, hadrosaurids, that are relatively common, there are lots of turtles, crocodilians have been common all over the place, and evidence of early birds there as well that would have been living with this thing.”
As for how Dineobellator and its kin fit in, Turner says that’s a matter of speculation. “Just size-wise, your average North American or Asian dromeosaur might be along the lines of foxes or coyotes,” he notes, adding that like those mammals, Dineobellator might have existed in substantial numbers as a kind of ubiquitous predator. “That sort of general predatory niche is probably where a lot of these dromeosaurs were falling out.”
While the individual Dineobellator in the study appears to have met a violent end it seems likely that it and its relatives also enjoyed their share of success. “They have sharp teeth and nasty claws on their feet,” Turner notes. “They aren’t these big intimidating things, but I still wouldn’t want to have a run-in with one.”