'Navajo warrior' dinosaur was a real fighter, with a scar to prove it

[March 27, 2020]  By Will Dunham

WASHINGTON (Reuters) - Scientists have unearthed fossils of a fearsome feathered dinosaur in northwestern New Mexico that was a quick and agile predator that could chase down smaller prey or swarm larger prey in pack attacks 67 million years ago.

And, judging from a telltale scar on one of its menacing sickle-shaped claws, this Cretaceous Period dinosaur also fought with others of its own species.

Scientists on Thursday announced the discovery of Dineobellator notohesperus, a two-legged meat-eater that was relatively small - around 7 feet (2 meters) long and 3 feet (1 meter) tall at the hip, weighing 40-50 pounds (18-22 kg). What Dineobellator lacked in size it made up for with ferocity.

Dineobellator - whose name means "Navajo warrior" to honor the Native American people native to the area - was part of the same dinosaur lineage, dromaeosaurs, as the well-known Velociraptor that lived just a bit earlier in Mongolia.

"It was a swift, active predator. Its claws would have been several inches long and quite formidable, although rather than slicing through meat they probably would be more useful for holding on to things," said paleontologist Steven Jasinski of the State Museum of Pennsylvania in Harrisburg, who led the research published in the journal Scientific Reports.

A four-inch (10 cm) claw on its right hand had a deep gouge whose size and shape indicated the damage was inflicted by another member of its own species.

"We hypothesize it was caused by fighting with another Dineobellator," Jasinski said. "Often times animals in packs fight and squabble over various things, usually resources like food, territory, and even sunlight. It's also possible this was a fight between two males over a mate, or a female fighting off an aggressive male when she might not feel ready to mate."

Reconstruction of Dineobellator notohesperus and other dinosaurs from the Ojo Alamo Formation at the end of the Cretaceous Period in New Mexico, showing three Dineobellator individuals near a water source, with the horned dinosaur Ojoceratops and sauropod dinosaur Alamosaurus in the background, in an illustration released by the State Museum of Pennsylvania in Harrisburg, Pennsylvania, U.S. March 26, 2020. Sergey Krasovskiy/Handout via REUTERS

The dinosaur also had a broken rib that healed, which Jasinski said "not only suggests a hard life but also shows this dinosaur was able to live and deal with at least some injuries."

Dineobellator, armed with rows of cutting teeth, lived near the very end of the age of dinosaurs, about a million years before an asteroid impact wiped them out, inhabiting a floodplain teeming with other dinosaurs including much larger predators and a variety of plant eaters.

Roughly 25 percent of its skeleton was recovered, showing Dineobellator boasted evolutionary innovations setting it apart from other dromaeosaurs with superior grip strength in its hands, enhanced flexion in its arms and a unique tail structure.

"Combining these features suggests Dineobellator would have been a swift, skilled pursuit predator that could run down smaller prey and attack and jump onto larger prey, holding on with stronger forelimbs and a tighter grip," Jasinski said.

"Dineobellator tells us," Jasinski added, "that these dinosaurs were still diversifying and trying out new evolutionary pathways even at the twilight of their existence."

(Reporting by Will Dunham; Editing by Sandra Maler)

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