An artist's impression of the plant-eating dinosaur.

Ferocious tyrannosaur dinosaurs may not have been solitary predators as long envisioned, but more like social carnivores such as wolves, new research unveiled on Monday found.

Paleontologists developed the theory while studying a mass tyrannosaur death site found seven years ago in the Grand Staircase-Escalante National Monument in southern Utah, one of two monuments that the Biden administration is considering restoring to their full size after former President Donald Trump shrunk them.

Using geochemical analysis of the bones and rock, a team of researchers with the University of Arkansas determined that the dinosaurs died and were buried in the same place and were not the result of fossils washing in from multiple areas.

 The remains were found in the 90s, 75 km south of Copiapo, by Chilean geologist Carlos Arevalo.

The new Utah site is the third mass tyrannosaur grave site that’s been discovered in North America - bolstering a theory first developed 20 years ago that they lived in packs.

However, more research needs to be done to make that argument, said Kristi Curry Rogers, a biology professor at Macalester College who wasn’t involved in the research but reviewed the finding Monday.

The social tyrannosaurs theory began over 20 years ago when more than a dozen tyrannosaurs were found at a site in Alberta, Canada.

In addition to the tyrannosaurs, researchers have also found seven species of turtles, multiple fish and ray species, two other kinds of dinosaurs and a nearly complete skeleton of a juvenile Deinosuchus alligator.

 Ferocious tyrannosaur dinosaurs may not have been solitary predators as long envisioned.

These other animals do not appear to have all died together.

Paleontology groups have been among those pushing the federal government to restore the Bears Ears National Monument and Grand Staircase-Escalante to their original sizes to protect the region’s rich paleontological and archaeological record.

Interior Secretary Deb Haaland visited southern Utah earlier this month as she prepared to submit recommendations on whether to reverse Trump’s decision to downsize the monuments. Titus said he showed Haaland some of the fossils at his lab during her visit and said she "appreciated getting to see the material.”

"The (Bureau of Land Management) is protecting these fossils as national treasures.” Titus said. "They’re part of the story of how North America came to be and how ultimately we came to be.”