Social T. rex? New research shows that meat eaters hunted in packets

Researchers have discovered a pile of dinosaurs at the Grand Scara-Escalante National Monument – a family of the giant Tyrannosaurus rex – which leads them to conclude that they all died at the same time in the same flood event and stayed together in a “gregarious” unit. social.

The Rainbows & Unicorns career in southern Utah is innovative, as the main narrative around these dinosaurs that roamed the Earth 76.4 million years ago is that they were solitary predators that lacked the sophistication to carry out a coordinated attack to and deliver the next meal.

“That takes a lot of brain power,” said Alan Titus, the Paria River District Paleontologist at the Land Management Bureau.

Titus said the discovery is “somewhat controversial” because the 2014 discovery illustrates the huge dinosaurs that traveled together and probably teamed up in killings – as lion prides or packs of wolves do today. Paleontological researchers have generally rejected the idea that giant meat-eating dinosaurs were capable of such social action.

In this discovery, the scientists discovered a family of four, possibly five T. rex individuals, including a young man about 4 years old and a fully developed adult in the mid-1920s.

The site was dismantled using a series of scientific techniques that reveal that it is the first mass tyrannosaurus to be found in the southern United States. Using a battery of tests and analyzes on the remains of the original site, the researchers found that the dinosaurs perished in a single flood event, were buried in fine mud, dug up and reburied in a sandbar.

“And here it is, a very sad day in southern Utah 76 million years ago,” Titus said.

Alan Titus, Office of Land Management

The findings were published in the open-access scientific journal PeerJ months. They were created by a team of researchers from BLM, the Museum of Nature and Science in Denver, the University of Arkansas, Colby College in Maine and James Cook University in Australia.

The specimens discovered from the unique fossil bone site exceeded expectations even by its high nickname.

Titus said that the name derived from the teasing of former colleagues who erased it with his perpetual enthusiasm for any new discovery.

“It’s always about rainbows and unicorns with me all the time,” he said, but stressed that he told his colleagues no, this was indeed a discovery of rainbows and unicorns.

Researchers remain excited that the career will reveal additional answers as they dig deeper into it.

“The new Utah site adds to the growing body of evidence that tyrannosaurs were complex and large predators, capable of common social behaviors in many of their living relatives, birds,” said project collaborator Joe Sertich, curator of the dinosaurs. at the Denver Museum of Nature and Science. “This discovery should be the tipping point for reconsidering how these top carnivores behaved and hunted in the northern hemisphere during the Cretaceous.”

Titus explained that large predators usually do not team up in search of food – after all, they compete against each other.

But, as in the case of lions and wolves, which have complex and sophisticated social roles, Titus said that a second cousin of the modern dinosaur – the Harris hawk – is the only known predator that hunted in cooperation and participated in the communal growth of young people. their. .

Alan Titus, Office of Land Management

“Localities (such as Rainbows and Unicorns Quarry) that produce information about the possible behavior of extinct animals are particularly rare and difficult to interpret,” said Philip Currie, a world-renowned tyrannosaur expert. “Traditional excavation techniques, complemented by analysis of rare earth elements, stable isotopes and coal concentrations, convincingly show an event of synchronous death at the Rainbows site of four or five tyrannosaurids. Undoubtedly, this group died together, which adds to a growing body of evidence that tyrannosaurids were able to interact as herds. ”

The idea that tyrannosaurs were social with complex hunting strategies was first formulated by Currie over 20 years ago.

Alan Titus, Office of Land Management