New Fossil Evidence in Utah Points to T. Rex as Pack Hunters

A recent study by UC Berkeley researchers pinned the total number of T. rex that have ever roamed Earth at a whopping 2.5 billion. Now, the Bureau of Land Management in Utah (or BLM Utah), has announced another T. rex finding that makes the “king lizard tyrants” seem frighteningly prolific: the discovery of confirmatory evidence that a group of four or five of the beasts found fossilized together in the Utah desert did indeed move in unison while alive. And the BLM researchers even think the dinos probably hunted as a unit.

Smithsonian Magazine reported on the finding, which researchers working for BLM Utah outlined in a study recently published in the journal Paleontology and Evolutionary Sciences. BLM paleontologist, Dr. Alan Titus, actually discovered the group of T. rex back in 2014—naming the dig site the Rainbows and Unicorns Quarry. (Indeed, a jumbo pile of T. rex bones is a lucky find.) But researchers have only now assembled evidence from the site that more definitively points to the predators being social carnivores.

The fossil group at Utah’s Grand Staircase-Escalante National Monument, which stands as the first T. rex “mass death state site” in the southern U.S., has been preserved well enough for researchers to conclude that the group of T. rex did indeed live together. And that they likely hunted in packs, similar to wolves.

“Traditional excavation techniques, supplemented by the analysis of rare earth elements, stable isotopes and charcoal concentrations convincingly show a synchronous death event at the Rainbows site of four or five tyrannosaurids,” T. rex expert, Dr. Philip Currie, said in a BLM Utah press release. “Undoubtedly, this group died together, which adds to a growing body of evidence that tyrannosaurids were capable of interacting as gregarious packs,” Currie added.

BLM / Dr. Alan Titus

The researchers say this discovery adds to a body of evidence suggesting T. rex were socially complex. And that the 15,000-pound dinosaurs were, in fact, not just capable of hunting together like wolves, but also interacting in friendly ways; like birds, T. rex‘s closest living relatives.

“This discovery should be the tipping point for reconsidering how these top carnivores behaved and hunted across the northern hemisphere during the Cretaceous,” Dr. Joe Sertich, Curator of Dinosaurs at the Denver Museum of Nature & Science and project contributor, added in BLM Utah’s release. Indeed, T. rex may have cared a lot more about each other than we can imagine. The evidence in this case, for example, suggests a flash flood wiped out the group as they roamed together.

BLM / Alan Titus

The researchers’ goal now is to find even more conclusive evidence these particular T. rex were in a social cohort.  And further bring to light T. rex‘s social behaviors in general. Speaking of which, it’s too bad we can’t put collar cameras on these extinct terrors. Because those tend to provide excellent insight into the bloody private lives of wild predators.