A remarkable fossil site in Utah, where several tyrannosaurs were found buried together, reinforces a growing theory that these scary creatures hunted in packs, like wolves.
The fact that tyrannosaurs have been social hunters is a possibility that paleontologists have been considering for more than 20 years.. In 1910, paleontologists working in Alberta, Canada, discovered the remains of 12 tyrannosaurs that appeared to have died. together. This discovery was largely forgotten until Canadian paleontologist Philip Currie, now with the University of Alberta, revised the old discovery in 1998, arguing that it was evidence of “gregarious behavior” in tyrannosaurs and that these animals were pack hunters.
Seven years later, Currie, along with several colleagues, reported on a similar discovery made in Montana, in which the remains of three tyrannosaurs, belonging to the genus Daspletosaurus, were also found together. And in 2014, paleontologists described Fossilized dino fingerprints found in British Columbia, Canada, which appeared to show three tyrannosaurs moving in the same direction at the same time.
Despite this evidence, scientists have been reluctant to attribute gregarious behavior to tyrannosaurs, arguing that the dinosaurs’ limited cognitive abilities could not have allowed this. Critics of this theory will now have to consider a third mass death place, as described in a new paper published in PeerJ.
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The fossil site is located inside the Grand Scara-Escalante National Monument and produced the remains of four, possibly five tyrannosaurs, all of whom appeared to have died. at the same time. The fossils were buried at the site of a former river, with the authors of the new paper saying their deaths were likely the result of seasonal flooding.
“The new Utah site adds to the growing body of evidence that tyrannosaurs were complex, large predators capable of common social behaviors in many of their living relatives, birds,” said Joe Sertich, co-author of the paper and curator of dinosaurs at the Denver Museum of Nature and Science, explained in a Press release. “This discovery should be the tipping point for reconsidering how these top carnivores behaved and hunted in the northern hemisphere during the Cretaceous.”
Currie, who was not involved in the new study, said the discovery “adds to a growing body of evidence that tyrannosaurids were able to interact as gregarious packets,” as quoted in the press release. land management in Utah..
The bones of these dinosaurs were found buried at the end of the Campanian era. The Kaiparowits Formation in southern Utah, named after the wonderful nickname, “Rainbows and Unicorns Quarry”. Co-author of the study, Alan Titus of Land management office discovered the site in 2014 and is the first mass-dead tyrannosaurus to be found in the southern United States.
Titus and his colleagues discovered the remains of several Teratofon, a genus of tyrannosaurus that lived in the Cretaceous about 77 million 76 million years ago. This genus is known from only one species, Teratophoneus curriei, of which the largest members measured somewhere between 21 and 26 feet (6.4 and 7.9 meters) in length. Tyrannosaurs or tyrannosaurs describe a family of oversized carnivorous dinosaurs that stood on two legs, the most famous examples being Tyrannosaurus rex, Albertosaurus, Daspletosaurus, and Tarbosaurus.
Besides Teratofon fossils, Titus and his colleagues discovered several turtles, various species of fish and rays, an almost complete skeleton 12 feet long (3.7-meter) Deinosuc alligator and two other species of dinosaurs (none of these animals are believed to have died if they killed Teratofon copies). In addition to these bones, scientists have collected fragments of small rocks and sand deposits from the former Cretaceous river.
“We immediately realized that this site could be used to test the idea of a social tyrannosaurus. Unfortunately, the ancient history of the site is complicated “, said Titus. “With bones that seem to have been exhumed and buried by the action of a river, the original context in which they were was destroyed. However, not everything was lost. ”
Indeed, both the chemical and physical evidence recovered from the site allowed the team to make sense of this ancient scene, despite the geological disturbances mentioned above. The analysis of stable isotopes of carbon and oxygen, together with the concentrations of rare earth elements, gave “a relatively homogeneous signature”, as paleontologists wrote in their work. This strongly suggests that the fossils were all derived from the same source population and that the animals died and fossilized together. It also suggests that no other animals were introduced to the burial site at a later date.
Scientists suspect that a seasonal flood killed the tyrannosaurs, washing their bodies in a nearby lake, where they were eventually buried. The team entertained several other possibilities to explain mass deaths, including poisoning (e.g., drinking water contaminated with cyanobacteria), drought, fire, and even drowning in quicksand. Of these scenarios, the flood is considered the most plausible explanation, according to scientists.
The discovery of the Rainbows and Unicorns career is obviously a big problem, as it is a potential proof for not only cooperative hunting among tyrannosaurs. but sociality in general, which could also be applied to other areas, namely extended parental care. That being said, not everyone is convinced by the new evidence.
“It’s a little harder to be so sure that this data means that these tyrannosaurs lived together in the good old days,” said Kristi Curry Rogers, a biology professor at Macalester College. Associated Press. “It is possible that these animals lived in the same vicinity without traveling together in a social group and gathered around dwindling resources as times became more difficult.”
Fair enough. Just because these dino bodies were buried together doesn’t automatically mean they took part in pack hunting. As Rogers suggests, Teratofon dinosaurs may have gathered together to celebrate with a fallen animal, which may or may not be a typical behavior for these theropods. Eagles, for example, come down to a regular meal, but these birds can hardly be described as pack hunters.
Consequently, further lines of evidence will be needed to support this hypothesis, in particular evidence that these animals were willingly with each other. and that they did so in a cooperative manner. It will not be easy to prove, but no one has said that paleontology is easy.
More: Dinosaurs like it T. rex they were more tyrants than we realized, research suggests.