Being the most ferocious dinosaur, Tyrannosaurus rex once roamed the lands that now encompass North America with impunity. And if the conclusions of a new research project are correct, their behavior could have been even more frightening and intimidating than previously imagined. According to an article published on April 19 in the open access journal PeerJ: Life and the environment Tyrannosaurus rex was most likely not a lone hunter, but worked in packs to run, surround, and greedily consume the animals they depended on for animal feed, just like wolves.
A circular display of Tyrannosaurus rex skulls. ( Kumiko from Tokyo, Japan / CC BY-SA 2.0 )
Tyrannosaurus Rex: The complex truth finally appears
This fascinating and somewhat discouraging discovery came from a study by a team of paleontologists working with the US office in Utah.
Scientists have conducted an extensive analysis of a diverse collection of Tyrannosaurus rex bones found on a fertile Cretaceous fossil site in southern Utah, near the Grand Staircase-Escalante National Monument. This site is colloquially known as the “Rainbow and Unicorn Quarry”, in recognition of all the rare fossils (“unicorns”) that have been unearthed there.
Paleontologist Alan Titus, who discovered the Rainbows and Unicorns site in 2014 and is one of the lead authors of PeerJ study, says the group of dead and fossilized specimens of Tyrannosaurus rex were the victims of a massive flood that drowned them and washed their bodies in a lake. They lay on the bottom, grouped together and undisturbed, for millions of years, until climatic and geological changes dried up the lake and created a river (also now extinct) that eroded the soil and brought the bones back to the surface of the earth. .
“We used a truly multidisciplinary approach (physical and chemical evidence) to share the history of the site together,” said Celina Suarez, a geologist and study participant at the University of Arkansas. “The final result [was] that tyrannosaurs died together during a seasonal flood event. ”
Members of the BLM research team see their findings as providing indirect but clear evidence of the dynamics of the group in action among the Tyrannosaurus rex specimens in question. Their cooperative behavior would have been survival-oriented, centered around group hunting, and probably allow for extensive parental care, scientists postulate.
“The new Utah site adds to the growing body of evidence that tyrannosaurs were complex and large predators, capable of social behaviors common to many of their living relatives, birds,” said research project participant Joe Sertich, who is the curator of 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.”
A family of Tyrannosaurus rex dinosaurs on the run. ( Orlando Florin Rosu / Adobe Stock)
Slowly and surely the race is won
Previous evidence to support the thesis that Tyrannosaurus rex hunted in packs appeared in 2020, when Canadian scientists published the results of their study on the physiology and anatomy of the tyrannosaurus in the May issue of the journal Plus one .
Contrary to previous claims, that Tyrannosaurus rex can travel at speeds of up to 70 kilometers per hour, Canadian researchers have concluded that a sprinting T. rex would not have reached the age of 12 miles per hour (20 miles per hour). kilometers per hour). The anatomy of T. rex would have allowed them to travel at that distance over considerable distances, however, according to McGill University professor Hans Larsson.
“If this were their way of hunting, being able to go much longer distances at a fairly good level [but not great] clip, what kind of lifestyle would that be? The animals that do this today are those, like wolves, that hunt in packs, “Larsson said.
It should also be noted that the bone bed found in southern Utah is not the first Tyrannosaurus rex mass grave discovered on the North American continent. Two decades ago, more than a dozen distinct T. rex fossils were found buried together at a site in Red Deer, Alberta, Canada, and yet another mass burial of T. rex was unearthed several years ago. later in Montana.
If the package hypothesis is true, no doubt awaits more such discoveries.
Tyrannosaurus rex attacks an Einiosaurus. ( Elenarts / Adobe Stock)
Imagining countless packs of T. Rexes starving to hunt
If Tyrannosaurus rex hunted in teams, as more and more evidence suggests, the cohesion of their group would have given them evolutionary advantages that would have been reflected in their population.
During their 2.5 million year reign as king of the dinosaurs, the mighty Tyrannosaurus rex was always the predator and never the prey. Consequently, there would have been little evidence of population growth other than the occasional food shortage (which was probably rare on prehistoric land full of animal life).
Which raises an interesting question: exactly how many specimens of Tyrannosaurus rex lived and died on the North American continent before the whole species disappeared about 65 million years ago?
A team of scientists and science students from the University of California-Berkeley set out to find the answer to this interesting question. They collected all data on Tyrannosaurus rex that were obtained from fossil records and used that information to calculate the average lifespan of T. rex, along with the creature’s nutritional needs and likely reproductive competence.
After shaking all the numbers, the Cal-Berkeley team determined that there were approximately 20,000 individual animals living on 1.4 million square miles (2.3 million square kilometers) of available space at all times. They estimated that a new generation would be born every 19 years and that approximately 127,000 generations of T. rex would have existed during the lifespan of its species of 2.5 million years.
If these estimates are correct and scientists claim that it is 95% certain that they are, it means that 2.5 billion Tyrannosaurus remains lived and died on this planet. If they traveled in groups of 10 to 20, between one and two thousand packets of T. rex would have roamed the continent looking for food at some point.
Assuming that was the case, the animals that T. rex preyed on would have enjoyed some precious moments of peace. As soon as a thundering herd of the most terrifying predator the planet had ever produced passed, another would soon arrive across the horizon, and the new herd would be as greedy as its predecessor.
If human beings ever perfected the science of time travel, we should probably think twice about visiting the North American continent during the late Cretaceous.
Top image: Tyrannosaurus rex, according to the latest scientific study, hunted in packs, just like wolves. Source: warpaintcobra / Adobe Stock
By Nathan Falde