A handful of recent discoveries have changed our understanding of how the T. rex hunted, roamed, and grew

Aylin WoodwardApr 29, 2021, 18:24 IST

A full-grown Tyrannosaurus rex weighed about 6 to 9 tons and stood about 12 to 13 feet high at the hip.Illustration by Zhao Chuang/Courtesy of PNSO

Already in the first few months of 2021, new findings about the Tyrannosaurus rex have shifted paleontologists' picture of how the dinosaur hunted, moved, and grew into a fearsome predator.
Examinations of adult T. rex skeletons have revealed that the animal preferred to walk slowly and couldn't run.
Researchers also determined that the T. rex developed stiff, bone-crushing jaws once it became an adult, after experiencing a huge growth spurt during its teenage years.
The previously held idea that this type of dinosaur preferred a solo lifestyle has also been called into question: A recent fossil finding suggests a pack of Tyrannosaurs died together while hunting.

Reconstructing the behavior of a predator that hasn't walked on the Earth in over 66 million years isn't easy. But the T. rex is such a compelling creature that paleontologists continue to pore over its fossils.

The skeleton of a T. rex named Scotty, which is the largest dinosaur skeleton ever found in Canada. Amanda Kelley

Reconstructing the behavior of a predator that hasn't walked on the Earth in over 66 million years isn't easy. But the T. rex is such a compelling creature that paleontologists continue to pore over its fossils.

In total, 32 adult rex skeletons have made it into public museums worldwide for scientists to study.

A scene from "Jurassic Park." Universal Pictures

For starters, scientists confirmed that T. rexes were so massive, they couldn't run without hurting themselves.

A model of an adult T. rex at the American Museum of Natural History in New York City. D. Finnin/American Museum of Natural History

So the iconic "Jurassic Park" scene in which a T. rex chases down three park visitors driving away in a Jeep wasn't accurate.

A scene from "Jurassic Park." Universal

The T. rex most likely preferred to walk at a leisurely 3 miles per hour - "that's basically the speed at which T. rex would take a stroll," van Bijlert told Insider.

A T. rex skeleton named Stan on display at Christie's Auction House in New York City, September 2020. Spencer Platt/Getty Images

This slow speed likely meant it took a T. rex a while to forage for food, find water, and scout out an area, according to van Bijlert.

The skeleton of T. rex named Trix at Naturalis Biodiversity Center in the Netherlands. Mike Bink

Based on that territory size estimate, a group of scientists from the University of California calculated the total number of adult T. rexes that ever walked the Earth: a whopping 2.5 billion.

A Tyrannosaur skull found two miles north of the "Rainbows and Unicorns Quarry" on February 26, 2019. BLM photo courtesy of Dr. Alan Titus

Based on that territory size estimate, a group of scientists from the University of California calculated the total number of adult T. rexes that ever walked the Earth: a whopping 2.5 billion.

The calculation helped Marshall answer a question that had been gnawing at him: "When I hold a fossil in my hand, I've always said to myself, 'I know this is freakishly rare.' But just how rare is it - one in a million or one in a trillion?"

A T. rex skeleton owned by the US Army Corps of Engineers. US Army Corps of Engineers/Eileen L. Williamson

The calculation helped Marshall answer a question that had been gnawing at him: "When I hold a fossil in my hand, I've always said to myself, 'I know this is freakishly rare.' But just how rare is it - one in a million or one in a trillion?"

If adult T. rexes are an incredibly rare find, fossils from juvenile rexes - which were svelter than their full-grown counterparts - are even rarer.

A model of a 4-year-old T. rex at the American Museum of Natural History in New York City. D. Finnin/American Museum of Natural History

That agile, compact size afforded juveniles certain hunting advantages: Younger rexes could run, and therefore hunt different prey than adult rexes.

An artist's depiction of a juvenile Tyrannosaurus rex as fleet-footed predators with knife-like teeth. Julius T. Csotonyi

Paleontologists had long wondered how a T. rex could bite through solid bone without breaking its own skull. New research offers an answer.

Museum staff from of Naturalis Biodiversity Center unpack Trix the T. rex at Glasgow's Kelvin Hall in Scotland, April 2019. Jeff J Mitchell/Getty Images

These new findings build on other research about the differences between how adult and juvenile T. rexes hunted.

A 4-year-old T. rex illustration. Illustration by Zhao Chuang, courtesy of PNSO

Juvenile and adult rexes differed in looks in addition to size. Young rexes were covered in feathers for warmth and camouflage.

An illustration of a Tyrannosaurus rex with feathers. Illustration by Zhao Chuang/courtesy of PNSO

Other tyrannosaur species were a predatory tour de force, too. Some of the T. rex's cousins may have hunted in packs like wolves.

An illustration of an Albertosaurus. Wikimedia Commons

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A handful of recent discoveries have changed our understanding of how the T. rex hunted, roamed, and grew

Reconstructing the behavior of a predator that hasn't walked on the Earth in over 66 million years isn't easy. But the T. rex is such a compelling creature that paleontologists continue to pore over its fossils.

In total, 32 adult rex skeletons have made it into public museums worldwide for scientists to study.

For starters, scientists confirmed that T. rexes were so massive, they couldn't run without hurting themselves.

So the iconic "Jurassic Park" scene in which a T. rex chases down three park visitors driving away in a Jeep wasn't accurate.

The T. rex most likely preferred to walk at a leisurely 3 miles per hour - "that's basically the speed at which T. rex would take a stroll," van Bijlert told Insider.

This slow speed likely meant it took a T. rex a while to forage for food, find water, and scout out an area, according to van Bijlert.

Based on that territory size estimate, a group of scientists from the University of California calculated the total number of adult T. rexes that ever walked the Earth: a whopping 2.5 billion.

The calculation helped Marshall answer a question that had been gnawing at him: "When I hold a fossil in my hand, I've always said to myself, 'I know this is freakishly rare.' But just how rare is it - one in a million or one in a trillion?"

If adult T. rexes are an incredibly rare find, fossils from juvenile rexes - which were svelter than their full-grown counterparts - are even rarer.

That agile, compact size afforded juveniles certain hunting advantages: Younger rexes could run, and therefore hunt different prey than adult rexes.

Paleontologists had long wondered how a T. rex could bite through solid bone without breaking its own skull. New research offers an answer.

These new findings build on other research about the differences between how adult and juvenile T. rexes hunted.

Juvenile and adult rexes differed in looks in addition to size. Young rexes were covered in feathers for warmth and camouflage.

Other tyrannosaur species were a predatory tour de force, too. Some of the T. rex's cousins may have hunted in packs like wolves.