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

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

Reconstructing the habits of a predator that hasn’t walked on the Earth in over 66 million years is not simple. But the T. rex is such a compelling creature that paleontologists proceed to pore over its fossils.

Scotty T. rex

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

When the T. rex starred in Steven Spielberg’s blockbuster “Jurassic Park” in 1993, solely seven or eight T. rexes had been uncovered. The very first was found in 1902.

But in the 25 years since the film got here out, scientists have discovered dozens extra T. rex skeletons, and that has helped sharpen our understanding of how these animals hunted and moved.

In complete, 32 grownup rex skeletons have made it into public museums worldwide for scientists to review.

jurassic park sprinkler shot

A scene from “Jurassic Park.” Universal Pictures

Already in the first 4 months of 2021, a handful of discoveries have additional confirmed the methods through which the T. rex in “Jurassic Park” did not resemble its real-life counterpart.

For starters, scientists confirmed that T. rexes have been so large, they could not run with out hurting themselves.

t rex

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

A absolutely grown T. rex is one of the largest carnivorous land animals to ever stroll the Earth, standing about 12 to 13 ft tall at the hip and measuring as much as 43 ft from tooth to tail. An grownup may weigh between 5.5 and 9 tons.

But that dimension brings sure drawbacks: A bone can solely deal with a lot stress whereas working earlier than it breaks. One study discovered that if a T. rex moved any quicker than 12 mph, the predator’s bones would have shattered.

So the iconic “Jurassic Park” scene through which a T. rex chases down three park guests driving away in a Jeep wasn’t correct.

jurassic park

A scene from “Jurassic Park.” Universal

In reality, the T. rex most popular to stroll slowly, in response to a study published last week that reconstructed the animals’ tails to calculate a T. rex’s pure step rhythm.

You may in all probability out-walk a T. rex, or at the very least sustain with one, in response to Pasha van Bijlert, a paleobiomechanics professional who co-authored that examine.

The T. rex more than likely most popular to stroll at a leisurely three miles per hour – “that’s basically the speed at which T. rex would take a stroll,” van Bijlert advised Insider.

t rex skeleton stan christies

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

That’s slightly below the average preferred walking speed for a human.

This sluggish velocity possible meant it took a T. rex some time to forage for meals, discover water, and scout out an space, in response to van Bijlert.


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

Another study printed this month calculated {that a} single grownup T. rex lived in an space roughly 40 sq. miles in dimension.

That means a territory the dimension of Manhattan or San Francisco would have been essential to maintain only one grownup rex. Surveying an space that enormous may have taken a T. rex greater than 13 hours.

Based on that territory dimension estimate, a bunch of scientists from the University of California calculated the complete quantity of grownup T. rexes that ever walked the Earth: a whopping 2.5 billion.

T. Rex

The researchers discovered that about 20,000 grownup T. rexes may have been alive at any given time in the species’ existence.

“The total number did catch me off guard,” Charles Marshall, a paleontologist at the University of California, Berkeley, who co-authored the analysis, previously told Insider.

By taking a look at the common time span between when rexes turned absolutely grown and after they died in their early 30s, Marshall calculated that about 127,000 generations of T. rexes may have lived on Earth. Multiply that quantity by 20,000 per technology, and you wind up with 2.5 billion adult T. rexes that lived and died on Earth roughly 66 to 68 million years in the past.

The calculation helped Marshall reply a query 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?”

Army Corps of Engineers T rex dinosaur fossil

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

His recent evaluation means that the T. rex skeletons found to date characterize only one in each 80 million grownup rexes that ever roamed the planet — a paltry 0.00000125%.

If grownup T. rexes are an extremely uncommon discover, fossils from juvenile rexes – which have been svelter than their full-grown counterparts – are even rarer.

juvenile t. rex

A mannequin 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

It took a T. rex 20 years to develop from a tiny hatchling to a 9-ton predator with tooth that might crush bone. Most of that progress occurred between the ages of 14 and 18, when the dinosaur’s physique dimension doubled.

A juvenile rex was so small relative to an grownup that when paleontologists first discovered a pair juvenile skeletons, they thought the fossils belonged to a different pygmy T. rex species.

That agile, compact dimension afforded juveniles sure searching benefits: Younger rexes may run, and subsequently hunt completely different prey than grownup rexes.


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

A juvenile rex hunted quicker, smaller prey, partly as a result of it did not have had the energy of an grownup’s chunk.

An grownup rex had a bite force of 7,800 pounds, which may crush a car. No different identified animal in historical past may chunk with such power. That’s why full-grown T. rexes may hunt big prey like triceratops or duck-billed dinosaurs.

Younger rexes had serrated, knife-like tooth as an alternative.

Paleontologists had lengthy puzzled how a T. rex may chunk by way of strong bone with out breaking its personal cranium. New analysis provides a solution.

Dinosaur bones

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

That research, introduced earlier this month, discovered that the T. rex had specialised bones that helped to stiffen its decrease jaw when it bit down. A paper printed in March confirmed that the dinosaur’s stiff decrease jaw solely developed as soon as a T. rex completed its teenage progress spurt and turned a completely grown grownup.

Mostly possible, the T. rex had a rigid skull like these of modern-day crocodiles and hyenas, relatively than a versatile one like birds and reptiles. That’s how the dinosaur may bite down on its prey with the weight of about three Mini Coopers.

These new findings construct on different analysis about the variations between how grownup and juvenile T. rexes hunted.

Juvenile t rex

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

Because rexes’ our bodies, motion, and tooth changed a lot as they grew up, youthful and older rexes did not have to compete for prey.

Prior to their progress spurts, juvenile T. rexes may transfer quicker than adults as a result of they have been extra evenly constructed. If a grown T. rex wished to pursue prey, it may solely transfer at speeds between 10 and 25 mph for temporary stints.

“They go through a drastic change when they grow up, from these sleek, slender, fleet-footed T. rexes with these wonderful knife-like teeth to these big, monster, plodding, crushing tyrannosaurs that we are familiar with,” Scott Williams, a paleontologist from New York University who co-authored a study about this, told Insider last year.

Juvenile and grownup rexes differed in appears to be like along with dimension. Young rexes have been coated in feathers for heat and camouflage.

T. rex

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

An grownup T. rex, on the different hand, rocked a mullet of feathers on its head, neck, and tail, in response to paleontologists from the American Museum of Natural History.

Still, Williams mentioned, “these animals probably dominated their ecosystems at all ages.”

Other tyrannosaur species have been a predatory tour de power, too. Some of the T. rex’s cousins could have hunted in packs like wolves.


Paleontologists just lately found a handful of tyrannosaur skeletons in Utah’s Grand Staircase-Escalante National Monument. These aren’t T. rexes: The tyrannosaur class consists of comparable two-legged carnivores like Albertosaurus and Gorgosaurus as nicely.

A recent study about the fossil discovering suggests {that a} pack of dinosaurs all died at the identical time, maybe whereas searching collectively — which might imply not all tyrannosaurs were solitary predators in the method specialists thought. Instead, some could have been social animals that labored collectively, like modern-day birds.

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