Study: 2.5 billion T. rex roamed Earth, but not all at once
FILE - In this Tuesday, March 7, 2006 file photo, life-sized Tyrannosaurus rex models are unloaded for a dinosaur exhibition in Potsdam, Germany. A study released on Thursday, April 15, 2021 calculates that 2.5 billion Tyrannosaurus rex prowled North America over a couple million years or so, with maybe 20,000 at any given time. (AP Photo/Sven Kaestner)
One Tyrannosaurus rex seems scary enough. Now picture 2.5 billion of them. That’s how many of the fierce dinosaur king probably roamed Earth over the course of a couple million years, a new study finds.
Using calculations based on body size, sexual maturity and the creatures’ energy needs, a team at the University of California, Berkeley figured out just how many T. rex lived over 127,000 generations, according to a study in Thursday’s journal Science. It’s a first-of-its-kind number, but just an estimate with a margin of error that is the size of a T. rex.
“That’s a lot of jaws,” said study lead author Charles Marshall, director of the University of California Museum of Paleontology. “That’s a lot of teeth. That’s a lot of claws.”
The species roamed North America for about 1.2 million to 3.6 million years, meaning the T. rex population density was small at any one moment. There would be about two in a place the size of the Washington, D.C., or 3,800 in California, the study said.
“Probably like a lot of people, I literally did a double-take to make sure that my eyes hadn’t deceived me when I first read that 2.5 billion T. rexes have ever lived,” said Macalester College paleobiologist Kristi Curry Rogers, who wasn’t part of the study.
Marshall said the estimate helps scientists figure the preservation rate of T. rex fossils and underscores how lucky the world is to know about them at all. About 100 or so T. rex fossils have been found — 32 of them with enough material to figure they are adults. If there were 2.5 million T. rex instead of 2.5 billion, we would probably have never known they existed, he said.
Marshall’s team calculated the population by using a general biology rule of thumb that says the bigger the animal, the less dense its population. Then they added estimates of how much energy the carnivorous T. rex needed to stay alive — somewhere between a Komodo dragon and a lion. The more energy required, the less dense the population. They also factored in that the T. rex reached sexual maturity somewhere around 14 to 17 years old and lived at most 28 years.
Given uncertainties in the creatures’ generation length, range and how long they roamed, the Berkeley team said the total population could be as little as 140 million or as much as 42 billion with 2.4 billion as the middle value.
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The science about the biggest land-living carnivores of all time is important, “but the truth, as I see it, is that this kind of thing is just very cool,” said Purdue University geology professor James Farlow.
'Like nothing seen in nature before': strange dinosaur has scientists enthralled
The highly unusual Ubirajara jubatus boasted a mane of ‘hair-like structions’ and two ‘ribbon-like features’, researchers say
About 110 million years ago along the shores of an ancient lagoon in what is now north-eastern Brazil, a two-legged, chicken-sized Cretaceous period dinosaur made a living hunting insects and perhaps small vertebrates like frogs and lizards.
On the inside, it was ordinary, with a skeleton similar to many small dinosaurs from the preceding Jurassic Period, scientists said on Tuesday. On the outside, it was anything but.
This dinosaur, called Ubirajara jubatus, possessed a mane of hair-like structures while also boasting two utterly unique, stiff, ribbon-like features probably made of keratin – the same substance that makes up hair and fingernails – protruding from its shoulders.
“There are plenty of other strange dinosaurs, but this one is unlike any of them,” said David Martill, a paleobiology professor at the University of Portsmouth in England, who helped lead the study, published in the journal Cretaceous Research.
Ubirajara’s hair-like structures appear to be a rudimentary form of feathers called protofeathers. This was not actual hair, an exclusively mammalian feature. Many dinosaurs had feathers. In fact, birds evolved from small feathered dinosaurs about 150m years ago.
“Likely from a distance it looked hairy rather than feathery,” Martill said. “Likely it had hair-like protofeathers over much of its body but they are only preserved along its neck, back and arms. The ones on its back are very long and give it a sort of mane that is unique for dinosaurs.“
Ubirajara’s ribbon-like structures may have been used for display, possibly to attract mates or intimidate adversaries or in inter-male rivalry, Martill added. Such displays often are made by male animals – think of a peacock’s elaborate tail feathers – leading Martill to make an “educated guess” that this Ubirajara individual was male.
“The ribbons that seem to come from the shoulders are like nothing I have seen in nature before,” Martill said.
While it is impossible to know from the fossil – which arrived at a museum in Ceará state in the early 1990s, ScienceNews reported – Martill said Ubirajara may have been colorful.
“I bet it was,” he added.
The 10 coolest dinosaur findings of 2020
The newly described "reaper of death" is a cousin of Tyrannosaurus rex. (Image credit: Julius Csotonyi)
Dinosaurs went extinct 66 million years ago, but we're still learning their secrets. Here are 10 mind-blowing dino discoveries, including newly described species, an analysis of soft-shelled dinosaur eggs and takedowns of speculative species.
1. Spinosaurus could swim
Two Spinosaurus hunt Onchopristis, a prehistoric sawfish, in the waters of the Kem Kem river system in what is now Morocco. (Image credit: Jason Treat, NG Staff, and Mesa Schumacher Art: Davide Bonadonna Source: Dr. Nizar Ibrahim, University of Detroit Mercy)
Scientists thought for years that Spinosaurus could swim, but had precious few fossils to prove it. The most complete specimen had been destroyed in an Allied bombing raid against Germany during World War II. But now, the analysis of a Spinosaurus tail reveals that the tail was broad and paddle-like, perfect for a swimmer, according to an April study in the journal Nature.
"This discovery is the nail in the coffin for the idea that non-avian dinosaurs never invaded the aquatic realm," study lead author Nizar Ibrahim, a paleontologist at the University of Detroit Mercy, said in a statement. "This dinosaur was actively pursuing prey in the water column, not just standing in shallow waters waiting for fish to swim by."
2. Best-preserved dino stomach
The nodosaur Borealopelta markmitchelli preferred to munch on a particular type of fern, an analysis of its fossilized stomach contents reveals. (Image credit: Illustration by Julius Csotonyi/Copyright Royal Tyrrell Museum of Palaeontology )
It's challenging to know exactly what herbivorous dinosaurs ate — leaves and other plant materials don't fossilize well, and even if ancient organic matter is preserved, it's hard to know whether the dinosaur ate it, or if the two fossilized side-by-side by chance.
The discovery of a nodosaur fossil with a well-preserved digestive tract has helped shed light on this mystery. Researchers analyzed the 112 million-year-old beast's fossilized stomach contents, and learned that the nodosaur, named Borealopelta markmitchelli, was a picky eater, according to the June study in the journal Royal Society Open Science.
The 18-foot-long (5.5 meters) B. markmitchelli ate only certain types of ferns, and apparently it preferred leaves to stems and twigs. The dinosaur also had pea- to grape-size stones, known as gastroliths, in its gut that likely helped it break down food.
Bon appetit!
3. Horned titanosaur embryo
The 1.2-inch-long baby dinosaur skull (Image credit: Kundrát M. et al. Current Biology (2020); Illustration by Vladimir Rimbala )
Before the long-necked titanosaur dinosaurs got huge, they were wee babes with … a horn?
The discovery of a rare titanosaur embryo in Argentina revealed that this little tyke had a rhino-like horn on its snout, which it lost by adulthood, an August study in the journal Current Biology found.
No word yet on whether its enormous parents thought this little babe's horn looked cute 80 million years ago, but at least the horn was handy — it's possible the baby used it to peck out of its shell.
4. Soft-shelled eggs
A clutch of fossilized Protoceratops eggs, which were found in the Gobi Desert of Mongolia at Ukhaa Tolgod. (Image credit: M. Ellison/©AMNH)
Speaking of eggs, the first dinosaur eggs may have had soft shells, a June study in the journal Nature found. Researchers found ancient eggs from two dinosaur species — the horned dinosaur Protoceratops, which lived during the Cretaceous period, and the long-necked sauropodomorph Mussaurus that lived during the Triassic period.
In a separate Nature study, another group of scientists in Antarctica found the 68 million-year-old soft-shell egg of a mosasaur, which is not a dinosaur but a reptilian sea monster that lived during the dinosaur age.
It's still a mystery whether this football-size mosasaur egg was laid and hatched in the water, or on dry land like a turtle.
5. Meet T. rex's cousin: 'Reaper of death'
Researchers have only two skulls from this new species, but here is what the dinosaur may have looked like nearly 80 million years ago. (Image credit: Julius Csotonyi)
Tyrannosaurus rex has a newfound cousin with a fearsome name — the "reaper of death," which hails from what is now Alberta, Canada. This 79.5 million-year-old beast (Thanatotheristes degrootorum) is the oldest named tyrannosaur on record from North America. It's also the first newly named tyrannosaur from Canada in 50 years. (Congrats, Canada!)
"It definitely would have been quite an imposing animal, roughly 8 feet (2.4 meters) [tall] at the hips," Jared Voris, a doctoral student of paleontology at the University of Calgary in Alberta and lead researcher of the study, told Live Science in February.
The "reaper of death" had unique vertical ridges that ran from its eyes along its upper snout. Scientists aren't sure why the carnivore had these ridges, but if you were its prey, they were possibly one of the last things you saw before the reaper finished you off.
6. The dinosaur that wasn't
This 99 million-year-old creature's skull is preserved in amber. (Image credit: Lida Xing)
A 99 million-year-old piece of amber from Myanmar (formerly Burma) with a mystery creature's skull preserved inside made headlines when researchers said it might be the smallest dinosaur on record. This bird-like dinosaur was said to have about 100 sharp and tiny teeth and weigh just 0.07 ounces (2 grams), the weight of two dollars bills.
However, other specimens of this animal have now been analyzed further, and it appears that it's not a dinosaur, but a lizard. As a result, the original study was retracted.
Even so, the researchers of the retracted study are still excited to celebrate this weird beastie. "It's just a really weird animal and an important discovery regardless of whether it's a weird bird or a weird lizard with a bird head," study co-lead researcher Jingmai O'Connor, formerly a senior professor of vertebrate paleontology at the Chinese Academy of Sciences, who is now at the Field Museum of Natural History in Chicago, told Live Science in July.
7. Tyrannosaur embryos
Researchers have found a toe claw (shown in yellow, second from left) and jawbone (shown in blue, third from left) of baby tyrannosaurs that lived between 75 million and 70 million years ago in North America. For scale, here are reconstructions of the tyrannosaur babies compared with an adult Albertosaurus tyrannosaur (left) and lead researcher Gregory Funston. (Image credit: Gregory Funston 2020)
The only two tyrannosaur embryos on record are now being studied, and gosh are they small. This apex predator started out with a skull the size of a mouse.
The fossils of these wee babes include a toe claw found in Alberta, Canada and a jawbone unearthed in Montana.
"These are incredibly rare finds — the first of their kind in the world," lead researcher Gregory Funston, a paleontologist at the University of Edinburgh in Scotland, told Live Science in October. "Juvenile tyrannosaurs of any kind are exceedingly rare, and we've never found any bones that we suspected might be embryos, until now."
8. Two knocks against Nanotyrannus
Teenage T. rex were more lightly built and faster than the much larger, lumbering, bone-crushing adults they would grow into. (Image credit: Julius T. Csotonyi)
Does the species Nanotyrannus exist? Some researchers say certain tyrannosaur remains belong to a pygmy tyrannosaurus called Nanotyrannus, while others maintain the remains are teenage Tyrannosaurus rexes. The majority of researchers often say Nanotyrannus hasn't been completely ruled out, so until more evidence piles up, it's possible the beast was real.
Unfortunately for Nanotyrannus, 2020 brought two studies saying it was a teenage rex. In a January study in the journal Science Advances, researchers studied two well-known tyrannosaurus specimens, nicknamed Jane and Petey. A bone analysis found that Jane and Petey were just 13 and 15 years old, and that their bones were growing quickly, just like a teenager's would.
The second study, published in June in the journal PeerJ, took an intense look at 44 different T. rex individuals and analyzed the species' growth stages. The teenage T. rexes fit perfectly into the growth curves, indicating that Nanotyrannus is a T. rex, not a separate species.
9. Dueling Dinosaurs sold to museum
This illustration shows what may have happened to the ceratopsian and tyrannosaur just before they died and were fossilized about 67 million years ago. (Image credit: Anthony Hutchings/Friends of the North Carolina Museum of Natural Sciences)
Two famous dinosaur fossils are finally being studied by scientists. The so-called "Dueling Dinosaurs," the fossils of the most complete Tyrannosaurus rex and Triceratops on record, which may (or may not) have been dueling at the time of their deaths, are going to the North Carolina Museum of Natural Sciences (NCMNS) following a $6 million deal in November.
Amateaur fossil hunters in Montana discovered the "Dueling Dinosaurs" in 2006, but couldn't find a buyer. The fossils also failed to sell at a 2013 auction. And then, a lawsuit dogged the discovery, with the land's previous owners claiming the fossils were theirs.
But now, the 67 million-year-old Dueling Dinosaurs are getting an extraordinary exhibit that will invite the public and students to get involved as scientists slowly learn about the dinosaurs encased in stone.
10. Could duck-billed dinosaurs swim?
Duckbill dinosaurs evolved in North America, spreading to South America, Asia, Europe and finally Africa. (Image credit: Raul Martin)
A newly discovered duck-billed dinosaur named Ajnabia odysseus was found where it shouldn't have been. Its fossils were unearthed in Morocco, a November study found. "It was completely out of place, like finding a kangaroo in Scotland," study lead researcher Nicholas Longrich, a paleontologist at the University of Bath, said in a statement.
Duck bills evolved in North America and later made their way to South America, Asia and Europe. But Africa was an island continent 66 million years ago during the late Cretaceous, when A. odysseus was alive. So, how did it get there?
Did the pony-size A. odysseus raft to Africa on debris? Did it float or possibly swim there? Your guess is as good as ours!
