The world鈥檚 most famous dinosaur, Tyrannosaurus rex, was probably warm-blooded like birds and mammals, new evidence, obtained from 66-million-year-old tooth enamel, suggests, adding weight to previous findings.

at South Carolina State Museum, who wasn鈥檛 involved in the new study, says the research means 鈥渢he opening to the last Jurassic World flick was one big pile of Hollywood bunk鈥�.

鈥淭hat film premised that dinosaurs could not survive in the modern world, except near the equator,鈥� says Persons. 鈥淣ot so. The evidence indicates that a Tyrannosaurus would be comfortable in subtropical and even mild climates.鈥�

at the University of California, Los Angeles, and his colleagues analysed the chemistry in the enamel of three T. rex teeth and compared them with five similarly aged fossilised crocodile teeth.

The researchers also compared their results with data from mammals such as elephants and mammoths to try to determine whether T. rex was also an endotherm 鈥� an animal that can regulate its body heat through its metabolism. Ectothermic, or so-called cold-blooded animals like crocodiles, often warm up by basking in the sun instead.

Endothermy is common in large animals and even some fish, says Eagle, allowing them to move around and exhibit more sustained activity to find food and migrate, and to live in colder environments. It has long been thought that many dinosaurs, including T. rex, were also warm-blooded.

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鈥淚t comes at a cost though 鈥� higher metabolic rates mean higher food requirements and potentially more active hunting to acquire it,鈥� he says.

Within the enamel chemistry, the researchers focused on the abundance of bonds between rare heavy isotopes of carbon and oxygen, known as carbon-13-oxygen-18 bonds. These bonds are more abundant in minerals that form at cold temperatures than minerals that form at warm temperatures.

鈥淭herefore, in a very old tooth we can measure carbon-13-oxygen-18 bond abundance and figure out whether it formed in a hot or cold body.鈥�

He says T. rex had a body temperature of around 36掳C, similar to large modern mammals but below many modern birds.

鈥淲e also found that the reconstructed temperature of T. rex was significantly elevated compared to temperatures derived from crocodile teeth from the same geological formation 鈥� Hell Creek in Montana,鈥� Eagle says.

The researchers also say that T. rex body temperatures were higher than the ambient temperatures in prehistoric Montana, reconstructed both from isotopic estimates and climate models.

鈥淯sing thermal performance curves and climate modelling based on these results, we found that the entire North American continent would have been habitable for T. rex in the Cretaceous Period,鈥� he says.

The shocking fossils that show T. rex wasn鈥檛 the king of the dinosaurs

We鈥檝e always thought that Tyrannosaurus rex was an unchallenged apex predator during the dying days of the dinosaurs. But a fresh look at controversial fossils has prompted palaeontology鈥檚 biggest-ever U-turn

Persons says there was already extensive evidence that T. rex was warm-blooded, including bone growth rates and predator-prey ratios 鈥� with energy-hungry endotherms than ectotherms 鈥� and a 鈥渟lew of anatomical traits consistent with high-performance athleticism鈥�.

at Carthage College in Wisconsin says the new work is an 鈥渆xample of science in action, converging upon a single, robust hypothesis, which in this case reveals T. rex as an active top predator鈥�.

The researchers 鈥渕ake the case for a wide geographic distribution for T. rex, showing that it could tolerate cool temperatures in the north of its range and tolerate the tropical temperatures in the south鈥�, says Carr. 鈥淎nd in both cases, T. rex鈥榮 body temperature is higher than the average air temperature. That result is consistent with the hypothesis that T. rex might have migrated from Asia into North America at high latitudes.鈥�

A bird that was eaten and partially excreted by a dinosaur 66 million years ago has left behind the best-preserved feathers ever recovered by scientists from dinosaur-age rock. This pushes the聽evolution聽of feathers, like the ones on modern birds, back by 10 million years and may tell us more about why most birds didn鈥檛 survive the post-asteroid mass extinction.

鈥淭his is the best feather we鈥檝e ever seen in a Mesozoic [252 million to 66 million years ago] deposit,鈥� says at the Field Museum in Chicago. 鈥淸It鈥檚] like a feather you could pick up off the ground.鈥�

Birds were the only dinosaurs to survive the mass extinction triggered by an asteroid strike 66 million years ago. But, puzzlingly, only one branch made it through: neornithes, the ancestors of every bird alive today.

In 2016, at the University of Washington in Seattle was collecting fish fossils in north-eastern Montana鈥檚 Hell Creek Formation when he discovered a broken coprolite, a fossilised dropping, with a feather clearly visible along its fractured surface. 鈥淚 couldn鈥檛 believe what I was seeing,鈥� he says.

A few years later, he invited O鈥機onnor to team up with him and his colleagues to analyse the coprolite using micro-CT scans and 3D surface scanning. Two leg-bone fragments, 18 and 12 millimetres long, resembled some previously found at Hell Creek and attributed to hesperornithiformes. These were flightless, short-winged diving birds, similar to modern loons (Gaviiformes) or grebes (Podicipediformes), and were related to Neornithes.

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Further analyses showed that the 9.3-millimetre-long primary feather had a water-repellent structure, similar to that of modern pelicans, says O鈥機onnor. Both this and a second, smaller wing feather also had lightweight, spongy cores surrounded by a harder outer layer. This combination makes them both light and stiff, which is typical of modern feathers.

鈥淲hat is exciting is to push the occurrence of modern feathers into non-modern birds,鈥� says O鈥機onnor. Differences in plumage are emerging as a major contributing factor as to why some birds survived while others didn鈥檛, she says.

The team also found two fluffy body feathers with loosely arranged branches, echoing in a lineage that didn鈥檛 survive the extinction event.

Combined, this suggests that the bird the feather belonged to 鈥� and hesperornithiformes in general 鈥� had a 鈥渕iddle ground鈥� of primitive and modern plumage, says O鈥機onnor. While the wing and tail feathers might have allowed for successful diving, for example, the less advanced body feathers would have been relatively poor insulators, making the animals more vulnerable to the 鈥渨inter鈥� that occurred after the asteroid impact.

鈥淭hese are the feathers that are responsible for keeping the body warm, right?鈥� says O鈥機onnor. 鈥淪o maybe these primitive feathers were good enough to keep them warm during the greenhouse world of the Mesozoic, but not good enough to keep them warm during this environmental catastrophe that was triggered by this impact event.鈥�

Dinosaur hunting in the Gobi desert: Mongolia

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The dropping 鈥� which probably came from a Nanotyrannus or a young Tyrannosaurus rex 鈥� also contained two rigid, diamond-shaped scales, 3 to 4 millimetres long. The researchers think this came from a gar (Lepisosteidae), a narrow-bodied fish that still exists today. This would have been too small for the dinosaur predator and thus was probably eaten by the bird.

鈥淭his discovery is really exciting,鈥� says at the University of Connecticut. 鈥淚t opens up so many questions about how feathers evolved, what they were originally used for, and how they came to perform so many different functions in modern birds.鈥�

The links among the different animals involved are also fascinating, says Muzio. 鈥淒iscoveries like this really make the imagination run wild,鈥� he says. 鈥淔rom a single coprolite, we are learning about at least three individual species 鈥� morphologically, ecologically and evolutionarily. What more can you ask for?鈥�

Dinosaurs are the biggest creatures to have ever walked on land, dominating Earth for over 130 million years. But how could such extraordinary creatures have simply vanished in the blink of a geological eye? For decades, we’ve assumed these prehistoric megafauna 鈥� a staple of our childhoods and Hollywood movies 鈥� went extinct for one simple reason: the asteroid that hit Earth was so unimaginably large that it changed everything in one single blow. But now, thanks to new research, an even more intriguing idea has emerged: size alone doesn’t explain what happened.

The real reason the impact was so devastating may have been its angle. Had the asteroid arrived a little steeper, the outcome might have been different. A little shallower, different again. And for life on Earth at the time, predominantly dinosaurs on land, marine creatures in the sea and pterosaurs in the air, it appears to have struck at almost the worst possible angle imaginable, launching vast quantities of rock, dust and climate-altering gases high into the atmosphere and triggering one of the greatest mass extinctions in Earth’s history.

With jaws like these, who needs big arms? A new analysis suggests dinosaurs like Tyrannosaurus rex had shrunken forelimbs because their massive, powerful heads became their primary tool for killing large prey, rendering their arms redundant. It is an evolutionary approach that five different lineages of large theropod dinosaurs took independently.

Researchers are well aware that a number of large, predatory theropods followed a trend towards bigger bodies, bigger heads and smaller, shorter arms over time. But it wasn鈥檛 known why this pattern repeated across multiple predatory dinosaur families, scattered across the globe and separated by many millions of years, says at University College London. There was also little understanding of how the bones in their ever-heftier skulls changed as their arms became proportionally smaller.

鈥淭his paper tackles one of the big evolutionary questions in theropod dinosaurs,鈥� says at the University of Bristol, UK, who wasn鈥檛 involved with the research.

Scherer and his colleagues compiled data on the proportions of the forelimbs and skulls of 85 theropod species, along with body-mass data. This allowed them to calculate a ratio between the skull dimensions and forelimb lengths, quantifying just how small the arms were compared with the head. The researchers then compared this ratio with other measurements of the dinosaurs鈥� bodies, along with a measure of the skulls鈥� strength based on factors such as bite force and skull rigidity.

The team found that skull durability was associated with smaller arms, regardless of where the species sat in the theropod evolutionary tree. 鈥淚f it鈥檚 a predatory theropod and has a very robust skull, it will most likely have relatively small forelimbs,鈥� says Scherer.

The researchers found this head-arm divergence evolved independently in five theropod groups: tyrannosaurids, the short-snouted abelisaurids, the knife-toothed carcharodontosaurids, ceratosaurids and megalosaurids. This evolutionary pattern hadn鈥檛 been identified in the last two groups until this study, points out at the Beipiao Pterosaur Museum of China, who wasn鈥檛 involved in the research. This shows how hidden evolutionary signals can be revealed when traits are quantified in this way, she says.

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The findings provide clues as to why the dinosaurs鈥� arms kept shrinking. These predators鈥� increasing skull strength and body size coincided with the rising mass of their quarries. The theropods evolved huge, sturdy skulls for subduing their large, difficult-to-control prey. Their heads were clearly doing the majority of the work, says Scherer, reducing the need for strong, grappling arms.

鈥淣ature doesn鈥檛 like to have everything all at once,鈥� he says. A big, powerful head plus strong forelimbs would require a lot of energy to maintain.

This creates a trade-off between jaws and claws. Other theropods like the megaraptorans and spinosaurs were also very large predators, but they took the opposite route to dinosaurs like T. rex, coupling聽long arms with slender skulls.

Rowe is curious about the mechanical function of the jaw-centric theropods鈥� arms, even in their shortened state. 鈥淵es, tyrannosaurs had tiny, vestigial arms, but that does not necessarily mean they were completely useless,鈥� he says.

He adds that the study emphasises the evolutionary diversity of dinosaurs. 鈥淚t reminds me of why I fell in love with dinosaurs in the first place,鈥� he says. 鈥淭hey were some of the most innovative and successful animals to ever exist.鈥�

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HOW could we talk about David Attenborough鈥檚 best documentaries without featuring the photo perhaps most associated with the broadcaster, whose 100th birthday is on 8 May?

Life on Earth, the groundbreaking 1979 series containing that iconic gorilla sequence, pictured above, introduced a wider audience to the calm narration and stunning nature shots for which Attenborough is known today. His many documentaries would go on to move from the ocean depths to the lives of plants, and from the distant past to the fight against climate change.

Read on to discover which made the biggest impact on our staff, and which they deem worth watching today.

(1979)

Life on Earth is special to me for so many reasons. There is that famous encounter with gorillas. It was also the first ambitious nature series of its kind 鈥� without its success, we might never have had the many great series that followed it. Then there鈥檚 the brilliant way Attenborough tells the story of deep time as he descends the Grand Canyon, and then back up again. There鈥檚 probably as much science here as in the rest of his programmes put together 鈥� I don鈥檛 think I鈥檝e seen a better TV series on the evolution of life. OK, from today鈥檚 perspective it is a bit lectury at times, but who would you rather be lectured by?

Last but not least, for me, it has personal meaning, as I鈥檓 sure it does for many other people who saw it in their youth and were influenced by it. That wonky opening music by Edward Williams is just so evocative.

Michael Le Page, reporter

(1995)

Plants live on another plane of existence. Every morning, drooping wood anemones lift their heads and nod at the sun, while brambles grapple across the forest floor with slow aggression. Exploding pods launch seeds in a millisecond; on mountain tops, bristlecone pines gnarl into stumps over thousands of years.

Time-lapse and high-speed photography weren鈥檛 new when The Private Life of Plants was filmed, but this was the first series to use them at scale. They allowed Attenborough to explore the agency and the intelligence of flora like never before.

When I rewatch the series today, the lurid colour grade, bespoke plant-themed typeface and rudimentary CGI bring me as much joy as the plants鈥� private lives. I would also recommend the behind-the-scenes for the plants of Life, which lays bare the painstaking ingenuity of the film-makers who capture these other worlds.

Thomas Lewton, features editor

(2001)

As the first in-depth look at what is happening beneath the rarely explored waves, The Blue Planet astounded me when I first watched it. New species were discovered and extraordinary footage showed blue whales from the air, alien-looking creatures in the ocean depths and, most surprisingly, herring sperm as far as the eye could see.

I am still haunted 25 years later by watching a pod of orcas spend 6 hours hunting a grey whale calf to eat only its lower jaw and tongue. Attenborough鈥檚 narration is calm, clear and concise, unafraid to let the images and music hold our attention.

It may not have the glossy HD footage or drone shots of more recent series, but it changed the shape of nature documentaries.

It also blew my mind and sparked a life-long interest in the oceans. Without it, I wouldn鈥檛 have ended up at New 女生小视频!

Eleanor Parsons, magazine editor

(2006)

Those nighttime images of a massive pride of lions swarming over a fleeing young elephant have stayed with me ever since the first series was shown in 2006. The film-makers set out to create a spectacular, high-definition series, and boy did they achieve it.

The many notable moments in Planet Earth include a starving polar bear trying to catch walruses, eagles preying on cranes as they fly over the Himalayas, dolphins beaching themselves to hunt fish and bears climbing mountains to feast on moths. This is simply incredible television. Watch it now if you haven鈥檛 seen it. Watch it again if you have.

The second series, first shown in 2016, also made a notable departure. While Attenborough鈥檚 previous series all showed wildlife in pristine wildernesses, the last episode here, and in the third series (2023), is about animals living alongside people, from leopards and monkeys to falcons and otters.

I do think Attenborough has been right to aim to evoke wonder rather than despair in most of his programmes, but now there鈥檚 no denying we live on a much-changed planet.

Michael Le Page, reporter

(2011)

Wondrous and strange is the life that thrives at the very ends of Earth. Frozen Planet cast a loving eye over the inhabitants of the Arctic and Antarctica, hostile lands whose charms are apparent from the earliest moments of this excellent series. The narrative bounces back and forth from one pole to the other, treating us to scheming penguins, swimming snails, polar bears and a bison charging down wolves.

Among it all, the then 84-year-old David Attenborough, bundled up in a fetching array of parkas, makes the odd appearance as our all-terrain guide to these alien environments.

Casting a pall over proceedings, of course, were the advancing effects of climate change. The series鈥� seventh episode, 鈥淥n Thin Ice鈥�, was an explicit call for the world to do more to protect these magnificent ecosystems and those living in them, including humans.

The magic of Frozen Planet wasn鈥檛 just that it told us how global warming imperils the poles, it鈥檚 that it made us truly care about what we might be losing.

Bethan Ackerley, subeditor

(2020)

Like an ice core or tree ring, David Attenborough鈥檚 long and extraordinary life has come to be used as a yardstick for change. Socially, technologically and environmentally, the world of his youth was a far cry from the one we see today 鈥� and in this powerful film, Attenborough charts how we have degraded Earth鈥檚 ecosystems over his lifetime.

Released during the first year of the covid-19 pandemic, A Life on Our Planet was a timely warning from a man who has seen more of Earth鈥檚 wonders 鈥� like this turtle, pictured swimming over a coral reef 鈥� than perhaps anyone else alive. Its marriage of the personal and the political makes it a different beast from most Attenborough films. Climate change, biodiversity loss and rampant pollution all feature, as Attenborough sets out what a child born in 2020 may witness over their lifetime. It makes for bleak viewing, but, as is a hallmark of more recent Attenborough works, it also supplies plenty of solutions to the environmental crises we鈥檙e living through 鈥� if we鈥檇 only apply them.

Bethan Ackerley, subeditor

(2022)

Prehistoric Planet is far from the first programme to try to bring long-extinct animals back to life on the small screen, but it is the best so far. Of course, the programme-makers had to use their imagination to some extent, but the series has been praised by palaeontologists for its accuracy and naturalism.

The three series feature many of the most iconic animals of the past, but shows them in new ways 鈥� we see Tyrannosaurus rex swimming and mating, for instance. There are lots of smaller, lesser-known animals, too. For me, the real stars are not the dinosaurs but the pterosaurs, brought back to life in stunning detail.

The third series jumps forward in time to the recent glacial periods, featuring animals such as mammoths, sabre-toothed cats and many more. The content is just as brilliant, but Tom Hiddleston replaces David Attenborough as the narrator. It鈥檚 just not the same without him.

Michael Le Page, reporter

(2026)

This very late entry to the David Attenborough canon became an instant classic in my household, since it was shown on New Year鈥檚 Day. We鈥檝e rewatched the extraordinary exploits of London鈥檚 wildlife many times.

Yes, this one-off urban showcase has the foxes and pigeons you would expect, but not as you would expect to see them: vixens viciously squaring off on the streets of Tottenham and pigeons intelligently commuting on the tube from Hammersmith are standout moments.

But the bigger surprises come from how much the city鈥檚 nature has changed in recent decades. Peregrine falcons now soar over the centre, ring-necked parakeets have conquered the parks, Aesculapian snakes dangle from the trees along the Regent鈥檚 Canal and, since covid lockdowns, large numbers of fallow deer have taken to roaming parts of Romford.

The programme tours a London that is familiar to locals but rarely seen on screen: the community gardens, cemeteries and suburban parks that make the city an outstanding place to live, even for the nature-lovers who sometimes wonder if a megacity is the right place for them.

Perhaps their lingering doubt will be extinguished by Attenborough鈥檚 own assertion that he wouldn鈥檛 want to live anywhere else.

Penny Sarchet, managing editor

Birds today have dinosaur DNA. They have dinosaur blood in their veins. Birds evolved directly from Velociraptor-type animals and are the only true dinosaurs that still exist. Steve Brusatte is a palaeontologist at the University of Edinburgh, UK, and has been studying 150 million years’ worth of bird evolution, from surviving the asteroid that wiped out their contemporaries to today鈥檚 adaptation into almost every niche. Brusatte introduces elephant birds, terror birds, demon ducks and penguins the size of gorillas, and why “when gulls dive bomb you and try to steal your pasty or your chips鈥�, says Brusatte, “you really can sense in the nastiness, the cunning, the agility, the feistiness. You can sense that inner Velociraptor.鈥�

Read more: The evolving science of dinosaurs

Dinosaurs ruled the Earth for over 165 million years and even now, we鈥檙e still uncovering new secrets about these extraordinary animals.
In this marathon, we explore the latest discoveries in paleontology, and examine where Hollywood gets dinosaurs wrong 鈥� and where it gets them surprisingly right. The truth is, real dinosaurs were often even more remarkable than their blockbuster portrayals, and our understanding of them is evolving all the time.