What we got wrong about dinosaurs

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Dinosaurs survived and thrived for 165 million years, much longer than the roughly 300,000 years modern humans have traveled on the planet so far.

They lived on every continent, munching on plants, breaking their jaws at insects, itching from fleas, suffering from illnesses, fighting, sleeping, performing elaborate courtship rituals, and caring for their young. The creatures were much more diverse – and downright bizarre – than what we might remember from childhood books.

Scientists have discovered more in the past two decades than in the previous 200 years about the behavior and evolution of dinosaurs. Here’s what’s new and different about what we know about dinosaurs.

How many dinosaurs were there?

The short answer: a lot.

Take T. Rex, the banana-sized predator, perhaps the best-studied dinosaur. Scientists believe that each generation of T. rex numbered 20,000 individuals, representing a total of 2.5 billion over the 2.4 million years they would have lived.

While this is only an estimate and relies on many assumptions, it’s a good reminder that the fossil record captures only a tiny fraction of ancient life. The same team of researchers claim that for 80 million adult T. rex there is only one clearly identifiable specimen in a museum.

Scientists have definitively identified around 900 species of dinosaurs – although there are many other potential species for which paleontologists either do not have enough bones or the fossils are not well enough preserved to truly label them as such. And there are around 50 new dinosaurs discovered each year, inspiring many scientists to believe that we are living in a golden age of paleontology.

Many, many more species existed – one estimate suggests there were between 50,000 and 500,000, but we may never find their fossil remains.

So many species could exist because they were highly specialized, meaning that different types of dinosaurs had different food sources and could live in the same habitats without competing. For example, with unusually large eyes and hair-triggered hearing, Shuuvia deserti, a small desert dinosaur evolved to hunt at night, while Mononykus had puzzled stunted forelimbs, each having only one only functional finger and claw – possibly for eating ants or termites.

It’s worth pointing out, of course, that many of the dinosaurs you may know did not live together in one community. Stegosaurus and T. rex never coexisted, separated by 80 million years of evolution. In fact, the time between Stegosaurus and Tyrannosaurus is greater than the time between T. rex and you.

What do they look like?

The earliest dinosaur discoveries, the oldest over 150 years ago, focused on the sensational: the large bones and skulls we know in museum atriums.

But dinosaurs came in all shapes and sizes. In fact, some of the most exciting discoveries of recent years have been tiny. In 2016, a tail belonging to a creature the size of a sparrow that could have been dancing in the palm of your hand was found preserved in three dimensions in a piece of amber.

New evidence has radically changed the way researchers see and perceive dinosaurs. While some dinosaurs had scaly reptilian skin, many did not and looked much more like birds.

In 1996, a fossil unearthed in China’s Liaoning Province by a farmer digging a well shook the world of paleontology. It preserved brown, furry stuff along the Sinosauropteryx’s head, back, and tail, as the fossilized creature has become known. Paleontologists have described them as primitive feathers, which has sparked intense debate. But it is now widely believed that many dinosaurs had fur or feathers.

Since then, according to Xu Xing, a paleontologist at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing who worked on some of the earliest feathered fossils, 50 species of feathered dinosaurs have been found, mainly – but by no means exclusively – in one of the three main lineages of dinosaurs: therapods.

Therapods are two-legged dinosaurs that include familiar predators like velociraptors and T. Rex, which most likely had some sort of feather. While many feathered dinosaurs were small, some, like Yutyrannus, were tall: The 30-foot-long dinosaur was covered in wispy feathers. (We are not sure if all of the therapy was feathered.)

“Different feathers tell us different things about dinosaurs. Many dinosaurs use feathers to isolate themselves, some dinosaurs use feathers to display themselves, others use feathers to fly,” Xu said.

The first feathered fossil Xu studied was the Beipiaosaurus, which was discovered in 1997 and was for some time the largest known feathered dinosaur. He said when he first saw it he knew immediately that it would be the biggest find of his career.

Thanks to these findings, scientists now believe that the birds that flutter in our backyards evolved directly from small theropod dinosaurs.

They probably acquired bird-like characteristics piece by piece, shrinking, losing their sharp teeth and evolving beaks and the ability to fly over time. Their small size and ability to fly may have helped them survive the city-sized asteroid that hit the coast of Mexico 66 million years ago and doomed most dinosaurs to extinction.

Change of outfit?

Feathers aren’t just an outfit change that popular cultural depictions of dinosaurs simply haven’t succeeded in making. They can reveal intriguing details about the coloring of dinosaurs – something once thought impossible to know – and the habitats in which they lived.

In some fossils, tiny structures called melanosomes that once contained pigments are preserved. By comparing melansomas with those of living birds, scientists can determine the possible original colors of the feathers. In the case of Sinosauropteryx, the dark areas of the fossil were a rusty brown or ginger color, and the rest were considered white.

“If you have a black feather, the melanosomes are shaped like little sausages. Then if you have red or reddish-brown hair, they obviously have a slightly different chemical makeup. They are shaped like meatballs,” he said. Jakob Vinther, a senior. senior lecturer in paleobiology and evolutionary biology at the University of Bristol in the United Kingdom.

On the left are the "meat balls" shaped melansomas - structures that correspond to ginger or reddish-brown pigment. On the right are

“And whether you take the breast of a European robin or the hair of a redhead, (melansomas) are shaped like meatballs,” he added.

In 2017, Vinther and his colleagues also found evidence of cover-up in Sinosauropteryx: a dark back and light underside, a striped tail, and a band of “bandit mask” running through its eyes. They believe he lived in an open habitat like a savannah because the animals living in these environments exhibit marked contrasts in their body markings.

Similar research on other dinosaurs revealed that they were surprisingly colorful: Microraptor, a bizarre dinosaur with four wings, for example, had a bright, iridescent sheen in its feathers, while Psittacosaurus had a dark back and a larger belly. clear, but the contrast between the different colors suggested that he lived in a closed habitat like a forest.

So why is there so much resistance to the idea of feathered, fluffy dinosaurs? Vinther blames the legacy of the “Jurassic Park” film franchise and its portrayal of fierce reptilian killers.

“‘Jurassic Park’ was a milestone. The story (is) so captivating and exciting. You can’t play with ‘Jurassic Park.’ “

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