Long-held beliefs about dinosaurs are often revised in light of new findings, from just-discovered fossils to the DNA analysis of old ones. But dislodging old ideas isn’t always easy — especially when they’re popular.
There are plenty of myths about modern animals that are amazingly persistent, despite being regularly debunked. Myths like “camels store water in their humps” (the humps are actually packed full of fat, which is handy fuel for long plods through the desert). Or “bats are blind” (in fact, bats use their vision in tandem with echolocation to catch insects in low light).
But dinosaur myths are even more persistent, and perhaps that’s because no human has ever seen an actual dinosaur. The last one disappeared nearly 66 million years ago, a period of time that’s 825,000 times as long as the average human lifetime. In addition, dinosaurs — especially the giants of the bunch — have a kind of mythic status all their own; they fit seamlessly with human legends and fables featuring dragons, gargoyles, griffins, and other fantastic creatures. And that may be no accident. Both folklorists and scientists have suggested that the fossils of dinosaurs like protoceratops and stegosaurus, perhaps stumbled upon by ancient peoples for thousands of years, may have inspired some of these stories. When a thigh bone the size of a human being or an enormous beaked skull turns up along the path ahead, its finders can only imagine the animal it must have belonged to — a terrifying giant of a creature, with whom one’s ancestors might even have done battle. Here be dragons, indeed.
Despite the legends of the ancient world, we now know that human beings and actual dinosaurs never met in person. The great apes, or hominids, evolved some 6 million years ago, nearly 60 million years after the dinosaurs vanished. And our own hominid group, modern Homo sapiens, was a latecomer, arriving on the scene a mere 200,000 years ago. So all of what we know of these real-life fantastic creatures has come from their fossilized remains — and modern science.
Very large fossils stand out from the crowd, so it’s not surprising that perhaps the longest-standing popular myth about dinosaurs is that they were all gargantuan, the length of a city bus and the height of a construction crane. And some really were, such as the giant sauroposeidon (the dinosaur in the background here), or the largest dinosaur discovered (so far), the colossal Argentinosaurus, who may have weighed more than 106 tons (96.2 metric tons), and whose body, including its tail, measured up to 130 feet (39.6 m) long. The famously ferocious T. rex, by contrast, came in at a mere 9 tons (8.2 metric tons) and 40 feet (12.2 m). Dinosaurs were a diverse, ever-changing group of reptiles in which some iconic species achieved staggering sizes never before — and never since — seen in land animals.
But the fossil record, while incomplete, shows that dinosaurs came in a vast range of sizes, from rabbit- to rhino-sized and up. One of the smallest was microraptor, a birdlike dinosaur with four wings, one on each of its feathered arms and legs. Microraptor weighed just 2 pounds (0.9 kg) and was a bit bigger than a crow. Studies show that it was covered in a mix of glossy black and iridescent feathers. This tiny dinosaur was a carnivore, catching and eating small mammals and birds. It was also a fan of fish.
Microraptor’s coloring might at first seem surprisingly un-dinosaur-like. In the twentieth century, it was widely assumed that dinosaurs wore camouflage colors of gray and brown (like today’s large mammals, such as elephants and rhinos) or muted green. Dinosaurs, however, were reptiles. And modern reptiles come in an astonishing array of colors and patterns. Lizards can be especially gaudy, wearing scaly skin in rainbow hues from neon green to orange, turquoise, pink, and purple, in splotches, zigzags, and intricate, nearly paisley-like patterns. Paleontologists now say that there’s no reason to think that all dinosaurs wore olive drab, but it’s difficult to know what they wore instead, when bones are often the only evidence left behind.
But studies are discovering that some dinosaurs, especially those in the birdlike crowd, may have been more colorful than we ever imagined. In 2010, paleontologists announced that they had examined the fossilized feathers of a dinosaur called sinosauropteryx, a meat-eating theropod like velociraptor and T. rex. There, they found melanosomes (pigment-producing factories) and a surprise: The birdlike sinosauropteryx was likely covered in bristly orange feathers and may even have brandished an orange-and-white striped tail.
While today’s reptiles all have scales, it’s been a subject of debate in paleontology as to whether some familiar dinosaurs long thought to be scaly, such as T. rex, were in fact feathered, like sinosauropteryx. But a 2017 study found evidence that the adult T. rex was likely covered in scales, although a small patch of feathers wouldn’t have been impossible.
Paleontologists think that unlike modern reptiles, dinosaurs weren’t cold-blooded, with their body temperature varying wildly with the temperature of the surrounding air. Dinosaurs grew very quickly, burning energy at a higher rate than the typical modern reptile. This suggests that they may have been warm-blooded, like birds and mammals. Some paleontologists think that dinosaurs may have been mesotherms, without a warm-blooded animal’s set thermostat, but with some degree of temperature control. (Modern mesotherms include, among other species, great white sharks and leatherback turtles.) Average body temperature may have varied by size, with smaller dinosaurs running at a relatively low temperature of, say, around 77°F (25°C). The heavier the dinosaur, the hotter: The enormous sauroposeidon, some think, may have been a toasty-warm 118°F (48°C).
Some dinosaurs may also have been surprisingly attentive parents. While most modern reptiles are famous for abandoning their just-laid eggs, dinosaurs’ closest living relatives, birds, tend their eggs until they hatch and then ferry back food for the hatchlings. Dinosaurs probably got their “bad parent” rap from the misnamed oviraptor (“egg thief”), whose fossil was discovered in a nest full of eggs. Similar fossil finds have proved that the dinosaur was actually in her own nest, perched on her own eggs to keep them warm. Likewise, triceratops seems to have traveled in cozy family groups of adults and juveniles.
And then there’s the idea that dinosaurs were already marked for doom before their relatively rapid extinction — that they were a group of not-very-successful animals that would have disappeared no matter what. Most paleontologists say that dinosaurs were actually extraordinarily successful at adapting to and evolving on an ever-changing Earth. They thrived on this planet for some 180 million years. The familiar dinosaurs we know today from movies, TV, and museum exhibits were finally bested by an intruder from outer space. It’s a scenario that sounds more like the premise of a science fiction movie than what it is: the real story of the end of an epic reign on planet Earth.
Excerpted from Dinosaur: A Photicular Book by Dan Kainen and Kathy Wollard (Workman). Copyright © 2018.