T-REX HAD FEATHERS?
At first glance, it may be hard to see how the ducks you feed, the pigeons you dodge, or the peacocks you admire have anything in common with the “terrible lizards” portrayed in iconic dinosaur movies such as Jurassic Park.
But many scientists now believe that modern birds are living dinosaurs. Specifically, a group of two-legged carnivorous dinosaurs called theropods seems to have evaded the great dino extinction event 65 million years ago by developing feathers, bigger and more adaptable brains, and smaller, more airborne forms.
“It’s important that people understand dinosaurs are still among us,” says Mark Norell, chair of paleontology at the American Museum of Natural History in New York. “They’re represented by at least 13,000 species alive today.”
Norell has curated the new exhibit Dinosaurs Among Us, which opened in March 2016, that maps out the evolutionary history of birds while challenging the popular perception of dinosaurs as green, scaly lizards.
Following the latest evidence, all the dinosaurs on display are covered in feathers.
THE EVOLVING PICTURE
In scientific circles, the idea that birds are living dinosaurs isn’t new. As early as the 1800s, Reverend Edward Hitchcock, the state geologist of Massachusetts, and Thomas Huxley, an English biologist, both independently noted that dinosaur footprints and bones were very bird-like. But their observations were largely overlooked until John Ostrom of Yale University resurrected the similarities between birds and theropod dinosaurs nearly a century later.
Ostrom studied a fossil creature from the end of the Jurassic period called Archaeopteryx, a raven-sized dinosaur that had wings and flight feathers. He found that the bird-like animal shared skeletal characteristics with theropods—sharp teeth, three-clawed fingers, and a long bony tail.
Since then, thousands of feathered dinosaurs have been discovered, many of which seem to be branches in the bird family tree. And in 1996, scientists in China unearthed Sinosauropteryx, the first feathered theropod that isn’t a direct relative of birds. These discoveries are helping scientists not only piece together the origin of modern avians, but also to re-write long-held notions about the ways many dinosaurs looked and behaved.
For instance, the largest known feathered dinosaur, a 23-foot-long tyrannosaur that lived 125 million years ago known as Yutyrannus huali, changes the popular image of its most iconic relative.
“One of the most important things about the Yutyrannus is that we can infer from it that the Tyrannosaurus rex must also have had feathers,” says Norell. While these larger dinosaurs couldn’t fly, they likely used their primitive plumage for insulation or visual displays, the same way modern peacocks attract mates. And fossil evidence shows that feathered dinosaurs probably came in a rainbow of colors.
“If we can have pink flamingos, we could have pink feathered dinosaurs as well,” says Jack Horner, curator of paleontology at the Museum of the Rockies.
Various fossils show how feathers evolved from primitive filament structures to more complex, aerodynamic forms, as well as how wings evolved in stages, according to Ashley Heers, a postdoctoral researcher in the American Museum of Natural History’s paleontology division.
“Flight is actually the most physically challenging form of locomotion,” says Heers. Before true flight evolved, early wings might have been used to slow aerial descents, she says. Small wings could have also provided a boost when leaping out of reach of predators or pouncing on prey, or they might have helped dinosaurs run up steep slopes.
Aside from feathers, researchers have found dinosaurs that display a host of other bird-like traits. Recent CT scans of the insides of dinosaur skulls, for example, show that the parts of the brain that control sight, flight, and high-level memory functions were every bit as expanded in theropods as they are in living birds. And researchers have found small predators called Citipati protecting their nests of eggs, as well as large Allosaurus with the same hollow bone structures that make birds light enough to fly.
“It used to be that people thought of fish, amphibians, reptiles, birds, and mammals as completely distinct groups of animals with no overlap,” says Horner. “Now, when we look across the board at all the animal groups, dinosaurs and birds have more in common than either birds or dinosaurs have in common with any other animal.”
Despite all this scientific consensus, pop culture might take a while to acknowledge the evolution of feathered dinosaurs, says Robert Bakker, curator of paleontology at the Houston Museum of Natural Science and one of the advisors for the 1993 film Jurassic Park. It’s simply easier, and perhaps scarier, to have scaly green dinosaurs, he says.
“That’s something we’re all waiting for — a Jurassic Park where there’s no more naked dinosaurs.”
By Knvul Sheikh
PUBLISHED APRIL 5, 2016