Birds Really Are Dinosaurs, Explained

Archaeopteryx
This is Archaeopteryx, discovered in 1861, and though it's a dinosaur, it resembles a bird. Of course, all birds are now thought to derive from theropod dinosaurs, thus making them dinosaurs themselves. Zhao Chuang / courtesy of Peking Natural Science Organization

Forget what you may have heard: Dinosaurs didn’t all go extinct 65 millions years ago. In fact, dinosaurs are all around us.

As thoroughly explain in a colorful new exhibit which opens March 21 at the American Museum of Natural History in New York—entitled “Dinosaurs Among Us”—birds are the direct descendants of theropod dinosaurs. These creatures were smaller than many other dinos, walked on two feet and many were covered in feathers and likely flew.

This isn’t a new idea. It was first proposed in the 19th century by English biologist Thomas Huxley. But it was promptly ignored for the next 130 years, says Mark Norell, paleontology curator at AMNH. In the past 25 years or so, however, the scientific consensus has turned toward this idea. “What’s new here is that all our modern technology tell us more than we thought we could ever know about the connections between dinosaurs and birds,” Norell says.

Yutyrannus-huali Yutyrannus huali, which means “ beautiful feathered tyrant,” is a relative of T. rex and was covered in a coat of "proto-feathers." It was discovered in northeastern China in 2012. AMNH / R. Mickens

For example, recent work has shown behavioral similarities between birds and dinosaurs. As shown in the exhibit, there is fossil evidence that many theropods laid eggs in nests, and even sat atop them, brooding like modern birds, says museum postdoctoral student Ashley Heers. Heers studies how juvenile birds use their underdeveloped wings, which in some cases look very similar to the wings of their dinosaur ancestors. Other research at the museum has shown similarities between the super-efficient lungs of dinosaurs and birds, and demonstrated that both groups had air-filled pockets in their bones that made them lightweight.  

Birds and theropods also both walked on two legs, and many of each had (or have, for those still walking the earth) three talons on each arm/wing. Each group likewise possess wishbones, bony structures in the chest, Norell says.

Then there are the feathers, which are thought to have evolved from scales, and likely useful for providing shade and cooling, besides also providing insulation, and likely for use as ornamentation during displays (like modern-day peacocks).

Citipati-dinosaur Citipati osmolskae fossils were discovered by scientists from the American Museum of Natural History and the Mongolian Academy of Sciences in 1993 in Mongolia, and they resembled modern ostriches. Zhao Chuang; courtesy of Peking Natural Science Organization

Dominating the center of the exhibit is a feathered specimen of Yutyrannus huali, a cousin to Tyrannosaurus rex. This fearsome predator didn’t fly, but the inclusion of later theropods like Anchiornis huxleyi, which still look very much like dinosaurs but have wings and tail feathers, clearly suggest how the latter evolved to become the former.  

The exhibit goes on to show further similarities between modern species of birds like ostriches and dinosaurs like Citipati (pictured below), as well as the uncanny similarities between the eggs of each group.

After leaving the museum, it’s hard not to look at the most banal of pigeons in a new light. Or the millions of other birds flying around the planet. Today, scientists know of about 13,000 species of birds—2.5 times the number of known mammal species, Norell says. “One could argue that we still live in the age of dinosaurs,” he adds.

Dinosaur-nest The exhibit features a climbable dinosaur nest modeled after a nest likely built by one of the largest oviraptorosaurs ever found, Gigantoraptor. AMNH/D. Finnin