How Did Dinosaurs Become Birds?

Illustration for article titled How Did Dinosaurs Become Birds?

Most paleontologists agree that birds are living dinosaurs, the distant evolutionary descendants of animals like Tyrannosaurus rex. Less clear, however, is how dinosaurs evolved into the birds we know today.

Advertisement
Advertisement

Above: The claw of a Harpy Eagle, a modern day dinosaur.

Audubon is currently running a feature by Michael Balter about the enigmatic evolutionary history of modern birds, and the researchers working to uncover its mysteries. Evolutionary biologist Ashley Heers, for example, studies the biomechanics of late-date birds to see if their movement at early stages of development bears any resemblance to that of their distant ancestors:

She is using the latest video and computer modeling technology to study how baby birds develop the ability to fly, looking for clues as to how dinosaurs evolved into birds—one of the most dramatic and successful evolutionary transformations in the history of life on earth.

"Every time I look at a bird, I am seeing a dinosaur," she says. "That's what makes it exciting for me

Heers came to England fresh from doing a Ph.D. with Kenneth Dial at the University of Montana's Flight Laboratory in Missoula, Montana, probably the world's leading research center on bird aeronautics. In the course of her research, she has piled up considerable evidence that baby birds do indeed resemble the avian dinosaur ancestors, which had feathers but little if any ability to fly. Thus at nine days old, her downy guinea fowl chicks have very small wings and shafts of primitive-looking feathers still pervious to the air. Their tufts are simple and symmetrical, lacking the complex structure of adult feathers, and the birds are too young to fly very far.

Heers takes one of the chicks out of the cardboard box and places it on an inclined pedestal about a foot away. The chick hesitates a second, then gathers up its wings, and its courage, and jumps back into the box. The video footage, captured on the computer, shows that while the chick relied mostly on its legs to make the leap, it also flapped its wings between two and three times, adding just enough lift to successfully bridge the gap. "They can't yet fly very far," Heers says, "but those tiny little wings are still very useful." This strongly suggests, she adds, that even if early dinos evolved feathers for other reasons—to keep warm or for peacock-like sexual displays—they were already on their way to becoming birds.

Just how bird-like were dinosaurs? How dinosaur-like are modern birds? of modern birds, and the researchers and biomechanics researchers. She is using the latest video and computer modeling technology to study how baby birds develop the ability to fly, looking for clues as to how dinosaurs evolved into birds—one of the most dramatic and successful evolutionary transformations in the history of life on earth.

In her doctoral thesis, Heers drew comparisons between the developmental biology of modern birds and the evolutionary stages of dinosaurs that, over millions of years, developed the capacity for powered flight. The observation was initially met with harsh criticism, but, over the last few years, Heers's and Dials's work has won them "respect and credibility, especially from leading paleontologists:

University of California-Berkeley researcher Kevin Padian, long a fan of Dial's and Heers's work, says the initial skepticism was totally off base: "This was exactly what was needed."

[Stephen Brusatte, a paleontologist at the University of Edinburgh in the United Kingdom and a rising star in the paleontology world] adds, "Their work has been groundbreaking. They are studying living birds, and don't just speculate based on fossils." As for Heers, he says, "She's brilliant. She's not a traditional paleontologist but a real ornithologist."

Advertisement

This is such a fun and compelling read. It's as much an evolutionary backgrounder as it is a profile of interesting paleontologists, most of whom are basically rockstars, anyhow. Go read the rest of the Audubon piece for yourself.

Share This Story

Get our newsletter

DISCUSSION

So which one is it? Did the dinosaurs turn into bird or did they all die do to a asteroid are volcanoes? Last time I check evolution states that it take 10,ooo to 100,000 years or more for a animal to do that type of change, and I really don't think it took that long the for asteroid or volcano to kill them so something is not adding up here there for both could not be true.

this all way to much speculation. for something that should have fossilized evidences on a scale that is no where to be found. Yes you have one or two bones in some dinosaurs that match to one are two bone that birds have but guess what I have one or two bones that match what a dog has does that mean I came from a dog? No it does not! So please come back when you can trace said change of one dinosaur all the though the Ice age and into today's times with full skeletons of said animal trans forming into some bird of today. However you will not be able to do so because it did not happen!

and Please don't try to changing the meaning of evolution. That does not mean to bring up micro evolution which does happen. What does not happen is what is talk about above!

In simple terms, a k9 stays k9, a feline stays a feline, a bird stays a bird and dinosaur stays dinosaur. and a k9 does not go in a feline and a feline does not go into a bird and a dinosaurs or dead not a birds. when you look at a bird you see a bird not a dinosaur. my 3 year old nephew hops like a kangaroo does that mean human are related to kangaroo. we all know the answer to that one. I mean really comparing a baby bird to an adult dinosaur one that has not learned anything and the other that has learned every it will need to live. of course the baby bird had to jump back into the box it had not learned how to fly yet, and this lady has a ph-d that just scary!