Accessibility/Mobile Features
Skip Navigation
Skip to Content
Editorial News
Lifestyles
Classified Sites

The Canadian Press - ONLINE EDITION

Australian study traces how nature evolved the ancient beasts into birds

This undated artist rendering provided by the journal Science shows the dinosaur lineage which evolved into birds shrank in body size continuously for 50 million years. From left are, the ancestral neotheropod, the ancestral tetanuran, the ancestral coelurosaur, the ancestral paravian and Archaeopteryx. Scientists have mapped how one group of dinosaurs evolved from the likes of the fearsome Tyrannosaurus rex and primitive Herrerasaurus to the welcome robin and cute hummingbird. The surprisingly steady shrinking and elegant evolution of some Triassic dinosaurs is detailed in the journal Science on Thursday. Comparing fossils of 120 different species and 1,500 skeletal features, especially leg bones, researchers constructed a detailed family tree of theropod dinosaurs. That suborder of dinos survives to this day as birds, however unrecognizable and improbable it sounds. (AP Photo/Davide Bonnadonna, Science)

Enlarge Image

This undated artist rendering provided by the journal Science shows the dinosaur lineage which evolved into birds shrank in body size continuously for 50 million years. From left are, the ancestral neotheropod, the ancestral tetanuran, the ancestral coelurosaur, the ancestral paravian and Archaeopteryx. Scientists have mapped how one group of dinosaurs evolved from the likes of the fearsome Tyrannosaurus rex and primitive Herrerasaurus to the welcome robin and cute hummingbird. The surprisingly steady shrinking and elegant evolution of some Triassic dinosaurs is detailed in the journal Science on Thursday. Comparing fossils of 120 different species and 1,500 skeletal features, especially leg bones, researchers constructed a detailed family tree of theropod dinosaurs. That suborder of dinos survives to this day as birds, however unrecognizable and improbable it sounds. (AP Photo/Davide Bonnadonna, Science)

WASHINGTON - Scientists have mapped how a group of fearsome, massive dinosaurs evolved and shrank to the likes of robins and hummingbirds.

Comparing fossils of 120 different species and 1,500 skeletal features, especially thigh bones, researchers constructed a detailed family tree for the class of two-legged meat-eaters called theropods. That suborder of dinos survives to this day as birds, however unrecognizable and improbable it sounds.

The steady downsizing and elegant evolution of the theropods is detailed in the journal Science on Thursday.

"They just kept on shrinking and shrinking and shrinking for about 50 million years," said study author Michael S. Y. Lee of the University of Adelaide in Australia. He called them "shape-shifters."

Lee and colleagues created a dinosaur version of the iconic ape-to-man drawing of human evolution. In this version, the lumbering large dinos shrink, getting more feathery and big-chested, until they are the earliest version of birds.

For a couple decades scientists have linked birds to this family of dinosaurs because they shared hollow bones, wishbones, feathers and other characteristics. But the Lee study gives the best picture of how steady and unusual theropod evolution was. The skeletons of theropods changed four times faster than other types of dinosaurs, the study said.

A few members of that dino family did not shrink, including T. rex, which is more of a distant cousin to birds than a direct ancestor, Lee said.

He said he and colleagues were surprised by just how consistently the theropods shrank over evolutionary time, while other types of dinosaurs showed ups and downs in body size.

The first theropods were large, weighing around 600 pounds (270 kilograms). They roamed about 220 million to 230 million years ago. Then about 200 million years ago, when some of the creatures weighed about 360 pounds (165 kilograms), the shrinking became faster and more prolonged, the study said. In just 25 million years, the beasts were slimmed down to barely 100 pounds. By 167 million years ago, 6-pound (3-kilogram) paravians, more direct ancestor of birds, were around.

And 163 million years ago the first birds, weighing less than two pounds, probably came on the scene, the study said

Paul Sereno, a dinosaur researcher at the University of Chicago who wasn't part of this study, praised Lee's work as innovative.

The steady size reduction shows "something very strange going on," Sereno said. "This is key to what went on at the origin of birds."

People may think bigger is better, but sometimes when it comes to evolution smaller can be better because bigger creatures are more likely to go extinct, Sereno said.

And when the theropods started shrinking there weren't many other small species that would compete with them, Lee said.

"The dinosaur ancestors of birds found a new niche and a new way of life," Lee said.

Sereno added, "When you are small, it's a totally different ball game. You can fly and glide and I think that's what drove it."

___

Online:

The journal Science: http://www.sciencemag.org

___

Seth Borenstein can be followed at http://twitter.com/borenbears

  • Rate this Rate This Star Icon
  • This article has not yet been rated.
  • We want you to tell us what you think of our articles. If the story moves you, compels you to act or tells you something you didn’t know, mark it high. If you thought it was well written, do the same. If it doesn’t meet your standards, mark it accordingly.

    You can also register and/or login to the site and join the conversation by leaving a comment.

    Rate it yourself by rolling over the stars and clicking when you reach your desired rating. We want you to tell us what you think of our articles. If the story moves you, compels you to act or tells you something you didn’t know, mark it high.

Sort by: Newest to Oldest | Oldest to Newest | Most Popular 0 Commentscomment icon

You can comment on most stories on brandonsun.com. You can also agree or disagree with other comments. All you need to do is register and/or login and you can join the conversation and give your feedback.

There are no comments at the moment. Be the first to post a comment below.

Post Your Commentcomment icon

Comment
  • You have characters left

The Brandon Sun does not necessarily endorse any of the views posted. Comments are moderated before publication. By submitting your comment, you agree to our Terms and Conditions. New to commenting? Check out our Frequently Asked Questions.

letters

Make text: Larger | Smaller

Election 2014
Brandon Sun Business Directory
The First World War at 100
Why Not Minot?
Welcome to Winnipeg

Social Media