News / Science & Technology

Dinosaur Descendants Shrank to Survive

Tyrannosaurus rex went extinct in a relatively short compared to the dinosaur line that led to birds. (Credit: Royal Ontario Museum)
Tyrannosaurus rex went extinct in a relatively short compared to the dinosaur line that led to birds. (Credit: Royal Ontario Museum)
Rosanne Skirble
Not all dinosaurs went extinct. Some are alive today in the form of birds. A new study finds that shrinking helped these birds continue to thrive and evolve.  

“If we really want to know how birds came about, then we need to study the line leading to birds, which includes this big diversity of animals like triceratops and stegosaurus and T. Rex,” said Roger Benson, associate professor of paleontology at Oxford University and lead author of the study reported PLOS Biology.

His team followed the evolution more than 400 dinosaurs, noting their size and what they weighed.  

“The largest dinosaur in our study we believed weighed 90 tons, and the smallest dinosaur was a bird called Qiliania and that weighed 15 grams," Benson said. "So you could fit Qiliania six million times inside Argentinosaurus, the largest dinosaur.”
 
Dinosaur Descendants Shrank to Survive
Dinosaur Descendants Shrank to Survive i
|| 0:00:00
...
 
🔇
X

Since these species are extinct, Benson's team calculated that weight with an analysis of fossil limbs which, like pillars, would hold up the weight of the dinosaur.

“And there’s a welcome strained relationship between the robustness of those pillars and the mass of the animal that is observed among modern mammals and reptiles, and so it’s fairly reliable for knowing the masses of extinct animals,” he said.
The lightweight Archaeopteryx is considered the first bird. Its shrinking size might have been key to the evolutionary success of birds. (Credit: Roger Benson)The lightweight Archaeopteryx is considered the first bird. Its shrinking size might have been key to the evolutionary success of birds. (Credit: Roger Benson)
x
The lightweight Archaeopteryx is considered the first bird. Its shrinking size might have been key to the evolutionary success of birds. (Credit: Roger Benson)
The lightweight Archaeopteryx is considered the first bird. Its shrinking size might have been key to the evolutionary success of birds. (Credit: Roger Benson)


The study examined how fast body size changed on the entire family tree of dinosaurs, based on the thickness of their thigh bones. It found dinosaurs quickly evolved big bodies, soon after their origins about 220 million years ago.

Then the rates of growth slowed and these giants went extinct after 20 million years. Benson says the one exception was the line leading to birds, which kept evolving a range of body mass, including radically smaller body sizes.

“We find that fast rates of evolution are maintained for the whole study period, so for nearly 200 million years," Benson said. "So this is a very evolvable lineage. There’s a long ancient background to the modern radiation [spread] of birds through which their ancestors were constantly finding new ecological opportunities and inventing new ways of being an organism.”

He says the long journey evident in the fossil record that connects the 10,000 bird species alive today underscores a bigger evolutionary question.

“We're no longer asking how the radiation of living birds proceeded over, let's say, 100 million years," he said. "Instead we're asking where does biological diversity come from over very long time scales and ultimately those time scales might be relevant in establishing how life evolved in general, not just birds or just even vertebrates, but just organisms or animals in general?”  

Benson says what is clear from this study is that evolving different sizes was important to the success of the feathered dinosaur lineage. His next step is to look at other patterns in dinosaur evolution to see how other features changed over time.

You May Like

Turkey's Controversial Reform Bill Giving Investors Jitters

Homeland security reform bill will give police new powers in search, seizure, detention and arrests, while restricting the rights of suspects, their attorneys More

Audio Slideshow In Kenyan Prison, Good Grades Are Path to Freedom

Some inmates who get high marks could see their sentences commuted to non-custodial status More

'Rumble in the Jungle' at 40

'The Champ' knocked Foreman out to regain crown he had lost 7 years earlier when US government accused him of draft-dodging and boxing officials revoked his license More

This forum has been closed.
Comments
     
There are no comments in this forum. Be first and add one

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Victorious Secularists Face Challenge to Form Government in Tunisiai
X
Henry Ridgwell
October 30, 2014 11:39 PM
Official results from Tunisia show the Islamist Ennahda party has failed to win the second free election since the so-called "Arab Spring" uprising in 2011. Ennahda, which handed power to a government of technocrats pending the elections, lost out to the secular party Nidaa Tounes. Henry Ridgwell reports from London that the relatively peaceful poll offers some hope in a volatile region.
Video

Video Victorious Secularists Face Challenge to Form Government in Tunisia

Official results from Tunisia show the Islamist Ennahda party has failed to win the second free election since the so-called "Arab Spring" uprising in 2011. Ennahda, which handed power to a government of technocrats pending the elections, lost out to the secular party Nidaa Tounes. Henry Ridgwell reports from London that the relatively peaceful poll offers some hope in a volatile region.
Video

Video Africa Tells its Story Through Fashion

In Africa, Fashion Week is a riot of colors, shapes, patterns and fabrics - against the backdrop of its ongoing struggle between nature and its fast-growing urban edge. How do these ideas translate into needle and thread? VOA’s Anita Powell visited this year’s Mercedes Benz Fashion Week Africa in Johannesburg to find out.
Video

Video Smugglers Offer Cheap Passage From Turkey to Syria

Smugglers in Turkey offer a relatively cheap passage across the border into Syria. Ankara has stepped up efforts to stem the flow of foreign fighters who want to join Islamic State militants fighting for control of the Syrian border city of Kobani. But porous borders and border guards who can be bribed make illegal border crossings quite easy. Zlatica Hoke has more.
Video

Video China Political Meeting Seeks to Improve Rule of Law

China’s communist leaders will host a top level political meeting this week, called the Fourth Plenum, and for the first time in the party’s history, rule of law will be a key item on the agenda. Analysts and Chinese media reports say the meetings could see the approval of long-awaited measures aimed at giving courts more independence and include steps to enhance an already aggressive and high-reaching anti-corruption drive. VOA’s Bill Ide has more from Beijing.
Video

Video After Decades of Pressure, Luxembourg Drops Bank Secrecy Rules

European Union finance ministers have reached a breakthrough agreement that will make it more difficult for tax cheats to hide their money. The new legislation, which had been blocked for years by countries with a reputation as tax havens, was approved last week after Luxembourg and Austria agreed to lift their vetoes. But as Mil Arcega reports, it doesn’t mean tax cheats have run out of places to keep their money hidden.
Video

Video Kobani Refugees Welcome, Turkey Criticizes, US Airdrop

Residents of Kobani in northern Syria have welcomed the airdrop of weapons, ammunition and medicine to Kurdish militia who are resisting the seizure of their city by Islamic State militants. The Turkish government, however, has criticized the operation. VOA’s Scott Bobb reports from southeastern Turkey, across the border from Kobani.

All About America

AppleAndroid