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: No Ransom Paid for Release of Hostages Held by IS Militants

President Erdogan hails release of hostages as diplomatic success but declines to be drawn on whether their release freed Ankara's hand to take more active stance against insurgents More

Audio Sierra Leone Ends Ebola Lockdown

Health ministry says it has reached 75 percent of its target of visiting 1.5 million homes to locate infected, educate population about virus More

US Pivot to Asia Demands Delicate Balancing Act

As tumult in Middle East distracts Obama administration, efforts to shift American focus eastward appear threatened 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.
Natural Gas Export Plan Divides Maryland Towni
X
Deborah Block
September 21, 2014 2:12 PM
A U.S. power company that has been importing natural gas now wants to export it. If approved, its plant in Lusby, Maryland, would likely be the first terminal on the United States East Coast to export liquefied natural gas from American pipelines. While some residents welcome the move because it will create jobs, others oppose it, saying the expansion could be a safety and environmental hazard. VOA’s Deborah Block examines the controversy.
Video

Video Natural Gas Export Plan Divides Maryland Town

A U.S. power company that has been importing natural gas now wants to export it. If approved, its plant in Lusby, Maryland, would likely be the first terminal on the United States East Coast to export liquefied natural gas from American pipelines. While some residents welcome the move because it will create jobs, others oppose it, saying the expansion could be a safety and environmental hazard. VOA’s Deborah Block examines the controversy.
Video

Video Difficult Tactical Battle Ahead Against IS Militants in Syria

The U.S. president has ordered the military to intensify its fight against the Islamic State, including in Syria. But how does the military conduct air strikes in a country that is not a U.S. ally? VOA correspondent Carla Babb reports from the Pentagon.
Video

Video Iran, World Powers Seek Progress in Nuclear Talks

Iran and the five permanent members of the U.N. Security Council plus Germany, known as the P5 + 1, have started a new round of talks on Iran's nuclear program. VOA State Department correspondent Pam Dockins reports that as the negotiations take place in New York, a U.S. envoy is questioning Iran's commitment to peaceful nuclear activity.
Video

Video Alibaba Shares Soar in First Day of Trading

China's biggest online retailer hit the market Friday -- with its share price soaring on the New York Stock Exchange. The shares were priced at $68, but trading stalled at the opening, as sellers held onto their shares, waiting for buyers to bid up the price. More on the world's biggest initial public offering from VOA’s Bernard Shusman in New York.
Video

Video Obama Goes to UN With Islamic State, Ebola on Agenda

President Obama goes to the United Nations General Assembly to rally nations to support a coalition against Islamic State militants in Iraq and Syria. He also will look for nations to back his plan to fight the Ebola virus in West Africa. As VOA White House correspondent Luis Ramirez reports, Obama’s efforts reflect new moves by the U.S. administration to take a leading role in addressing world crises.
Video

Video Migrants Caught in No-Man's Land Called Calais

The deaths of hundreds of migrants in the Mediterranean this week has only recast the spotlight on the perils of reaching Europe. And for those forunate enough to reach a place like Calais, France, only find that their problems aren't over. Lisa Bryant has the story.
Video

Video Westgate Siege Anniversary Brings Back Painful Memories

One year after it happened, the survivors of the terror attack on Nairobi's Westgate Shopping Mall still cannot shake the images of that tragic incident. For VOA, Mohammed Yusuf tells the story of victims still waiting for the answer to the question 'how could this happen?'
Video

Video Militant Assault in Syria Displaces Thousands of Kurds

A major assault by Islamic State militants on Kurds in Syria has sent a wave of new refugees to the Turkish border, where they were stopped by Turkish border security. Turkey is already hosting about 700,000 Syrian refugees who fled the civil war between the government and the opposition. But the government in Ankara has a history of strained relations with Turkey's Kurdish minority. Zlatica Hoke reports Turkey is asking for international help.
Video

Video Whaling Summit Votes to Uphold Ban on Japan Whale Hunt

The International Whaling Commission, meeting in Slovenia, has voted to uphold a court ruling banning Japan from hunting whales in the Antarctic Ocean. Conservationists hailed the ruling as a victory, but Tokyo says it will submit revised plans for a whale hunt in 2015. Henry Ridgwell reports from London.
Video

Video A Dinosaur Fit for Land and Water

Residents and tourists in Washington D.C. can now examine a life-size replica of an unusual dinosaur that lived almost a hundred million years ago in northern Africa. Scientists say studying the behemoth named Spinosaurus helps them better understand how some prehistoric animals adapted to life on land and in water. The Spinosaurus replica is on display at the National Geographic museum. VOA’s George Putic has more.
Video

Video Iraqi Kurdistan Church Helps Christian Children Cope find shelter in churches in the Kurdish capital, Irbil

In the past six weeks, tens of thousands of Iraqi Christians have been forced to flee their homes by Islamic State militants and find shelter in churches in the Kurdish capital, Irbil. Despite U.S. airstrikes in the region, the prospect of people returning home is still very low and concerns are starting to grow over the impact this is having on the displaced youth. Sebastian Meyer reports from Irbil on how one church is coping.


Carnage and mayhem are part of daily life in northern Nigeria, the result of a terror campaign by the Islamist group Boko Haram. Fears are growing that Nigeria’s government may not know how to counter it, and may be making things worse. More

AppleAndroid