Fossil Science
Recent News |  Archives |  Tags |  About |  Newsletter |  Submit News |  Links |  Subscribe to FossilScience.com RSS Feed Subscribe


More Articles
Enhanced instrument enables high-speed chemical imaging of tissuesEnhanced instrument enables high-speed chemical imaging of tissues

Lunar pits could shelter astronauts, reveal details of how 'man in the moon' formedLunar pits could shelter astronauts, reveal details of how 'man in the moon' formed

Scientists complete chromosome-based draft of the wheat genomeScientists complete chromosome-based draft of the wheat genome

Study led by indigenous people uncovers grizzly bear 'highway'Study led by indigenous people uncovers grizzly bear 'highway'

Tiny laser sensor heightens bomb detection sensitivityTiny laser sensor heightens bomb detection sensitivity

A crystal wedding in the nanocosmosA crystal wedding in the nanocosmos

Has Antarctic sea ice expansion been overestimated?Has Antarctic sea ice expansion been overestimated?

Boosting the force of empty spaceBoosting the force of empty space

New research: When it hurts to think we were made for each otherNew research: When it hurts to think we were made for each other

Bacteria swim with whole body, not just propellersBacteria swim with whole body, not just propellers

Mixed genes mix up the migrations of hybrid birdsMixed genes mix up the migrations of hybrid birds

Wisconsin scientists find genetic recipe to turn stem cells to bloodWisconsin scientists find genetic recipe to turn stem cells to blood

PIWI proteins and piRNAs regulate genes in the germline and beyondPIWI proteins and piRNAs regulate genes in the germline and beyond

Law of physics governs airplane evolutionLaw of physics governs airplane evolution

Brain waves show learning to read does not end in 4th grade, contrary to popular theory

Running for life: How speed restricts evolutionary change of the vertebral columnRunning for life: How speed restricts evolutionary change of the vertebral column

Getting a grip on robotic graspGetting a grip on robotic grasp

The bend in the Appalachian mountain chain is finally explainedThe bend in the Appalachian mountain chain is finally explained

Cooperation among humans, a question of ageCooperation among humans, a question of age

Protein's 'hands' enable bacteria to establish infection, research findsProtein's 'hands' enable bacteria to establish infection, research finds

Less exercise, not more calories, responsible for expanding waistlinesLess exercise, not more calories, responsible for expanding waistlines

High earners in a stock market game have brain patterns that can predict market bubblesHigh earners in a stock market game have brain patterns that can predict market bubbles

Platonic solids generate their 4-dimensional analoguesPlatonic solids generate their 4-dimensional analogues

A healthy lifestyle adds years to lifeA healthy lifestyle adds years to life

Study of animal urination could lead to better-engineered productsStudy of animal urination could lead to better-engineered products

Do probiotics help kids with stomach bugs?Do probiotics help kids with stomach bugs?

Strict diet suspends development, doubles lifespan of wormsStrict diet suspends development, doubles lifespan of worms

Identified for the first time what kind of explosive has been used after the detonationIdentified for the first time what kind of explosive has been used after the detonation

Copied from nature: Detecting software errors via genetic algorithmsCopied from nature: Detecting software errors via genetic algorithms

Discovery raises new doubts about dinosaur-bird links (6/11/2009)

Tags:
birds, dinosaurs, theropods

Researchers at Oregon State University have made a fundamental new discovery about how birds breathe and have a lung capacity that allows for flight - and the finding means it's unlikely that birds descended from any known theropod dinosaurs.

The conclusions add to other evolving evidence that may finally force many paleontologists to reconsider their long-held belief that modern birds are the direct descendants of ancient, meat-eating dinosaurs, OSU researchers say.

"It's really kind of amazing that after centuries of studying birds and flight we still didn't understand a basic aspect of bird biology," said John Ruben, an OSU professor of zoology. "This discovery probably means that birds evolved on a parallel path alongside dinosaurs, starting that process before most dinosaur species even existed."

These studies were just published in The Journal of Morphology, and were funded by the National Science Foundation.

It's been known for decades that the femur, or thigh bone in birds is largely fixed and makes birds into "knee runners," unlike virtually all other land animals, the OSU experts say. What was just discovered, however, is that it's this fixed position of bird bones and musculature that keeps their air-sac lung from collapsing when the bird inhales.

Warm-blooded birds need about 20 times more oxygen than cold-blooded reptiles, and have evolved a unique lung structure that allows for a high rate of gas exchange and high activity level. Their unusual thigh complex is what helps support the lung and prevent its collapse.

"This is fundamental to bird physiology," said Devon Quick, an OSU instructor of zoology who completed this work as part of her doctoral studies. "It's really strange that no one realized this before. The position of the thigh bone and muscles in birds is critical to their lung function, which in turn is what gives them enough lung capacity for flight."

However, every other animal that has walked on land, the scientists said, has a moveable thigh bone that is involved in their motion - including humans, elephants, dogs, lizards and - in the ancient past - dinosaurs.

The implication, the researchers said, is that birds almost certainly did not descend from theropod dinosaurs, such as tyrannosaurus or allosaurus. The findings add to a growing body of evidence in the past two decades that challenge some of the most widely-held beliefs about animal evolution.

"For one thing, birds are found earlier in the fossil record than the dinosaurs they are supposed to have descended from," Ruben said. "That's a pretty serious problem, and there are other inconsistencies with the bird-from-dinosaur theories.

"But one of the primary reasons many scientists kept pointing to birds as having descended from dinosaurs was similarities in their lungs," Ruben said. "However, theropod dinosaurs had a moving femur and therefore could not have had a lung that worked like that in birds. Their abdominal air sac, if they had one, would have collapsed. That undercuts a critical piece of supporting evidence for the dinosaur-bird link.

"A velociraptor did not just sprout feathers at some point and fly off into the sunset," Ruben said.

The newest findings, the researchers said, are more consistent with birds having evolved separately from dinosaurs and developing their own unique characteristics, including feathers, wings and a unique lung and locomotion system.

There are some similarities between birds and dinosaurs, and it is possible, they said, that birds and dinosaurs may have shared a common ancestor, such as the small, reptilian "thecodonts," which may then have evolved on separate evolutionary paths into birds, crocodiles and dinosaurs. The lung structure and physiology of crocodiles, in fact, is much more similar to dinosaurs than it is to birds.

"We aren't suggesting that dinosaurs and birds may not have had a common ancestor somewhere in the distant past," Quick said. "That's quite possible and is routinely found in evolution. It just seems pretty clear now that birds were evolving all along on their own and did not descend directly from the theropod dinosaurs, which lived many millions of years later."

OSU research on avian biology and physiology was among the first in the nation to begin calling into question the dinosaur-bird link since the 1990s. Other findings have been made since then, at OSU and other institutions, which also raise doubts. But old theories die hard, Ruben said, especially when it comes to some of the most distinctive and romanticized animal species in world history.

"Frankly, there's a lot of museum politics involved in this, a lot of careers committed to a particular point of view even if new scientific evidence raises questions," Ruben said. In some museum displays, he said, the birds-descended-from-dinosaurs evolutionary theory has been portrayed as a largely accepted fact, with an asterisk pointing out in small type that "some scientists disagree."

"Our work at OSU used to be pretty much the only asterisk they were talking about," Ruben said. "But now there are more asterisks all the time. That's part of the process of science."

Note: This story has been adapted from a news release issued by the Oregon State University

Post Comments:

Search
New Articles
Dinosaurs fell victim to perfect storm of events, study shows

The economic territory of Upper Palaeolithic groups is specified by flintThe economic territory of Upper Palaeolithic groups is specified by flint

Mammoth and mastodon behavior was less roam, more stay at homeMammoth and mastodon behavior was less roam, more stay at home

3-D image of Paleolithic child's skull reveals trauma, brain damage3-D image of Paleolithic child's skull reveals trauma, brain damage

Leaf-mining insects destroyed with the dinosaurs, others quickly appearedLeaf-mining insects destroyed with the dinosaurs, others quickly appeared

Meet the gomphothere: UA archaeologist involved in discovery of bones of elephant ancestorMeet the gomphothere: UA archaeologist involved in discovery of bones of elephant ancestor

Prehistoric 'bookkeeping' continued long after invention of writingPrehistoric 'bookkeeping' continued long after invention of writing

New feathered predatory fossil sheds light on dinosaur flightNew feathered predatory fossil sheds light on dinosaur flight

Tooth plaque provides insight into our prehistoric ancestors' dietTooth plaque provides insight into our prehistoric ancestors' diet

Brain of world's first known predators discoveredBrain of world's first known predators discovered

Extinct sea scorpion gets a eye exam, with surprising resultsExtinct sea scorpion gets a eye exam, with surprising results

One secret of ancient amber revealed

Researchers declassify dinosaurs as being the great-great-grandparents of birdsResearchers declassify dinosaurs as being the great-great-grandparents of birds

Ancient arachnid brought back to 'life'

Ancient hedgehog and tapir once inhabited British ColumbiaAncient hedgehog and tapir once inhabited British Columbia



Archives
July 2014
June 2014
May 2014
April 2014
March 2014
February 2014
January 2014
December 2013
November 2013
October 2013
September 2013
August 2013
July 2013
June 2013
May 2013
April 2013
March 2013
February 2013
January 2013
December 2012
November 2012
October 2012
September 2012
August 2012
July 2012
June 2012
May 2012
April 2012
March 2012
February 2012
January 2012
December 2011
November 2011
October 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
March 2011
February 2011
January 2011
December 2010
November 2010
October 2010
September 2010
August 2010
July 2010
June 2010
May 2010
April 2010
March 2010
February 2010
January 2010
December 2009
November 2009
October 2009
September 2009
August 2009
July 2009
June 2009
May 2009
April 2009
March 2009
February 2009
January 2009
December 2008
November 2008
October 2008
September 2008
August 2008
July 2008
June 2008
May 2008
April 2008
March 2008
February 2008
January 2008
December 2007
November 2007
October 2007
September 2007


Science Friends
Agricultural Science
Astronomy News
Biology News
Biomimicry Science
Cognitive Research
Chemistry News
Tissue Engineering
Cancer Research
Cybernetics Research
Electonics Research
Forensics Report
Genetic Archaeology
Genetics News
Geology News
Microbiology Research
Nanotech News
Parenting News
Physics News


  Archives |  Submit News |  Advertise With Us |  Contact Us |  Links
Use of this site constitutes acceptance of our Terms of Service and Privacy Policy. All contents © 2000 - 2015 Web Doodle, LLC. All rights reserved.