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[Jabberwocky]

http://news.bbc.co.uk/1/hi/sci/tech/8453053.stm

Alligators and birds share a breathing mechanism which may have helped their ancestors dominate Earth more than 200 million years ago, scientists say.
Research published in the journal Science found that like birds, in alligators air flows in one direction.
Birds' lung structure allows them to breathe when flying in low oxygen, or hypoxic, conditions.
This breathing may have helped a common ancestor of birds and alligators thrive in the hypoxic period of the Triassic.
Mammals 'hiding'
"It might explain a mystery that has been around for quite some time", Dr Colleen Farmer from the University of Utah told BBC News.
The mystery in question is why the archosaurs came to dominate Earth after the planet's worst mass extinction 251 million years ago.

It implies that all dinosaurs... had bird-like lungs
Dr Colleen Farmer
Archosaurs evolved into two different branches which developed into crocodilians, dinosaurs, flying pterosaurs and eventually birds.
Synapsids, which evolved to include mammals, had been dominant in the Permian period before the mass extinction.
Some survived but were toppled from their perch by the archosaurs.
Any mammal-like synapsid survivors "were teeny liittle things hiding in cracks" said Dr Farmer. "I think it's because they couldn't compete.
"It wasn't until the die-off of the large dinosaurs 65 million years ago that mammals made a comeback and started occupying body sizes larger than an opossum."
To demonstrate alligator lung mechanisms, the scientists measured airflow in anesthetised animals, showing it flows in one direction rather than in and out of chambers.
They also pumped water containing tiny fluorescent beads into the lungs of dead alligators to observe the flow.

Studies on these alligators may explain why some animals ruled the Earth.
Puzzle solved
The researchers believe the similarity in lung structure may explain why some animals were better able to adapt after the extinction, when oxygen levels dropped.
"We know that birds are really good at breathing in hypoxic conditions. They can fly at altitudes that would kill a mammal," said Dr Farmer.
"Many archosaurs, such as pterosaurs, apparently were capable of sustaining vigorous exercise. Lung design may have played a key role in this capacity.
"That's been a puzzle, why do birds have these very different lungs? But now we can date it back to the common ancestor of birds and crocodilians.
"It implies that all dinosaurs, herbivores like Triceratops and carnivores like Tyrannosaurus, had bird-like lungs," Dr Farmer added.

[suitcase]

That's really cool. Thanks for sharing. I love learning something new.

[Jabberwocky]

it seems a more efficient way to breath. I am sure DD will be along to explain why it would not work for humans

[darwin dali]

By examining the heart of a crocodile, Queensland researchers have discovered how it is that an air-breathing creature can manage to cruise through the murk, for several hours without surfacing.

This week in Nature [August, 2000, DD] the researchers report the crocodile has a unique type of valve in its heart which actively controls blood flow between the lungs and the rest of the body.

University of Queensland researcher, Craig Franklin, together with University of Goteborg colleague Michael Axelsson have been studying the heart of the estuarine crocodile, Crocodylus porosus.

"These valves represent an absolute evolutionary novelty," said Dr Franklin. "They are further proof of the complexity and sophistication of the 'plumbing' and general anatomy of the crocodile family," Dr Franklin said.

Unlike the passive flap-like valves of other vertebrates, the crocodile valve has cog teeth made up of nodules of connective tissue. The cog teeth mesh together, diverting blood away from lungs and into their bodies. The researchers have found that these "teeth" are controlled by the amount of adrenalin in the bloodstream.

"When the crocodile is relaxed, the absence of adrenalin acts to close the cog-teeth valves," Dr Franklin said. He said this mechanism may allow the crocodiles to dive for several hours without needing to resurface to breathe.

The valves are situated in the crocodile's right ventricle, which pumps blood to the pulmonary artery feeding the lungs as well as to the left aorta which supplies the body. The cog-teeth valve can divert blood going to the lungs back into the body, a phenomenon known as a shunt.

"In contrast, mammalian hearts are very inflexible with the blood supply to the lungs a separate activity to that feeding the body."

"Crocodiles are an endless source of fascination for people because they are one of the few animals which can still get the better of us. We now know that far from being primitive or basic, their heart is a remarkable machine," Dr Franklin said.

[bud]

I find the fact birds are direct descendants from theropod Dinosaurs infact can be still classed as Dinosaurs more interesting

[suitcase]

By examining the heart of a crocodile, Queensland researchers have discovered how it is that an air-breathing creature can manage to cruise through the murk, for several hours without surfacing.

This week in Nature [August, 2000, DD] the researchers report the crocodile has a unique type of valve in its heart which actively controls blood flow between the lungs and the rest of the body.

University of Queensland researcher, Craig Franklin, together with University of Goteborg colleague Michael Axelsson have been studying the heart of the estuarine crocodile, Crocodylus porosus.

"These valves represent an absolute evolutionary novelty," said Dr Franklin. "They are further proof of the complexity and sophistication of the 'plumbing' and general anatomy of the crocodile family," Dr Franklin said.

Unlike the passive flap-like valves of other vertebrates, the crocodile valve has cog teeth made up of nodules of connective tissue. The cog teeth mesh together, diverting blood away from lungs and into their bodies. The researchers have found that these "teeth" are controlled by the amount of adrenalin in the bloodstream.

"When the crocodile is relaxed, the absence of adrenalin acts to close the cog-teeth valves," Dr Franklin said. He said this mechanism may allow the crocodiles to dive for several hours without needing to resurface to breathe.

The valves are situated in the crocodile's right ventricle, which pumps blood to the pulmonary artery feeding the lungs as well as to the left aorta which supplies the body. The cog-teeth valve can divert blood going to the lungs back into the body, a phenomenon known as a shunt.

"In contrast, mammalian hearts are very inflexible with the blood supply to the lungs a separate activity to that feeding the body."

"Crocodiles are an endless source of fascination for people because they are one of the few animals which can still get the better of us. We now know that far from being primitive or basic, their heart is a remarkable machine," Dr Franklin said.

Awesome information!