Posted on 06/11/2010 2:17:29 PM PDT by JoeProBono
Giant reptiles that ruled dinosaur-era seas might have been warm-blooded, a new study says.
Researchers found that ancient ocean predators possibly regulated their body temperatures, which allowed for aggressive hunting, deep diving, and fast swimming over long distances.
(See "Giant 'Sea Monster' Fossil Discovered in Arctic.")
"These marine reptiles were able to maintain a high body temperature independently of the water temperature where they lived, from tropical to cold-temperate oceanic domains," said study co-author Christophe Lécuyer, a paleontologist at Université Claude Bernand Lyon 1 in France.
The prehistoric reptiles may have had body temperatures as high as 95 to 102 degrees Fahrenheit (35 to 39 degrees Celsius)—comparable to those of modern dolphins and whales, Lécuyer noted. (See whale pictures.)
Most modern reptiles and fish are cold-blooded, which means their internal temperatures vary along with those of the surrounding water.
Since the modern oceans' top predators—such as tuna and swordfish—are to some degree warm-blooded, this made the team wonder if ancient marine reptiles might have been, too, Lécuyer said.
Tuna and swordfish are homeothermic, or capable of keeping their body temperatures relatively constant, despite changing environmental temperatures. The predators are also partially endothermic, which means they can generate and retain enough heat to raise their body temperatures to high but stable levels.
Most animals thought of as warm-blooded, including mammals and birds, are also both homeothermic and endothermic
The topic is warm-blooded reptiles, not gay ones.
What’s with the picture of Helen Thomas?
Sorry. It was a cheap camera, and the depth of field wasn’t set properly. Plus my hand was shaking while I took the picture. I mean, how lucky can one get to actually have a camera on hand when something like that happens right in front of you?
I’m sure the Russians want to include it in their report on the Polish President’s plane crash!
I read that the real ruler of the sea at that time were the giant ancestors of the Great White Sharks.
does this suit make my thighs look fat? Now tell me the truth!
ok...you win
;-()
Uh, why do you ask that?
Warm-blooded and cold-blooded is such an imprecise way of putting it. In birds and mammals, the atria and ventricles in the heart are divided into two halves, so all blood goes on a path from heart to body to heart to lung to body. No mixing of oxygen-enriched blood with oxygen-depleted blood, so the blood is twice as effective at delivering oxygen, requiring half as much loss of body heat spent distributing oxygen. The body is so efficient that even at rest, an elevated temperature can be maintained.
There are other ways of increasing efficiency, however. Tuna just have a two-section heart, rather than the four-section heart of birds and mammals. Blood simply travels from the heart to the body or gills, back to the heart. However, their gills use the same cross-current exchange to super-oxygenate blood that our kidneys use to super-purify blood. That efficiency helps tuna maintain body temperature, even in cold-water dives, allowing them to swim faster than their prey whose metabolic rates are slowed by the cool water.
|
|
|||
Gods |
Thanks JoeProBono! To all -- there are various shades of gray, the animal kingdom is no longer divided between ectotherms and endotherms. :') |
||
|
· Discover · Nat Geographic · Texas AM Anthro News · Yahoo Anthro & Archaeo · Google · · The Archaeology Channel · Excerpt, or Link only? · cgk's list of ping lists · |
|||
Yeeeesssssssss?
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.