Replies

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.

Brooding pythons can raise their body temperature above ambient by shivering - making muscular contractions. Leatherback turtles also have body temperatures above ambient.

They are reptiles.

I think the problem in dealing with extinct forms is they don’t fit the same mold as contemporary reptiles do.

Warm-blooded creatures, like mammals and birds, try to keep the inside of their bodies at a constant temperature. They do this by generating their own heat when they are in a cooler environment, and by cooling themselves when they are in a hotter environment. To generate heat, warm-blooded animals convert the food that they eat into energy. They have to eat a lot of food, compared with cold-blooded animals, to maintain a constant body temperature. Only a small amount of the food that a warm-blooded animal eats is converted into body mass. The rest is used to fuel a constant body temperature.

http://coolcosmos.ipac.caltech.edu/image_galleries/ir_zoo/coldwarm.html

more infrared pictures via the link above.