Paleontologists Believe Biggest Dinosaurs Were Hot-Blooded

by amyellensoden | November 11, 2009 at 03:55 pm

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Research by Dr. Herman Pontzer and fellow scientists at the University of Washington, St Louie suggests that larger dinosaurs were hot-blooded creatures due to the expenditure of energy that would be required for them to move. This research centers around dinosaurs' leg bones and muscles, and the amount of energy needed to support body weight.

Their research shows that larger dinosaurs are far more likely to have been endothermic than possessing an unknown alternate physiology. This research is well founded and indicative within larger dinosaurs such as the Tyrannosaurus Rex that possessed high level metabolisms.

Because warm-blooded animals have much greater aerobic capacity than their cold-blooded counterparts, finding bigger muscles and higher energy demands in dinosaurs would favor the warm-blooded hypothesis. Indeed, when Pontzer and colleagues looked at anatomical models of 14 different species of extinct dinosaurs, they were surprised to find that even at a slow walk, most dinos needed more energy than a cold-blooded metabolism could provide.

By studying fossilized leg bones, Dr. Pontzer and his fellow scientists discovered that the energy needed for these larger dinosaurs to even walk and run would require them to be hot-blooded creatures. One particular study involving a CT scan of an ancient dinosaur fossil revealed interesting details of the heart structure that would have been present within the dinosaur:

The new research fits well with a previous study on dinosaur cardiovascular anatomy, based on a CT scan of a 66-million year old dinosaur fossil with a preserved heart. Imaging revealed a four-chambered, double-pump heart with a single aorta — essentially, the heart of a warm-blooded mammal or bird, not a cold-blooded reptile.

It is still debatable whether or not these creatures were hot or cold-blooded, but this new study relating to bone and muscle structure and how that affects the amount of energy expenditure within a dinosaur is an interesting point of consideration.

This new research using a biochemical model reveals further similarities to hot-blooded mammals and certainly indicates a strong possibility that dinosaurs themselves were endothermic.