Eaters and eaten as the test of warm-bloodedness
I tested this idea by calculating the speeds indicated by foot-prints made by living species. (dinosaur equipment)As expected, average walking speed today is much higher in mammals than in cold-blooded amphibians and reptiles. I then calculated walking speeds from the foot-prints of fossil mammals. They fell into the range of their modern, living relatives, confirming that extinct mammals had as high a me tabolism as modern. Next, I turned to testing this idea against the footprints of the very primitive reptiles and the amphibians of the Coal Age—species more archaic in bone structure than living lizards. Once again, the hypothesis proved out. Average speed in the ancient Coal Age and Early Permian animals was exceptionally low, only one to two miles per hour. This was dramatic proof that a leisurely mode of foraging was in fact a concomitant of cold-bloodedness.
Having established the reliability of this approach, (Dinosaur Playground Equipment)I finally turned to calculating the average walking speeds for the dinosaurs and for their ancestors of the Triassic, the thecodonts. There was absolutely no ambiguity in the figures: Dinosaurs and the thecodonts before them moved through their Mesozoic world at average speeds as high as those of warm-blooded mammals and much higher than those of the cold-bloods. Such speeds make evolutionary sense only if metabolic rates were constantly demanding ingestion of calories at a thoroughly warm-blooded rate.
There are, then, three ways of accomplishing the apparently impossible, of counting calories in species long extinct. And the conclusion to be drawn from all three methods coincides precisely. (dinosaur costume)The fossil animals that have low predator-to-prey ratios are the ones that also have bone texture indicating fast growth, and also had high average walking speeds. The picture of dinosaurs painted by these three sources of information is one where the metabolic levels were set on high, where the drama of growing to adulthood was acted out speedily, and where the cast of characters was in constant motion about the Mesozoic landscape, engulfing prodigious quantities of indispensable food.