warg6606@uxa.cso.uiuc.edu (12/10/89)
In response to Mr. Hess' questions questions regarding "dinosaur" physiology, I can refer him to any 200 level comparative anatomy textbook. Recalling what I learned in that class when I took it some-odd years ago, some dinosaurs are believed to have been cold-blooded, while others were warm blooded. These data are based on measurements of supposed body-weight and circulatory systems, all of which are extrapolated from skeletons, of course. One must remember that "dinosaurs" is a collective term for a very large group of animals, all of which lived at roughly the same period in bio-geo- logical history. Therefore, one must be careful that they do not stretch comparisons between different species of "dinosaurs" as if they were very closely related, which they may not be (i. e. comparing apples and oranges). In the question regarding the evolutionary relationship of avians to "dinosaurs," reptiles are believed by some evolutionists to be the direct evolutionary ancestors of birds. Since dinosaurs were indeed a class of reptiles, then it can be further stated perhaps that birds are related to what was dinosaurs. General anatomical/morphological evidence of the reptile/avian relationship is the various "reptile-like" characteristics of birds, including "scaly" legs and perhaps even the egg-laying. Since reptiles are still present today, there are existing classes that are very closely related to the one-time dinosaurs. If my memory serves me correctly, these would include turtles. I do not remember the scientific name for this class. I hope this is of use to you. As I said, all of this can be found in a good comparative anatomy textbook. W. R.