One of the most important results of certain animals' metabolic processes, including our own, is homeothermy. Click here and scroll down the page to see definitions of homeothermic, poikilothermic, endothermic, and ectothermic. We will return to the topic on this page, and some of the links provided, a little later.

It is interesting and important to biologists to know something about the metabolism of a given plant or animal. Among humans, for example, such information helps us to treat disease, improve proper nutrition, and in general enrich our quality of life. From metabolic studies of animals, we have learned a great deal of value to human metabolic research. A homeothermic animal, for instance, has quite an advantage in meeting the challenges of the environment over that of a poikilothermic animal.

Humans are quite accustomed to thinking of the mammals and birds having body temperatures largely independent of environmental temperatures. Usually the body temperatures of these animals is higher than the ambient, or surrounding, air temperature. If the air temperature is too cool, your body's metabolic system provided more heat. If too hot, behavior (staying in the shade, being active at night) and mechanisms such as perspiring help keep the body temperature normal. By no means can all "warm-blooded" animals perspire, but, like your pet dog, they can pant and stay out of the sun.

Fish are probably universally thought of as "cold-blooded" by the layman. After all, have you ever heard of a warm-blooded fish? No? Click here , and scroll down the page to B4. Surprised?

Modern reptiles are also thought of as cold-blooded, but, click here , and read the entire web page. It is interesting and not long.

To understand our own metabolism it is quite useful to know something of the metabolism of as many organisms as possible. But how does one study the metabolism of something that is extinct, as, for example, the dinosaurs? Before we look into that, click here to help clarify just what we mean when we use the term warm-blooded.

Now that you have a good idea about what is meant by saying that something is warm-blooded, let's take a look at a Summary of the Metabolism Debate involving dinosaurs.

At the end of the Summary are two important web pages you must view because they will give you an idea of what to look for when trying to decide something like whether or not dinosaurs were warm-blooded. Just so you don't miss them, here they are: The Evidence for Endothermic Dinosaurs , and The Evidence for Ectothermic Dinosaurs.

For Investigation
For each inquiry, write your thoughts in a short paragraph for later comparison.

1. A. According to our definitions, could an animal be both endothermic and poikilothermic? B. Ectothermic and homeothermic?
2. Form your own concept of warm-bloodedness and cold-bloodedness, and write it down in a short paragraph. You will have already noticed that science uses these terms somewhat loosely. Therefore, don't hesitate to interpret the facts, comments, and thoughts provided in these Web pages in your own way.
3. In the last Web page mentioned above, The Evidence for Ectothermic Dinosaurs, an interesting hypothesis is mentioned involving respiratory turbinates. Do a little searching on your own of the Web to see if you can find anything further about these structures. There are a number of good search engines available on the Web. I tried only two: Open Text Index , and AltaVista . Both came up with a couple of articles mentioning respiratory turbinates and dinosaurs. If you are not quite familiar with the search engine you are using, be sure to click on their Help button. They all have ways of improving your search. You will find that articles talking about something as esoteric as respiratory turbinates are usually very temporary. If you have no luck, there is a short discussion of these structures on the Answers page.
         The questions here are: do dinosaurs have respiratory turbinates? Are such structures necessary for endothermy? Do they merely indicate endothermy? Are they inconclusive evidence for endothermy?
4. Do you think dinosaurs were ectothermic or endothermic? Briefly state your reasons.