300861 Lecture Notes - Lecture 27: Amniote, Cloaca, Vestigiality
17 May 2019
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Document Summary
The rate of respiration, like so many physiological activities of reptiles, is highly variable, depending in part upon the temperature of the environment and in part upon the emotional state of the animal. The digestive system of modern reptiles is similar in general plan to that of all higher vertebrates. It includes the mouth and its salivary glands the esophagus, the stomach, and the intestine and ends in a cloaca. Of the few specializations of the reptilian digestive system, the evolution of one pair of salivary glands into poison glands in the venomous snakes is the most remarkable. During development the embryos of higher vertebrates (reptiles, birds, and mammals) consecutively develop three separate sets of kidneys; these are arranged in longitudinal sequence in the body cavity. The first set, the pronephroi, are vestigial organs left over from the evolutionary past that soon degenerate and disappear without having had any function.
