The organisms in Class Reptilia are the first fully terrestrial vertebrates. They appeared first in thee paleozoic era and grew so numerous that the mexozoic is known as the age of reptiles. The eggs of these reptiles are cleidoic or closed and self contained. The shell is relatively impermeable. The lungs of the reptilia are used for resperation and the heart has two atria and one ventricle and it is partially or totally divided. Their skin is covered with scales or bony plates and they are ectothermic or heliothermic because they either need to move to a new location to regulate body temp or can use solar radiation.
American Alligatot (Alligator Mississippiensis)
Diversity of vertebrates. (2010). Retrieved from http://www.shsu.edu/~bio_mlt/Chapter3.html
