Similarities and differences between reptiles and mammals.

Mammals and reptiles, two of the five classes of vertebrates, are some of the most complex animals on Earth. There are approximately 8,240 species of reptiles, including snakes, turtles and lizards, which make them a more diverse group than mammals, of which there are about 5,400 species. It is believed that mammals, including whales, bears, and primates, evolved from reptiles 240 million years ago. Mammals and reptiles have some similarities – for example, they have spinal cords, but they are more different, especially with regard to skin and temperature regulation.