Answer:
Mammals and reptiles, two of the five classes of vertebrates, are among the most complex animals on Earth. There are approximately 8,240 species of reptiles, including snakes, turtles and lizards, which make it a more diverse group than mammals, of which there are about 5,400 species. Mammals, which include whales, bears and primates, are believed to have evolved from reptiles 240 million years ago.