Introduction to the Tetrapoda

The Four-Legged Vertebrates

The word "Tetrapoda" means "four legs" in Greek. Amphibians, reptiles (including dinosaurs and birds) and mammals are the major groups of the Tetrapoda.

Tetrapods include all land-living vertebrates, such as frogs, turtles, hawks, and lions. The group also includes a number of animals that have returned to life in the water, such as sea turtles, sea snakes, whales and dolphins, seals and sea lions, and extinct groups such as plesiosaurs, ichthyosaurs, and mosasaurs.

Some tetrapods, like whales and snakes, have lost some or all of the four limbs that their ancestors had, but because of their ancestry they are still grouped as tetrapods.

Tetrapods are part of a larger groups called Sarcopterygii, which also includes several groups of lobe-finned fish, such as lungfish and the coelacanth. The Sarcopterygii are just one group of vertebrates, or animals with a backbone.

Click on the buttons below to find out more about the Tetrapods.

For more information, try:

The Terrestrial Vertebrates Pages (by Dr. Michel Laurin while he was a postdoctoral student at Berkeley) on the Tree of Life Website at the University of Arizona.

Pico Blanco Robber Frog photo courtesy Andrew J. Crawford.
Lion and Antarctic Fur Seal photos courtesy Gerald and Buff Corsi California Academy of Sciences.
Red Tailed Hawk photo courtesy 2004 George W. Hartwell.
Green Tree Python photo courtesy John White.