Life has changed during Earth's long history.

Fungal spores courtesy of Nan Arens, UCMP; Ediacaran animal (Ediacaria) © Lisa Gershwin, UCMP; Trilobite (Elrathia kingi), early vascular plant (Cooksonia), dragonfly (Protolindenia wittei), seed fern foliage (Alethopteris), ammonite, and turtle © UCMP; Early birds (Confuciusornis) © John Hutchinson, UCMP; Triceratops skull, leaves, mammoth skeleton, and hominid skull by Dave Smith © UCMP; King penguin (Aptenodytes patagonicus) by Gerald and Buff Corsi, © 2004 California Academy of Sciences.