What is the Cambrian Period?
The Cambrian period is a geologic period that extends from 542 to 488 million years ago. For many decades, it was famous for being thought of as the first geologic period to contain multicellular life. Since 1967, however, scientists have determined that multicellular life did exist prior to the Cambrian period (in the Ediacaran period), though most of it was quite simple and non-motile, consisting of fronds and bags with a distinct quilted appearance. Still, the Cambrian era was the first to contain truly complex life — including the precursors of most modern animal phyla. By contrast, only a few representatives of modern phyla are found in the Ediacaran.
