The beginning of this per
The beginning of this period is marked by the appearance of Treptichnus pedum trace fossils, and the Hawke Bay event signaled an abrupt drop in global sea level in the middle of this period. The Phanerozoic eon began in this pe- riod, whose rocks were first classified by Adam Sedgwick. This period is known for its rich abundance of lagerstatten, with brachiopods as the second most prevalent fossil type, though the best record of this period's fauna is found in British Columbia's Burgess Shale. Having the trilobite as its characteristic fossil, name this period, the first in the Pa- leozoic era, when at least eleven of the present animal phyla evolved in a namesake "explosion".
The beginning of this period is marked by the appearance of Treptichnus pedum trace fossils, and the Hawke Bay event signaled an abrupt drop in global sea level in the middle of this period.
{Cambrian} period