The Taconic orogeny continued the mountain-building begun during the previous period, and the Rheic Ocean formed along with the supercontinent (*) Gondwana.
This period's major index fossil is the trilobite Bathyurus extans, though trilobites declined in importance in the late stages. The Taconic orogeny continued the mountain-building begun during the previous period, and the Rheic Ocean formed along with the supercontinent (*) Gondwana. The Himantian stages of this period saw mass extinctions affecting trilobites, echinoderms, and conodonts, probably resulting from an ice age and drop in sea levels. Graptolites and clams first appeared during this time, though most importantly, plants and animals first began to move onto land. For 10 points, identify this geologic period between the Cambrian and Silurian periods.
This period's major index fossil is the trilobite Bathyurus extans, though trilobites declined in importance in the late stages.
{Ordovician} period