ordovicican

(Ordovician Period – Paleozoic Era) When did the Ordovician Period occur?

488 MYA – 444 MYA

(Ordovician Period – Paleozoic Era) What major marine groups diversified?

New trilobites, brachiopods, echinoderms, gastropods, cephalopods, and corals

(Ordovician Period – Paleozoic Era) What were the first vertebrates?

Jawless fish

(Ordovician Period – Paleozoic Era) What important fossil organisms were widespread?

Graptolites; colonial and widespread

(Ordovician Period – Paleozoic Era) What mountain-building event began during this time?

Acadian Mountain formation

(Ordovician Period – Paleozoic Era) What major extinction event occurred at the end of this period?

Ordovician–Silurian extinction

(Ordovician Period – Paleozoic Era) What caused the Ordovician–Silurian extinction?

Severe ice age that lowered sea level

(Ordovician Period – Paleozoic Era) How severe was the Ordovician–Silurian extinction?

About 60–70% of species and about 57% of genera went extinct