An Ordovician drama - a large nautiloid captures a trilobite. The Ordovician Period is the second period of the Paleozoic Era. This important period saw the origin and rapid evolution of many new types of invertebrate animals which replaced their Cambrian predecessors.
Primitive plants move onto land, until then totally barren.
The supercontinent of Gondwana drifted over the south pole, initiating a great Ice Age that gripped the earth at this time. The end of the period is marked by an extinction event. The Ordovician System of strata was founded by Lapworth in 1879 to resolve the Murchison-Sedgwick conflict over their overlapping claims for their Silurain and Cambrian systems. The Ordovician was originally divided into two sub-periods, Bala and Dyfed. But more recently the Tremadoc epoch was removed from the Cambrian and a three-fold division of Ordovician strata instituted.