¿Qué es el ORDOVÍCICO?
Ordovician Period Overview
The Ordovician period is the second stage of the Paleozoic era, lasting from 485 million years ago to 443 million years ago. It is divided into three main epochs: Lower, Middle, and Upper.
Lower Epoch
- Lasted approximately 15 million years.
- Characterized by a cooling climate and transgression.
- Extension of many brachiopods and decline in trilobite numbers.
Middle Epoch
- Central stage lasting around 12 million years.
- Marked by the appearance of the first conodont species.
Upper Epoch
- Final stage of the Ordovician period, lasting about 15 million years.
- Features include the emergence of some graptolite species, the first major glaciation event, and a significant drop in sea levels.
- This led to a mass extinction event, with an 85% loss of species at that time.
- However, towards the end of this epoch, climate conditions returned to normal and sea levels rose even higher than before.