Late Ordovician
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The Late Ordovician, also called the Upper Ordovician by geologists, is the third epoch of the Ordovician period.
At this time Western and Central Europe and North America collided to form Laurentia, while glaciers built up in Gondwana, which was positioned over the South Pole. This caused a drop in global temperatures, resulting in "ice house" conditions.
For most of this time life continued to flourish, but at the end of the period there was a mass-extinction that seriously affected planktonic forms like conodonts, graptolites, and some groups of trilobites (Agnostida and Pytchopariida, which compeletly died out, while the Asaphida were much reduced). Brachiopods and bryozoans and echinoderms were also heavily affected, and the endocerid nautiloids died out completely, except for possible rare Silurian forms.
External links
- [Middle & Late Ordovician Climate]
- [The World during the Middle and Late Ordovician] paleogeography
- [The Late Ordovician]
- [GeoWhen Database - Late Ordovician]
- [The Ordovician Mass Extinction]
- [BBC Evolution Weekend: Extinction Files] (very brief entry)
| Ordovician period | |||||
|---|---|---|---|---|---|
| Lower/Early Ordovician | Middle Ordovician | Upper/Late Ordovician | |||
| Tremadocian | Arenigian | Ord. III | Darriwilian | Ord. V | Ord. VI |
| Hirnantian | |||||
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