Earth history; Ordovician
In the Ordovician, the continents lay along the Equator and to the south of it. The calcareous sediments that we find, tell us that at this time, there were large, shallow seas with clear and warm water. This provided a good environment for algal growth which in turn was food for a teeming animal life:
- corals, sponges, bryozoans and lime producing algae (reef builders)
- trilobites, brachiopods, gastropods and echinoderms (reef dwellers)
- shell bearing cephalopods (nautiloids), which developed gas-filled chambers, were active swimmers and were probably among the first real predators.
Publisert 30. jan. 2009 09:04 - Sist endret 18. mai. 2011 16:00