Ordovician

If the Cambrian was characterized by Trilobites inventing skeletons, the Ordovician was when trilobite’s copyright expired…

The Ordovician began 485 million years ago, and it ended 443 million years ago. It was the period when the seas were ruled by large squid ancestors which had straight shells. The first coral reefs were built up and different arthropods and echinoderms lived in the reef areas. Clams and brachiopods were also inhabitants there. In the water, graptolites thrived around. On the coast, first lifeforms, maybe lichens, started to conquer the land. The vertebrates were armoured jawless fishes. The climate started to cool down and at the end, there was an ice age with the first big mass extinction. On the picture, you can see the huge squid ancestors Endoceras with its straight, chambered shell, and Lituites, whose shell is coiled at the beginning. There are also corals, different echinoderms, brachiopods, graptolites and huge trilobites. In the water, jawless fishes like Astraspis are swimming around.