The giant sea scorpion was an enormous predatory aquatic ... This prehistoric creature was a stem-group arthropod from the early Ordovician Era, 480 million years ago. It was the largest animal ...

Ordovician reefs were also home to large sea lilies, relatives of sea stars. Anchored to the bottom inside calcareous tubes, they collected food particles with feathery arms that waved in the ...

But first there was a period of biological regrouping following the disastrous climax to the Ordovician. The recovery soon got under way in the oceans as climbing temperatures and rising sea ...