Paleozoic Ocean Life

Shown below is a small sample of the rich diversity of marine life during the Paleozoic Era.

This reconstruction of a shallow, tropical sea (U.S. National Museum) shows the high diversity of corals that characterized the Paleozoic. While superficially similar to modern forms, most the types shown here are extinct.

Superficially similar to modern clams, members of the Phylum Brachiopoda dominated the sea-bottom communities. Shown here is a Devonian-aged Mucrospirifer. The evolution of more advanced predators near the end of the Paleozoic caused a rapid decline in brachiopod diversity and there are few examples alive today.

Cephalopod mollusks were highly diverse during the Paleozoic. Some, like this living Nautilus had coiled shells, while still others had long, straight shells.

Trilobites were the most diverse arthropods in the early Paleozoic seas, particularly in the Cambrian. This is a Dalmanites from Silurian-age rocks in Indiana.

Here is a Eurypterus (Silurian) that is about 30 cm long. The Eurypterids were swimming arthropods that were probably the most fearsome predators of the Paleozoic until the rise of various jawed fishes. Some reached a maximum length of two meters!

Crinoids are stalked echinoderms, almost extinct today, related to sea stars. This U.S. National museum reconstruction shows numerous crinoids as they would have appeared in the early Carboniferous.

Ralph E. Taggart (taggart@msu.edu)