ordovician siluran

9 Cambrian and Ordovician Animals by MickeyRayRex on DeviantArt Ordovician animals were primarily marine invertebrates with a significant increase in species diversity, including armored jawless fish, large squid-like cephalopods with conical shells, and bottom-dwelling creatures like trilobites, brachiopods, crinoids, and sponges. These marine animals lived in a world of shallow seas, while the earliest land plants and some terrestrial arthropods began to appear, though the land was not yet teeming with complex animal life.