Invertebrate fossils in Kansas

Invertebrates are animals without backbones, including insects, sponges, corals, and clams. Whatever invertebrates lack in drama compared to their vertebrate counterparts, they make up for in sheer numbers.

Invertebrate fossils are easy to find in Kansas rocks and far more common than vertebrate or plant fossils. Most are marine animals that lived in seas that covered Kansas at various times in the distant past. The relatively few terrestrial (land) fossils found in Kansas include insects that lived in swampy areas. Some of the most common invertebrates are

• ammonoids (squidlike creatures that lived inside a shell)
• brachiopods (marine animals that secrete a shell consisting of two parts called valves)
• bryozoans (small animals that live exclusively in colonies)
• clams and their relatives
• corals (simple animals that secrete skeletons made of calcium carbonate)
• crinoids (relatives of starfishes and sea urchins that resemble flowers)
• fusulinids (single-celled organisms about the size and shape of a grain of wheat)
• insects
• gastropods (snails and their relatives)
• sponges (one of the simplest multicellular animals living today)
• trilobites (arthropods whose closest living relative is the horseshoe crab)