Wisconsin Act 162 amended Section 1.10 to desig-nate the trilobite as the official state fossil. The trilobite is an extinct marine arthropod with multiple sets of paired, jointed legs. Its head and tapering body were armored in an exoskeleton that was repeatedly molted as the animal grew. Trilobites flourished in the warm, shallow salt water sea that periodically covered Wisconsin territory hundreds of millions of years ago. Their fossil remains average 1 to 2 inches in length.
Trilobite fossils are abundant and distinctive enough to be easily recognized.
Good specimens are preserved in rock formations throughout most of Wisconsin. The Wisconsin Geological Society proposed the fossil to symbolize Wisconsin's ancient past and encourage interest in the state's rich geological heritage. A major rival for recognition as state fossil was the mastodon, a large prehistoric, elephant-like creature. 1985 Wisconsin Act 295 amended Section 1.10 to name the American water spaniel as Wisconsin's official state dog. Enactment of the law was the culmina-tion of years of effort by eighth grade students of Lyle Brumm at Washington Junior High School in New London.