Arthropoda (Bug-like animals)
Crabs, lobsters, shrimp ( Crustacea)
Although crustacean fossils are found in Kentucky, the most common types are generally microscopic forms called ostracodes. Ostracodes (Ostracoda) are tiny crustaceans (sand size) that have two shells that look like clam shells. Micropaleontologists study ostracodes because they are useful in determining the relative age of the rock they are found in. One giant ostracode, Leperditia, about the size of a finger nail, can sometimes be found in the Ordovician rocks in the central part of the Blue Grass Region. Shrimp-like crustaceans have also been found in the Pennsylvanian rocks of the Eastern Kentucky Coal Field.
Scorpions, spiders (Arachnid)
Giant water scorpions, as much as 5 feet long, may have lived in Kentucky during the Paleozoic Era, but fossils have not been found. Spider fossils have the potential to be found in the Pennsylvanian rocks of Kentucky's two coal fields.
Horseshoe crabs, etc. (Merostomata)
Tracks from horseshoe crabs have been found in the Pennsylvanian rocks of the Eastern Kentucky Coal Field. These ancient horseshoe crabs were only a couple of inches long. Modern horseshoe crabs, up to 2 feet long, live in the sea and can be seen in Florida.
A millipede fossil was found recently in the Pennsylvanian rocks of the Western Kentucky Coal Field. This millipede had large spines all along its body. Fossil trackways of giant millipedes called Arthropleura (animals up to 5 feet long) have been found in other areas of eastern North America and could probably be found in Kentucky.
The first insect fossil found in Kentucky (1980) was an insect wing from the Pennsylvanian rocks of the Eastern Kentucky Coal Field. It came from an animal that had a wing span of about 4 inches, looked somewhat like a dragonfly, and could not fold up its wings. Other insect fossils will probably be found in Kentucky.