FOSSIL HORSESHOE CRABS (SOLNHOFEN)

Horseshoe crabs are Arthropods of the Family Limulidae, Order Xiphosura. Related to eurypterids, they first evolved during the Ordovician Period, about 450 million years ago. They are brackish water dwellers with large shells, tiny eyes, and tails. Sometimes labeled as "living fossils", four species are still alive today. Horseshoe crabs are rare in the fossil record, but some examples can be very striking.