Mesolimulus

Mesolimulus is an extinct genus of arthropod. The best known examples are found in Solnhofen limestone near Solnhofen, Bavaria, Germany. Originally assigned to the living genus Limulus, they are related to and look virtually identical to the modern horseshoe crab.

Jurassic Park
Mesolimuulus has never appeared or metioned in any jurassic park films or books, it has however appeared in Jurassic Park III: Park Builder.