21170 - Premium Grade Soft Bodied Xiphosurid (Horseshoe Crab Ancestor) Lower Ordovician Dinosaur Chondrichthyes - Lamniformes - Odontaspididae

Chondrichthyes - Lamniformes - Odontaspididae

Beautiful example of a polished 9

niobium and copper

Ascocystites sp: Fossilworks (Paleobiology Database)

Trilobita - Asaphida - Cyclopygidae

21170 - Premium Grade Soft Bodied Xiphosurid (Horseshoe Crab Ancestor) Lower Ordovician Dinosaur Chondrichthyes - Lamniformes - OdontaspididaeXiphosurans are an order of arthropods related to arachnids, or, according to one recent study, actually arachnids. They are sometimes called horseshoe crabs (a name applied more specifically to the only extant family, Limulidae). They first appeared in the Tremadocian (Lower Ordovician) from Fezouata Fm in South Morocco. Currently, there are only four living species. They are members of the order Xiphosura, which contains two suborders, Xiphosurida