Procambarus primaevus
Crustacean
Early Eocene
Green River Formation
Kemmerer, Wyoming, USA

48mm to tip of antenna freshwater crayfish on 69mm slab.

Arthropod. Crustacean.

Procambarus is a genus of freshwater crayfish and this may be its earliest occurrence.  This species, P. primaevus, is actually one of the first invertebrates ever described from the Green River sandwich (“split fish”) beds.  The genus still lives today in North and Central America, preferring warm, slow-moving river, stream, or marsh habitats.

Interesting study specimen of this rare crustacean.