Green River Fossil Prawn (Decapod)

Name: Bechleja rostrata

Phylum Arthropoda; Subphylum Crustacea; Order Decapoda; Suborder Pleocyemata; Infraorder Caridea; Family Palaemonidae

Geological Time: Eocene

Size: 65 mm in length (tip of rostrum to tip of telson); on a 208 mm by 185 mm matrix

Fossil Site: Green River Formation, Fossil Lake, Kemmerer, Wyoming

Bechleja rostrata fossilThis 50 million year old, Eocene-Era fossil prawn comes from one of the world's famous Laggerstatten, the Green River Formation in Wyoming. A small portion of the fossils from Green River exhibits such fine preservation. Most fossils offered are various fish, but other fossils are also found, albeit much more rarely. Indeed, members of this species are found only on the order of frequency of the highly-prized stingray Heliobatis.

This prawn has wonderful details present, and represents the finest degree of preservation. Notice that even the annulation of the antennae is evident. Decaopds have a spotty fossil record beyond 30 million years, but Bechleja from the Green River Formation is an exception. There are 3 other members of the genus, all from the Oligocene, found in Germany and Brazil. Pleocyematans are united by a number of characteristics, most notably that the fertilized eggs are incubated by the female, and remain stuck to the pleopods (swimming legs) until they are ready to hatch.

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