P. colorado The holotype of
P. colorado, the type species of the genus, is from the Middle Eocene-aged Green River Shale, Parachute Creek Member, near Raydome,
Colorado. Durden and Rose, in their 1978 paper, compare
P. colorado to the extant
Baronia brevicornis, and suggest that
P. gracilis may be the same species as
P. colorado, and that the differences between the two are possibly due to
sexual dimorphism.
P. gracilis As with
P. colorado, the holotype of
P. gracilis was from the same site in Colorado. It differs from the type species in being smaller and more gracile in form, though anatomical differences may be due to sexual dimorphism. ==References==