1.5" Amphiplaga brachyptera | Green River Formation | Wyoming
Amphiplaga brachyptera Eocene (51.98 Million Years Ago) Private Quarry, Green River Formation, Wyoming, USA Preparation by Jim Tynsky Amphiplaga approx. size: 1.5" Matrix approx. size: 2.5" x 2" Apmhiplaga is a member of the Family Percopsidae under the Order Percopsiformes. The family is referred to as trout-perch due to a superficial resemblance to trout and perch, but percopsids are not closely related to either group. Percopsiformes are generally small fish, ranging in size from 2 to 8 inches. Amphiplaga brachyptera is a relatively rare species of the Green River Formation, making up less than one percent of the fish population. They occur mostly in nearshore beds of Fossil Lake, but some have been found in mid-lake beds. Larval stage Amphiplaga are almost unheard of in mid-lake beds, suggesting that they spawned upriver in the northern tributary of Fossil Lake. Modern percopsids also spawn in streams or gravel in lake shallows. This species is never found in mass mortality, suggesting that is was a solitary rather than a schooling fish.