2.75" Diplomystus dentatus & 1.5" Amphiplaga brachyptera | 100% Natural | Green River Formation | Wyoming
Diplomystus approx. size: 2.75"
Amphiplaga approx. size: 1.5"
Matrix approx. size: 5.5" x 4"
Diplomystus is an extinct genus of freshwater clupeomorph fish distantly related to modern-day extant herrings, alewives, and sardines. The genus was first named and described by Edward Drinker Cope in 1877.
Ray-finned Fish - Diplomystus dentatus
Order Ellimmichthyiformes, Family Paraclupeidae
The last known species of the Ellimmichthyiformes order went extinct sometime in the middle Eocene. D. dentatus is a primitive relative of the modern day herring. The genus Diplomystus is also known from fossil deposits in China.
D. dentatus is the 2nd most common fossil fish found from Fossil Lake. Specimens ranging from embryonic size (about 0.7 inches) to full-grown adults (about 26 inches) are common. Smaller-sized specimens are more commonly found in mid-lake than near-shore deposits. This suggests that D. dentatus spawned in open water.
This species' upturned mouth indicates it fed at the surface of Fossil Lake. D. dentatus specimens are commonly found with other fish stuck in their mouths, including other D. dentatus specimens.
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.