10.6" Uncommon Fish Fossil (Mioplosus) - Wyoming

This is a very nice 10.6" long fossil fish (Mioplosus labracoides), one of the more uncommon species from the Green River Formation. It was collected from the 18 inch layer at a quarry near Kemmerer, Wyoming. Excellent preservation and preparation, with two bonus coprolite (poop fossils) on the caudal fin.

This specimen comes with a metal/acrylic display stand.

Mioplosus is a genus of large, extinct, perciform fish that lived through the Eocene epoch. This genus is easily distuigished by their elongate fusiform body, double dorsal fins, and forked tail. Mioplosus was a solitary predator with large teeth and a few fossil specimens have been collected with other, smaller fish lodged in their throats. Most fossils of this genus are from the Tertiary era, Green River Formation in Wyoming, though relatives of this genus are known to range throughout Asia and New Zealand. Mioplosus is also believed to be related to the modern, pike-perch of the genus Sander (Stizostedion).

It comes from the coveted 18 inch layer of the Green River Formation which produces darker and more detailed fish than the majority on the market. The rock from this layer is much harder and more durable. This layer is typically collected at night using low-angle light to see the bump in the rock that the backbone creates. They then cut these fish out and take them to a lab where the fish, which may be up to an inch under the surface of the rock, are meticulously extracted under microscope with hand tools.

A view of the 18 inch layer of the Green River Formation at the Lindgren quarry near Kemmerer, Wyoming.
A view of the 18 inch layer of the Green River Formation at the Lindgren quarry near Kemmerer, Wyoming.

50 million years ago, in the Eocene these fish thrived in Fossil Lake fed by Uinta and Rocky Mountain highlands. The anoxic conditions at the bottom of Fossil Lake slowed bacterial decomposition, prevented scavengers from disturbing corpses, and most interestingly, suffocated creatures that ventured into the oxygen-starved aquatic layer. The result is a miraculous exhibition of Eocene biota in a subtropical, aquatic community within sycamore forests teeming with creatures such as freshwater stingrays, dog-sized horses, menacing alligators, early flying bats, and one of the first primates.

A view of one of the commercial quarries where fossils from the Green River Formation are collected.
A view of one of the commercial quarries where fossils from the Green River Formation are collected.
DETAILS
SPECIES
Mioplosus labracoides
LOCATION
Kemmerer, Wyoming
FORMATION
Green River Formation
SIZE
10.6" long on 15.8 x 9" rock
CATEGORY
ITEM
#179313
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