5.2 Inch Priscacara From Wyoming

Here is a very beautiful and elegant fossil fish from the Green River Formation, a Cockerellites liops. It shows great preservation and detail and is presented nicely in the middle of a rectangularly shaped piece of matrix. The matrix is 10x7 1/2 inches in size and has been back with plywood to give it additional support as the rock itself is fairly thin.

It was collected from the 18 inch layer which produces much darker and well defined fish fossils than the split fish layers. When the fish are found in this layer they are completely covered with rock, which must be professionally removed using hand tools, a process that takes many hours.

Cockerellites liops is a species of extinct temperate bass found in the Eocene aged Green River Formation of Wyoming. It is characterized by a sunfish-like body and its stout dorsal and anal spines. It was originally placed in the Priscacara genus but was moved to the newly created genus Cockerellites by D. Jordan and H. Hanibal in 1923. There is still some debate among researchers about whether this new genus is valid.

Cockerellites is found in large numbers in mid-lake deposits, representing 5 to 20 percent of the fish unearthed, depending on the layer. It is considerably rarer in shoreline deposits, representing only 1 to 2 percent of the fish found. Because of this, Cockerellites is thought to have been a schooling fish. Fossils have been found at a maximum size of about six inches, but they rarely exceed five inches in length.

At first glance, Cockerellites liops has a very similar appearance to the rarer species Priscacara. Size can often be used as a differentiator, since Cockerellites did not exceed 6 inches while Priscacara serrata is typically found in excess of 6 inches. Cockerellites also has more dorsal and anal fin rays than Priscacara and a much smaller mouth.

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