Superb Kalops monophrys Paleozoic Fossil Fish

from Heath Shale Bear Gulch Lagerstätte

Kalops monophrys

Class Actinoptergyii, Order Paleonisciformes

Geological Time: Mississippian (~320 m.y.a.)

Size (25.4 mm = 1 inch): Fish fossil is 129 mm Matrix: 225 mm by 270 mm

Fossil Site: Heath Shale Formation, Bear Gulch Limestone, Fergus County, Montana

Kalops monophrysDescription: The Bear Gulch Limestone is a deposit of some 70 square km in extent and 30 m in depth that has been a source of one of the most diverse assemblages of fossil fish with some 110 species having been described over the past 30 years. Most were new to science, and provided a unique view of the marine environment of Mississippian times. Fine preservation of both fish and invertebrates is a hallmark of these deposits, presumably due to an anoxic depositional environment. This fish is a palaeoniscoid of the genus Kalops. There are two known genera, and this one, Kalops monophrys, is distinguished by larger size, more caudal fin rays, and larger ganoine ridging to the bones of the head. . The detail for a specimen nearly a third of a BILLION years old is remarkable. Note particularly the detail to the skull, vertebral column, and tail as well as the characteristic scale pattern.

Reference: J. Paleont. 76 (6), 2002, pp 1014-1028.

click to enlarge fossil pictures

Kalops monophrys

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