Exquisitely-Preserved Guildayichthys Mississippian Bear Gulch Fish

Guildayichthys carnegiei

Class Actinoptergyii, Order Guildayichthyformes, Family Guildayichthyidae

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

Size: 58 mm long

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

Guldayichthys carnegieiDescription: 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 fine specimen is a rare example of Guildayichthyformes. The order an family was erected in 2000 to accommodate this unusual taxon which possesses an unusual mixture of primitive and modern characters in the skull bones. Note the detailed rhombic ganoid type scales. Overall, this is an exceptional example of the type, one that is sure to become a keystone of an Carboniferous fossil fish collection.

Also see: Bear Gulch Paleozoic Fish Bear Gulch Fossils

click to enlarge fossil pictures


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