Mississippian Bear Gulch Fish Fossils Association
Fubarichthys copiosus with Unidentified Sarcoptergyian
Time: Mississippian (~320 m.y.a.)
inch): Fubarichthys 72 mm (if straight) Sarcoptyerygian: 61 mm long by
21 mm high Matrix: 165 mm by 280 mm
Heath Shale Formation, Bear Gulch Limestone, Fergus County, Montana
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 plaque shows 2 fish of radically different morphology. The lower
fish is a Palaeoniscoid with a most unusual name: Fubarichthys. The
name was given to the fish because most specimens are found with a
severely disarticulated head (fubar in common parlance means fouled
up beyond all recognition). The upper fish is an as yet indeterminate
Sarcopterygian which goes by the common name “Round Tail”
for obvious reasons. The Sacrcopterygii are known as the lobe-finned
fish, and contain both the Coelacanths and the Lungfish. Unlike other
types of fish, they have a central appendage to the fins containing
many bones and muscles. The group eventually gave rise to the Tetrapods.
Note the exceptional detail to this fine specimen.