QUALITY Iniopterygian “Flying Shark” Bear Gulch Fish Fossil
"Part & Counterpart"
Time: Mississippian (~320 m.y.a.)
mm = 1 inch):Fish: 68 mm long by 35 mm wide Matrix: 170 mm by 130 mm and
65 by 115 mm pair
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 specimen is a member of the little-known and poorly understood
Iniopterygii. Most have yet to be
described. They are collectively characterized by large pectoral
fins mounted high on the body and denticulated bony plates on the
head and jaws. They lived from the Devonian into the Carboniferous.
The elongated pectorals had denticles along the leading edge which
may have had a role in mating. They are thought to have been able
to move their pectorals in a vertical plane,”flying”
through the water much like modern-day penguins. Some researchers
believe tey were capable of escaping predators by gliding the way
the flying fish Exocoetus does today. The closest modern-day relatives
of the Iniopterygii are the Chimaeras (Chimaeriformes) also known
as ghost sharks or rat fish. This is an excellent part/counterpart
example preserved in dorsal aspect.
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