Sarcopterygii, Subclass, Coelacanthimorpha, Order Coelacanthiformes,
Time: Mississippian (~320 m.y.a.)
Fish: 120 mm long
Site: Bear Gulch Limestone, Heath Shale Formation, Fergus County,
The Bear Gulch Limestone is a Lagerstätte Fossil Site of some
70 square kilometers in extent and 30 meters depth that has been
a source of one of an extremely diverse assemblage of fish fossils.
Some 110 species having been described over the past 30 years. Most
were new to science, and provided a new window into the marine environment
of Mississippian times. Fine preservation of both fish and invertebrates
is exhibited of these deposits, ostensible due to an anoxic depositional
environment. This specimen is a coelacanth known as Caridoscuctor
(“shrimp eater”), and is well-represented in the Bear
Gulch deposits. Specimens found range from 30 mm to 250 mm in length.
They exhibit sexual dimorphism, with larger, more robust females
and smaller, more gracile males, a characteristic also seen in the
modern coelacanth Latimeria. The species Caridosuctor populosum
died out during the Lower Carboniferous. The preservation of this
specimen is exquisite.