Reticycloceras sp
Class Cephalopoda, Subclass Nautiloidea, Order Nautilida, Family Pseudorthoceratidae
Geological Time: Mississippian (~320 m.y.a.)
Size (25.4 mm = 1 inch): Orthocone fossil is 83 mm long by 20 mm across Matrix: 110 mm by 90 mm and 105 mm by 100 mm pair
Fossil Site: Heath Shale Formation, Bear Gulch Limestone, Fergus County, Montana
Fossil Code: BGF664
Price: Sold
 Description:
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 an orthocone nautilod known as Reticycloceras.
Note the pleated structure to the shell and the siphuncule the
cephalopod used to control its depth preserved in the closeup.
The orthocones derive their name from their essentially straight
shell; some from the Ordovician and Silurian reached lengths of
3 meters. |
