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 88 mm long by 18 mm across Matrix: 127 mm by 57 mm
Fossil Site: Heath Shale Formation, Bear Gulch Limestone, Fergus County, Montana
Fossil Code: BGF368
Price: $95.00 - 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 internal structures 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. |
