Hoploscaphites nicolleti
Fox Hills Formation UNAZ Trail City Mbr.
Upper Cretaceous (Maastrichtian)
Dewey County, South Dakota

This specimen is complete concretion containing multiple macroconch forms of H. nicolleti. There are at least 9 ammonites in the nodule and perhaps more. The preservation is typical of the Upper Nicolleti Zone with original shell and iridescence. This is a wonderful display piece and is instructive as to the mode of occurrence for these ammonites.
The macroconchs of H. nicolleti are characterized by fine, dense ribbing on the anterior two-thirds of the body chamber, ribs, and peristome with a strong adoral projection on the venter. Ventrolateral tubercles are found mostly on the posterior part of the body chamber and may or may not appear on adjacent parts of the phragmocone. The microconch body chamber is more compressed with a broad flat umbilical shoulder bordered by bullae. It has ventorlateral tubercles as seen on the macroconch.
The Trail City Member of the Fox Hills Formation is a light-grey clayey silt that forms the lower 65 - 210 feet of the formation in the type area. It contains several limestone concretion zones with a rich ammonite and pelecypod fauna.