Hoploscaphites nodosus with Baculites compressus
Pierre Formation
Upper Cretaceous (Campanian)
Pennington County, South Dakota

This is an excellent example of the macroconch form of H. nodosus. The specimen has the original shell and it is iridescent on the living chamber. This specimen has very well defined nodes typical of the species. It is complete all the way to the aperture. The specimen some slight restoration of several nodes and one small spot on the phragmocone. The ammonite is just over 3 inches. This specimen is prepared on its original limestone concretion matrix and has 5 associated sections of Baculites compressus. There is also a partial phragmocone of another Hoploscaphites. This is a dramatic display specimen and would be a fine addition to any ammonite collection.
H. nodosus is comparatively large for this family of ammonites. The species is robust with a somewhat long shaft on the body chamber and a moderate recurved aperture or hook. The umbilical walls are well rounded to steep. Ribs are broad, prominent, and fairly straight with some bifurcation and bending. The most distinguishing characteristic for the species in both micro and macroconch forms is its narrow, slightly rounded flank and a broad, rounded venter. It has a prominent row of tubercles along the ventrolateral shoulder and another near the middle to the dorsal edge of the flanks
H. nodosus ranges from the Didymoceras cheyennense through the Baculites cuneatus Range Zone and is found throughout the Western Interior Seaway.