Jeletzkytes nebracensis
Fox Hills Formation POAZ Trail City Mbr
Upper Cretaceous (Maastrichtian)
Corson County, South Dakota

Here is large beautiful specimen of a complete Jeletzkytes nebrascensis. The shell on the living chamber has good iridescence. The very detailed suture pattern is visible on the inner whorls. This is the macroconch form. The specimen is prepared in its original concretion matrix. The ammonite is over 16 cm across. This is a classic example from the locality. There is a small chip from damage while collecting but there is no restoration or repair.
The macroconch of this species is compressed and the last whorl is markedly higher than wide. The phragmocone is conspicuously tuberculate with strong ventrolateral tubercles and five to seven rows of weaker flank tubercles which commonly extend onto part or all of the body chamber. The microconch is variably tuberculate commonly with double row of umbilical tubercles or bullae.
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 faua.