LK Ammonite Schloenbachia
Schloenbachia trinodosa
Duck Creek Fm. (Lower Cretaceous - Albian)
Pecos County, Texas
This specimen is very good quality for the locality and is prepared on matrix. It has a good suture pattern and excellent definition. This is a very complete ammonite with the entire living chamber preserved. It shows a perfectly preserved rostrum which is rarely seen in these specimens. The inner-most whorl is restored.
The genus is small to large-sized with evolute coiling and deep, narrow umbilicus. The inner-most whorls are restored. The whorl section is taller than wide and is subrectangular or squarish. The venter has a low keel and appears squarish rather than rounded. Ribs are straighter and more widely spaced just before the body chamber. Three rows of coarse, equidistantly situated tubercles (nodes) occur: Umbilical, lateral, and ventrolateral. Nodate to clavate ventrolateral tubercles are particularly prominent.
In Pecos County the Duck Creek is about 20 feet thick and contains a prominent ammonite fauna dominated by Schloenbachia and Eopachydiscus. The Duck Creek appears to be conformable to the underlying Kiamichi Formation. The formation is a soft chalky , nodular, whitish, argillaceous limestone rich in fossils. The basal ledge that caps the Kiamichi contains a prominent of fossil oysters and the echinoid Macraster.