Clioscaphites from the Emery Sandstone

The Emery Sandstone

    The Emery Sandstone as exposed in western Emery County, Utah consists of 4 or 5 thin sandstone beds that thicken rapidly sub-surface to the west.  Cephalopods preserved in the formation, mostly as internal molds, include the Nautiloid Eutrephoceras sp., and the ammonites Placenticeras syrtale, Baculites codyensis, and Clioscaphites vermiformis in the lower beds and Desmoscaphites bassleri in the uppermost bed.  Desmoscaphites bassleri Reeside, 1927, is an Index Fossil for the Upper Santonian (Upper Cretaceous), Clioscaphites vermiformis (Meek & Hayden, 1862), for the Middle Santonian, and C. saxitonianus (Mclearn, 1929) for the Lower Santonian.

    The trouble with finding only a few fossils in a few beds is that intermediates always seem to creep into the section.  The main difference between C. vermiformis and the underlying C. saxitonianus is the strength of the sculpture, pointed tubercles in C. vermiformis, and insipient nodes in C. saxitonianus. The lobe of the suture is another difference, being trifid in C. vermiformis and mostly bifid in C. saxitonianus, but rarely preserved in Emery fossils because the phragmocones are usually crushed.

    Below are photos and 3D models of a couple of fossils from the lower Emery Sandstone (Garley Canyon Beds).  The upper photos show a typical C. vermiformis with its strong sculpture and pointed tubercles. The lower photos show a specimen from the lowest bed of the Emery, still with strong sculpture but without a pointed tubercle, more of a strong 90° rib.  The sculpture on the lower specimen is stronger than typical C. saxitonianus, even stronger than C. saxitonianus var. keytei Cobban, 1952 (which by itself could be a new species).  Not being one to split, it's probably best to leave it in C. vermiformis for now and just consider it an intermediate until more specimens or one showing the suture can be found.

Clioscaphites vermiformis.  Specimen, left, 3D Model, right.  From a sandstone bed in the middle of the Emery Sandstone.

Clioscaphites ?vermiformis, Specimen, left, 3D model, right.  From the lowest sandstone bed in the Emery Sandstone.