Ibexian Series, Tulean Stage
Zone G-1 Cephalopods

These were found near the top of the informal Slope-forming shaly siltstone Member of the Fillmore Formation in a nodular silty shale bed.  The internal molds of the living chamber of orthocones are the most common fossil, most of the phragmocones were probably crushed and all the shell material had been disolved prior to lithification of the shale.


Orthocone body chamber molds
some have burrows between where the shell was, and the mud infill.

Below are 3 views of an Ellesmerocerid? phragmocone from the same beds.

The phragmocone must have been partially damaged and filled with sediment prior to the rest of it being crushed and  the shell material dissolved.  This specimen seems to be an endogastric cyrtocone, but it may just be a distorted orthocone.

crushed side


uncrushed side


end view showing the large ventral siphuncle

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