Gracile form of
P. wyomingensis on left was
found associated with
Scaphites cf. S. whitfieldi east of
Clawson. The ammonite on the right is the robust form of
P.
novimexicanus found with
S. whitfieldi high in the Juana
Lopez Member S.E. of Green River.
P. wyomingensis has a
double row of ventro-lateral nodes while
P. novimexicanus has a
single row, with a groove on each side of the keel.
See parts of a crushed P. novimexicanus?
here
Ammonites from the P. novamexicanus Biozone
Prionocyclus wyomingensis Meek 1876
Gracile form on left, robust form on right, both associated with
Scaphites
cf. S. ferronensis . These ammonites can be found all along
the outcrop of the Juana Lopez Member from east of Ferron, around the
north end of the San Rafael Swell, to the Colorado border.
See a large adult P. wyomingensis
here
Ammonites from the P. wyomingensis Biozone
Prionocyclus macombi Meek 1876
Gracile form on left, robust form on right. From the Juana Lopez
Member S.E. of Green River. P. macombi has a single row of
ventro-lateral clavi and low flattened ribs.
See a large adult P. macombi here
Ammonites from the P. macombi Biozone
Prionocyclus hyatti (Stanton) 1893
Gracile form on left, robust form on right. Found in the lower
Ferron Sandstone Member near Mounds. P. hyatti has a much wider
umbilicus than the other prionocyclids.
Ammonites from the P. hyatti Biozone
