Ammonites in the Juana
Lopez and Lower Ferron Sandstone Members of the Mancos Shale in East-Central Utah
Cobban and Hook 1980
From the Juana Lopez Member, this specimen is 533mm dia.
Ammonite fossils are locally common in the Lower Ferron Sandstone and
Juana Lopez Members of the Mancos Shale. These units outcrop from
south of Last Chance Wash near Fremont Junction on I-70 north to
Wellington, south to Green River, and east to the Colorado border.
Prionocyclus macombi Meek 1876
from the Juana Lopez member, This one is 335mm dia.