Abstract--Damage displayed by 18 of 954 relatively mature (>35 mm diameter) specimens of Gonioloboceras goniolobum
 (Meek) from North American Midcontinent Upper Carboniferous sediments is interpreted to be bite marks caused by
condrichthyans and other fish, particularly the symmoriid shark Symmorium reniforme. lt is likely that these and other
predators regularly preyed on Gonioloboceras goniolobum because all of the analyzed specimens of Gonioloboceras
exhibit some evidence@ of unrepaired damage, including broached camerae and missing body chambers.  Two new characteristics utilized with caution to detect predatory events on ammonoids are raised oval or circular pedestals on
internal molds and the breakage and temination of septa in conjunction with a broken external shell.  When sufficient
damage to the Gonioloboceras conchs occurred during predatory attacks, the broached camerae flooded, the conch
became negatively buoyant, and it sank in the vicinity of the attack.  When preserved, these conchs form a variable
component of an autochthonous fossil accumulation that can include numerous other cephalopod taxa, which also were
probably subjected to predatory attacks.  Other, bot not all, ammonoid accumulations in the fossil record form similar
autochthonous deposits, or even autochthonous portions of mixed deposits.