Causes of damage to brachiopods from the Middle Pennsylvanian Naco Formation, central Arizona

The Kohl Ranch locality in the Naco Formation of central Arizona has yielded an abundant and diverse fauna including eight genera of brachiopods and four of sharks including Cochliodus. The most abundant brachiopod, Composita subtilita, was analyzed for predation damage and of 935 specimens 503 (53.7%) were found to show the type of unrepaired crushing previously attributed to shark predation. Reconstruction of the jaw of Cochliodus, however, suggests that it may have been a selective feeder similar to the modern Heterodontus and unlikely therefore to have left so many damaged but uningested specimens. Evidence from specimens collected in situ suggests that the damage mostly occurred post‐mortem due to the compaction of the sediments and was not due to the sharks who would have comminuted any prey items taken