BONNERICHTHYS GLADIUS (OSTEICHTHYES) FROM THE CRETACEOUS OF THE ATLANTIC COASTAL STATES

The large Late Cretaceous fish Bonnerichthys gladius, now interpreted to have been a plankton feeder, would presumably have thrived in an area with access to open oceanic environments, such as the Atlantic coast. Two specimens, previously cited but not described in detail, tend to confirm this suggestion. The more enigmatic of the two is a fragmentary scapulocoracoid from the Campanian of New Castle County, Delaware. It is anatomically consistent for a referral to Bonnerichthys, to the extent that the scapulocoracoid is known, in both articulations and proportions. However, it is of relatively small size.

The more diagnostic specimen is a highly characteristic fin spine fragment from the Maastrichtian of Monmouth County, New Jersey. It may be geologically later than any other specimen of Bonnerichthys gladius thus far reported. This suggests persistent survival of such a highly pelagic plankton feeder in proximity to the open ocean. Presumably the species survived until the mass extinction event at the end of the Cretaceous Period.