SCAVENGING BY SHARKS OF THE GENUS SQUALICORAX IN THE LATE CRETACEOUS OF NORTH-AMERICA

Diverse sources and types of evidence indicate that common Cretaceous selachians of the genus Squalicorax were the preeminent scavengers of vertebrate carcasses during Santonian and Campanian ages of the Late C retaceous. Evidence considered comes from the eastern Gulf Coastal Pla in and Western Interior of the United States. Direct, material evidenc e of scavenging includes a decayed mosasaur vertebral centrum and a ha drosaurian dinosaur metatarsal, each containing a Squalicorax tooth ev idently embedded after the host's death. Abundant implicit evidence of scavenging includes Squalicorax bite marks and Squalicorax teeth asso ciated with numerous marine tetrapod and fish remains, and at least on e additional dinosaur Many of these bite marks and tooth associations are with predaceous tetrapod taxa, well beyond the reasonable prey siz e of Squalicorax species. Inference of scavenging by Squalicorax is al so based on comparative counts of selachian teeth in Upper Cretaceous deposits in the eastern Gulf of Mexico. Typical shark-tooth assemblage s are dominated by lamnoid teeth, but at two well-studied Localities c ontaining the associated remains of large vertebrate carcasses, few sh ark teeth are found except those of Squalicorax, implying that these w ere shed during scavenging activity. Although it is not definitively p roven that Squalicorax was an. obligate scavenger, the longevity and c osmopolitan distribution of the genus may relate to this primary feedi ng strategy.