Injuries in a Mysticete Skeleton from the Miocene of Virginia, With a Discussion of Buoyancy and the Primitive Feeding Mode in the Chaeomysticeti

Brian L. Beatty, Alton C. Dooley, Jr.

Injuries in a Mysticete Skeleton from the Miocene of Virginia, With a Discussion of Buoyancy and the Primitive Feeding Mode in the Chaeomysticeti

08-19-2009

A mostly complete skeleton of a mysticete from the Carmel Church Quarry displays some injuries, including a fractured and partially-healed left mandible, previously not reported in any fossil mysticete. The mostly healed nature of this non-union impaction fracture indicates that the animal died a significant amount of time after the injury. Additional injuries of the postglenoid process and left premaxilla, as well as the nature of the impaction fracture in the mandible suggest that the cause of this was some impact from the left anterior aspect. Possible scenarios for how this injury could have happened include intraspecific aggression and, more likely, impact with the seafloor during benthic feeding. The ribs of this individual are heavily osteosclerotic from dorsal to ventral ends, which would suggest that this taxon was a benthic feeder. In comparison with a sample of ribs from fossil mysticetes, it appears that Diorocetus may have been one of the last mysticetes with rib osteosclerosis, a feature possibly primitive to Mysticeti. Although this remains speculative, the presence of osteosclerotic ribs in primitive mysticetes suggests that the feeding mode employed by the earliest Chaeomysticeti was one of benthic feeding.