A SURVEY OF NON-TOOTH CHONDRICHTHIAN HARD-PARTS FROM THE LOWER NAVESINK FORMATION (MAASTRICHTIAN) IN MONMOUTH COUNTY, NEW JERSEY

The lower Navesink Formation in Monmouth County, New Jersey contains an assemblage of rare non-tooth chondrichthian hard parts. These hard parts occur directly above a prominent disconformity separating the Campanian and Maastrichtian stages of the upper Cretaceous. Although difficulties arise in associating isolated chondrichthian hard parts with individual chondrichthian species, these hard part specimens occur within the same stratigraphic horizon as chondrichthian teeth, and this association, coupled with analogy to modern relatives, provides clues to hard part origin. From this horizon we document: 1) fin spines and cephalic hooks from the extinct shark Hybodus; 2) vertebral centra from lamniform and squatinaform sharks and from myliobatiform rays; 3) calcified Meckel's, palatoquadrate and vertebral cartilage; and, 4) dermal denticles tentatively derived from the rays Brachyrhizodus wichitaensis and Rhombodus levis. Examples of these specimens provide unique insight into aspects of fossil chondrichthian anatomy not documented by teeth and not often preserved in upper Cretaceous sediments.