During the Jurassic, a couple of elasmobranch orders entered the fossil record. For the purposes of this web page, the relevant order is Rajiformes, particularly the suborder Rhinobatoidei (guitarfishes). Later, in the Miocene, at least two of the families of this suborder were represented in the western Atlantic, RHYNCHOBATIDAE (Rhynchobatus) and RHINOBATIDAE (Rhinobatos) -- the earliest batoids.

Members of this suborder retain more primitive (shark-like) characteristics than other batoids; the tail is still strong and both caudal and dorsal fins are present. Unlike the flattened angelshark (Squatina), these and all future rays had pectoral fins fused to the head and their gills were on the ventral surface. Guitarfishes tend to have a short snout, unnotched pelvic fins and small teeth forming a crushing dentition. The crown of these teeth are bulbous and there is a distinct, elongated, (lingual) uvula. Viewed basally, the roots have two lobes which form a triangular profile, narrowing lingually. There is a complete nutrient groove, yet the hemiaulacorhizous characteristic of a basal foramen connecting to lingual foramina is often retained. These foramina are coincidental with the notch that give each lobe its two-part appearance. Terminology

No longer present in the western Atlantic, Rhynchobatus can be found in warm, not very deep waters of the eastern Atlantic, Indian and Pacific Oceans. Cappetta's (1987) description is similar to that of Rhinobatos. He mentions the extant species R. laevis, and the (European) Miocene species R. pristinus. For information on the dentition of this species, see extant Rhynchobatus spp.

In describing the teeth of the former, Cappetta points out several characteristics. The dentition itself is made up of alternating groups of larger (to 5.0 mm) and smaller (2.0 mm) teeth forming a crushing dentition. He describes the crowns as being generally wider than deep with a distinct central uvula. The roots he terms as massive, narrower than the crown, displaced and narrower lingually with a well developed nutrient groove and two centrally placed foramina. Bob Purdy of the Smithsonian indicated that Rhynchobatus was the only rhinobatoid genus positively identified as from Lee Creek.

Fig. 1) Rhynchobatus sp - [95-JAB-BC-604-S52] - hgt 2.8, wid 3.6, dep 3.5 mm

Of personally collected rhinobatoid specimens, over 80% conform with Cappetta's description. The crowns range from 1.8 to 5.2 mm in width, and have been primarily found in Pungo River tailings -- either from the mine or the DPW site in Blount Crossing. Specimens have been recovered from lower Yorktown (unit 2) samples.

Cappetta's description of Rhinobatos teeth is very similar to that of Rhynchobatus. The main difference appears to be the relative lengths of the central and lateral uvulae, which are more pronounced in Rhinobatos. Figure 2 represents one of two specimens that ascribe to his description and are being tentatively identified as Rhinobatos. The root is slightly worn but reasonably complete. For information on the dentition of this species, see extant Rhinobatos spp.

Fig. 2 cf Rhinobatos sp - [96-JAB-BC-302-S03] - hgt 1.6, wid 2.0, dep 1.9 mm