In the Upper Cretaceous, the skates followed their order-mates, the Rhinobatoids, into the fossil record. Compared with guitarfishes, the skates have more broadly expanded discs, less stout tails and reduced or absent caudal fins. The pelvic fins are expanded (may be divided) and the rostrum generally longer. The skates can be further characterized by their numerous thorns and the lack of a caudal stinging spine. The teeth are small and arranged in numerous files.

Identifying isolated Lee Creek skate teeth with any degree of certainty may not be possible. In today's oceans, some 230 species are known to exist - most with relatively similar tooth morphologies. Facing collectors of the Lee Creek fauna are challenges. The typical skate tooth shows marked sexual dimorphism of the crown (high cusped in males) but unlike other elasmobranch teeth I've studied, the variations sometimes seem to carry over to the roots as well.

Compounding these odontological challenges is the similarity of teeth between species and subgenera. Otherwise similar extant skates have been (re)classified by their temperature and depth preferences. Without proper documentation of a specimen's stratigraphic position, any assignments, even to genus could be questioned.

As the study of living species continue, the family to which a genus should be ascribed has not even been resolved. It would seem that teeth belonging to this sub-order can most accurately be described as a skate. If a Latin name is preferred, I'd recommend "Raja" sp -- it would better highlight the usage of the generic concept of the genus as used in paleontology when identifying isolated teeth.

Lee Creek Skates

Despite these obstacles, it is possible to make educated or at least semi-educated guesses at times. Two Miocene depositional environments of the Albemarle Embayment are reflected at Aurora. The Lower Miocene of the Pungo River Formation is thought to have been a subtropical environment with a strong thermocline providing much cooler temperatures nearer the bottom. The lower two units of the Yorktown Formation are considered Upper Miocene and the waters were warm temperate. The Yorktown's waters would have been similar to those found today off the Carolinas. Most of the Yorktown shark teeth are thought to be ascribable to extant species, and this propensity would likely be similar with the rays.

Skates are a much more common element of the batoid fauna in the Yorktown which corresponds well with the cooler waters. With this greater abundance and the likelihood we'd be dealing with extant species, I will begin by addressing those specimens. When Bigelow & Schroeder (1948) inventoried these fish, they listed 29 species for the western North Atlantic, but only ten would be likely candidates for Yorktown waters. I am not excluding species from other areas of the Atlantic, merely considering the more likely donors.

The species that have the best shot at being represented are: Breviraja plutonia & spinosa, Dactylobatus armatus, Raja (Amblyraja) radiata, R. (Dipturus) laevis, R. (Leucoraja) erinacea, garmani & ocellata, and R. eglanteria. The Pungo River teeth will be much more difficult to work with and better compared with their Yorktown counterparts.

Lee Creek Skate Teeth

As a percentage of the batoid teeth recovered, skate teeth are seven times more common in the Yorktown than in the Pungo River. They have been broadly separated by the author into three type-groups: "F" (unnotched root lobes), "K" (notched root lobes) and "V" (other). Terminology

F-Type Teeth. (Figures 1 & 2) Excluding specimens from the DPW site, the vast majority of teeth described as "F" come from the Yorktown and represent its most common type of skate tooth. These teeth have been sub-grouped by other characteristics (i.e., foramina pattern) and the illustrated example (F3) represents one of the more common variations. The illustrated example measures: height = 2.6, width = 2.5 & depth = 3.3 mm. It is suspected that more than one species may be represented in the type "F" tooth group. Also illustrated is what appears to be a female F-type tooth. This specimen measures: height = 1.6, width = 2.0 and depth = 2.0 mm.

Fig. 1) "Raja" sp Type "F3" - [96-JAB-TGA-256-S08] - male

Fig. 2) "Raja" sp Type "F1" - [96-JAB-TGA-142-S13] - female

K-Type Teeth. (Figure 3) From mine samples, these teeth are twice as abundant in the Pungo River but the sample size is so small, that this percentage is of questionable value. (They are the predominant type from the DPW site.) The illustrated tooth-style (K5) represents over half the examples of the K-type tooth. The illustrated K5 measures: height = 1.8, width = 2.3 & depth = 2.1 mm. Since completing this drawing, undamaged specimens have been found.

There appears to be at least two species represented within this group. Two specimens have a foramen in the external notches of each root lobe and one has an unusual labial notch with a foramen on each lobe.

Fig. 3) "Raja" sp Type "K5" - [96-JAB-BC-101-S48] -male

V-Type Teeth. Certain teeth fall outside the criteria established for the above two types. Some of these are likely tooth position variations which are misleading; however, there are a number of small (1 mm) teeth with poorly developed roots -- these may very well represent another species. Terminology

Fig. 4 "Raja" sp Histological cross-section, Herman, et al. (1994 & 95) provide the tooth vascularization of various genera and sub-genera. The illustrated specimen 96-JAB-TGA-391-S23 is an F-type tooth and compares favorably with the vascularization patterns of R. (Dipturus).