THE FIRST REPORTED FINDING OF CARCHAROCLES AURICULATUS IN THE OLIGOCENE OF GEORGIA

Carcharocles auriculatus (de Blainville, 1818) also referred to as Carcharodon auriculatus (Agassiz, 1843) (Order Galeiformes; Family Isuridae) is one of the least common elements of Eocene- (Case, 1981) and Oligocene-aged marine vertebrate faunas of the Gulf and Atlantic coast (Dockery and Manning, 1986). Although this mega-toothed shark has been reported from the Oligocene of Mississippi (Lesueur, 1828 in Dockery and Manning, 1986) and Florida (Tessman, 1969), the species has not been previously documented in the Oligocene of Georgia. Records exist in the Oligocene of Florida both in the Byram Marl and Suwannee Limestone (Tessman, 1969) and in the Byram Formation of Mississippi (Dockery and Manning, 1986). In both cases, it is very rare. As a species, C. auriculatus is rare in Eocene and Oligocene deposits. A single tooth of C. auriculatus was recovered in situ from the lower Oligocene Bridgeboro Formation in Grady County, Georgia. The Bridgeboro is a rhodolith-rich limestone unit interpreted as a shallow water reef deposit. Primarily, C. auriculatus is found in littoral siliclastic or mixed siliclastic-carbonate sediments. These teeth, generally, show abrasion due to transport. It is assumed that specimens collected in 'pure' carbonates represent normal tooth loss as the individual was in predatory mode. The dimensions (h/w ratio) from the Georgia Oligocene tooth correspond well with the h/w ratio of the Oligocene teeth from Mississippi and the Eocene teeth from Georgia and Mississippi. The overall dimensions of the tooth, (height 44.7 mm; crown height 23.3 mm; width 30.4 mm; average thickness of root 11mm), however are smaller than the samples from the Oligocene of Mississippi. In addition, the specimen from Georgia, shows a preservation type that differs from the other specimens of C. auriculatus. In particular, the root is permineralized with iron oxides. Borings are also evident in the root. Furthermore, the tooth appears not to have been buried rapidly nor does the tooth show signs of transport.