TITHONIAN STAGE

all those rocks deposited worldwide during the Tithonian Age (152 to 144 million years ago). The Tithonian is the uppermost of 11 stages making up the Jurassic System. The Tithonian's name is derived not from a geographic source but rather from the Greek mythological figure Tithonus, who was the consort of Eos (Aurora), the goddess of the dawn. Numerous ammonite biozones (shorter spans of time characterized by fossil mollusks) are recognized in the Tithonian. The ammonite biozones of Glochiceras lithographicum (which occurs low in the succession) and Pseudovigatites scruposus (occurring high in the succession) are used to correlate the Tithonian with more endemic forms in western Russia (where it is locally named the Volgian Stage) and in England (locally named the Purbeckian Stage). The Tithonian overlies the Kimmeridgian Stage and is itself overlain by the Berriasian Stage of the Cretaceous System.