Gli squali fossili
Members of this genus are relatively large (to 3.6 meters), little known, bottom dwelling, deepwater sharks reported from scattered locales in temperate and tropical waters. Compagno (1984) included two species in his FAO listing and noted they feed on small bony fishes, squid & shrimp. The grasping dentition lacks the crushing posterior teeth found in the genus Carcharias.
O. ferox (RISSO, 1810), the Smalltooth sand tiger has been reported from isolated locations (Eastern Atlantic, Pacific, Indian Oceans & Mediterranean), preferring somewhat deep waters of continental and insular shelves (15 - 400 m). This species' teeth bear 2- 3 pairs of lateral cusplets and the dentition includes 3 - 5 rows of intermediate teeth. O. noronhai (MAUL, 1955), the Bigeye sand tiger, prefers deeper waters (600-1000 m) of continental and insular slopes. It's known from isolated locales in Atlantic and Indian Oceans. In this species, the teeth have a single pair of lateral cusplets and there is a singular file of intermediate teeth.
Cappetta (1987) pointed out that the cusp of these teeth are sharp and lateral cusplets (2 on anterior teeth, up to 3 on laterals) high. The lingual face is convex and bears an incomplete (basally) cutting edge. He includes four species known from the fossil record: O. ferox [Lower Pliocene of Italy], O. aculeatus (CAPPETTA & CASE, 1975) [Upper Campanian of New Jersey], O. speyeri (DARTEVELLE & CASIER, 1943) [Paleocene of Africa] and O. winkleri LERICHE, 1905 [Lower - Middle Eocene of the Anglo-Franco-Belgian basin and Eocene of Maryland].
Ward & Wiest (1990) reported
O. winkleri from the Paleocene [Danian &Thanetian] and Eocene [Ypresian]
of Maryland and Virginia. Kent (1994) noted that O. aculeatus had been
reported from the Marshalltown, Mount Laurel & Severn Formations of
New Jersey, Delaware and/or Maryland. He noted that the teeth of this species
were up to 1.5 cm in height and bore large lateral cusplets, the second
nearly as large as primary. He noted that the teeth of O. winkleri were
higher (to 2.5 cm) and secondary cusp smaller than the primary. Teeth of
this genus (O. aff ferox) have been found (rarely) at Lee Creek (Mio-Pliocene
of North Carolina).
© 1999-2013 www.squali.com di Antonio Nonnis