Gli squali fossili
Megasqualus is known only from isolated teeth found in Paleocene and Eocene sediments of Europe and North America. The teeth are large by squalid standards, according to Cappetta (1987) reaching one cm in width. Otherwise, the teeth are very similar to those of the extant genus - Squalus. Rows of these teeth create a long cutting edge, serving as Compagno (1987) calls it, a clipping function. The living dogfish sharks have a circumglobal distribution, which, depending on species, ranges from tropical to boreal. They are bottom dwellers that can be found from intertidal waters to 900 meters. The primary prey is bony fishes, but their diet includes various invertebrates.
As with the teeth of Squalus,
it is the prominent, basally extended apron which "jumps out" when these
teeth are first viewed. A laterally elongated, distally direct cusp is
accompanied by a convex heel or shoulder. Unlike Squalus, the teeth of
Megasqualus orpiensis (WINKLER 1874) have a serrate heel, and a mesial
cutting edge that often bears serrations to some extent. (Note the numerous
elongated foramina on the root face and strong lingual protuberance.) Kent
(1994) reports these teeth as being found in both Paleocene Formations
of the Chesapeake Bay area - the Brightseat and Aquia. Cvancara & Hoganson
(1993) reported this species from the Paleocene of the Dakotas. The accompanying
image is an Eocene specimen from the Nanjemoy.
Cvancara, A. & Hoganson, J, 1993. Vertebrates of the Cannonball Formation (Paleocene) in North and South Dakota. Journal of Vertebrate Paleontology, 13(1) pp 1-23.
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