The Cartilaginous Fish
(Chondrichthyes)
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This page deals with the fossilized teeth and other remains of sharks, rays skates, and their distant cousins the ratfish (chimeras).
Shark teeth are by far the most common vertebrate remains in the Atlantic Coastal Plain and at Big Brook. This is due to the
construction and numbers of teeth produced. The root and the core of the tooth is made of true bone, the only true bone in an
otherwise all cartilaginous skeleton. The enamel of the tooth is made of the hardest organic substance known to man. This
makes the tooth highly resistant to breaking and dulling during life but also to stream abrasion after fossilization. Also shark teeth
are prolific in a singular jaw. When a tooth is lost or broken during a meal it is replaced with the one behind it in about 7 days.
This also keeps sharp teeth available. Each working tooth has at least 7 more replacements behind it that are in various stages
of development. There are usually about 70 such rows in an average jaw. So most sharks go through at lest 10,000 teeth in
their lifetime. Coupled with their durability and the numbers that were being produced, this is why sharks teeth are the most
prolific vertebrate find.
The shark teeth found at Big Brook have been researched and compared to other localities of similar age and with a few
exceptions, there is little doubt as to the assignments of species. Other material such as dermal scutes, are harder to identify. As
with most vertebrates found here, a complete skeleton is very rare. The skeletons of most cartilaginous fish did not fossilize at
all. So most of the time isolated finds are what paleontologists are forced to work with. By comparing the fossil to other
localities of around the same age, they may be able to make an educated guess as to what went with what. This was and still is
the best used means of identifying isolated material.