Shark tooth
[1] There are four basic types of shark teeth: dense flattened, needle-like, pointed lower with triangular upper, and non-functional.
Sharks are a great model organism to study because they continually produce highly mineralized tissues.
[3] Although sharks constantly shed their teeth, factors such as water temperature affect the turnover rate.
[7] The most ancient types of shark-like fish date back to 450 million years ago, during the Late Ordovician period, and are mostly known by their fossilized teeth and dermal denticles.
The combination of teeth entails serrated edges to cut the larger prey into smaller portions in order to easily swallow the pieces.
(Example: teeth from Otodus auriculatus as it evolved into O. angustidens) are difficult to definitively identify as coming from either species.
A commonly referred to transition is the evolution of Isurus hastalis, the extinct giant mako, into the great white shark, Carcharodon carcharias.
[13] These teeth are in extremely high demand by collectors and private investors, and they can fetch steep prices according to their size and deterioration.
[13] The sediment that the teeth were found in is used to help determine the age of the shark tooth due to the fossilization process.
[16][17] Fossilized shark teeth can often be found in or near river bed banks, sand pits, and beaches.
These teeth are typically worn, because they were frequently moved and redeposited in different areas repeatedly before settling down.
[13] Near New Caledonia, up until the practice was banned, fishermen and commercial vessels used to dredge the sea floor for megalodon teeth.
[15] To collect information on basic-life history and get dispersal estimates of a shark tooth, molecular-based technology is very efficient.
[23] In order to reduce effects of deterioration in the teeth, it is useful to sample only the surface of the enameloid of the tooth for this specific research.
The oldest known records of fossilized shark teeth are by Pliny the Elder, who believed that these triangular objects fell from the sky during lunar eclipses.
Glossopetrae were commonly thought to be a remedy or cure for various poisons and toxins; they were used in the treatment of snake bites.
Due to this ingrained belief, many noblemen and royalty wore these "tongue stones" as pendants or kept them in their pockets as good-luck charms.
[28] He mentioned his findings in a book, The Head of a Shark Dissected, which also contained an illustration of a C. megalodon tooth, previously considered to be a tongue stone.
[34] It is reported that the rongorongo tablets of Easter Island were first shaped and then inscribed using a hafted shark tooth.
