Until the 16th century,[4] sharks were known to mariners as "sea dogs".[5] The etymology of the word "shark" is uncertain. One theory is that it derives from the Yucatec Maya word xok, pronounced 'shok'.[6] Evidence for this etymology comes from the OED, which notes the name "shark" first came into use after Sir John Hawkins' sailors exhibited one in London in 1569 and used the word "sharke" to refer to the large sharks of the Caribbean Sea.
An alternate etymology states that the original sense of the word was that of "predator, one who preys on others" from the German Schorck, a variant of Schurke "villain, scoundrel" (cf. card shark, loan shark, etc.), which was later applied to the fish due to its predatory behaviour.[7]
Evolution
Photo of dozens of yellowish fossilized teeth, the teeth are of various sizes and are spread out randomly on a flat black surface.
A collection of Cretaceous shark teeth
See also: Evolution of fish
Evidence for the existence of sharks dates from the Ordovician period, over 450–420 million years ago, before land vertebrates existed and before many plants had colonized the continents.[1] Only scales have been recovered from the first sharks and not all paleontologists agree that these are from true sharks.[8] The oldest generally accepted shark scales are from about 420 million years ago, in the Silurian period.[8] The first sharks looked very different from modern sharks.[9] The majority of modern sharks can be traced back to around 100 million years ago.[10] Most fossils are of teeth, often in large numbers. Partial skeletons and even complete fossilized remains have been discovered. Estimates suggest that sharks grow tens of thousands of teeth over a lifetime, which explains the abundant fossils. The teeth consist of easily fossilized calcium phosphate, an apatite. When a shark dies, the decomposing skeleton breaks up, scattering the apatite prisms. Preservation requires rapid burial in bottom sediments.
An alternate etymology states that the original sense of the word was that of "predator, one who preys on others" from the German Schorck, a variant of Schurke "villain, scoundrel" (cf. card shark, loan shark, etc.), which was later applied to the fish due to its predatory behaviour.[7]
Evolution
Photo of dozens of yellowish fossilized teeth, the teeth are of various sizes and are spread out randomly on a flat black surface.
A collection of Cretaceous shark teeth
See also: Evolution of fish
Evidence for the existence of sharks dates from the Ordovician period, over 450–420 million years ago, before land vertebrates existed and before many plants had colonized the continents.[1] Only scales have been recovered from the first sharks and not all paleontologists agree that these are from true sharks.[8] The oldest generally accepted shark scales are from about 420 million years ago, in the Silurian period.[8] The first sharks looked very different from modern sharks.[9] The majority of modern sharks can be traced back to around 100 million years ago.[10] Most fossils are of teeth, often in large numbers. Partial skeletons and even complete fossilized remains have been discovered. Estimates suggest that sharks grow tens of thousands of teeth over a lifetime, which explains the abundant fossils. The teeth consist of easily fossilized calcium phosphate, an apatite. When a shark dies, the decomposing skeleton breaks up, scattering the apatite prisms. Preservation requires rapid burial in bottom sediments.
