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Gnathostomata (/ ˌ n æ θ oʊ ˈ s t ɒ m ə t ə /; from Ancient Greek: γνάθος (gnathos) 'jaw' + στόμα (stoma) 'mouth') are the jawed vertebrates.Gnathostome diversity comprises roughly 60,000 species, which accounts for 99% of all living vertebrates, including humans.
Acanthodii or acanthodians is an extinct class of gnathostomes (jawed fishes).They are currently considered to represent a paraphyletic grade of various fish lineages basal to extant Chondrichthyes, which includes living sharks, rays, and chimaeras.
The three forms of teeth, i.e., coniform cones, ramiform bars, and pectiniform platforms, probably performed different functions. For many years, conodonts were known only from enigmatic tooth-like microfossils (200 micrometers to 5 millimeters in length [ 17 ] ), which occur commonly, but not always, in isolation and were not associated with ...
Entelognathus, a placoderm incertae sedis that combines features of primitive arthrodires with jaw anatomy otherwise only seen in bony fish and tetrapods. Qilinyu , a close relative of Entelognathus that further links Entelognathus as a transitional form between placoderms and other stem-gnathostomes and crown-group gnathostomes.
Diagram of tooth anatomy. Dental anatomy is a field of anatomy dedicated to the study of human tooth structures. The development, appearance, and classification of teeth fall within its purview. (The function of teeth as they contact one another falls elsewhere, under dental occlusion.)
Following on the ideas of Étienne Geoffroy Saint-Hilaire (1818), and studies by Johann Friedrich Meckel the Younger (1820), Carl Gustav Carus (1818), Martin Rathke (1825), and Karl Ernst von Baer (1828), [5] the relationship between the reptilian jaw bones and mammalian middle-ear bones was first established on the basis of embryology and comparative anatomy by Karl Bogislaus Reichert (in ...
The mouth is located just behind the head, after a rostrum, on the underside of the body. It has a pair of cuticular jaws, supplied by strong muscles, and often bearing minute teeth. A "basal plate" on the lower surface that bears a comb-like structure is also present.
In a letter dating to 1713, Edward Hyde, 3rd Earl of Clarendon (known also as Lord Cornbury) from New York reported to the Royal Society learned society of Great Britain that in 1705, a large-sized tooth was found near the side of the Hudson River by a Dutch country-fellow and was sold to New York General Assembly member Van Bruggen for a gill ...