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Gnathostome diversity comprises roughly 60,000 species, which accounts for 99% of all living vertebrates, including humans. Most gnathostomes have retained ancestral traits like true teeth , a stomach , [ 2 ] and paired appendages (pectoral and pelvic fins, arms, legs, wings, etc.). [ 3 ]
A study of the arthrodire Compagopiscis published in 2012 concluded that placoderms (at least this particular genus) likely possessed true teeth contrary to some early studies. The teeth had well defined pulp cavities and were made of both bone and dentine. However, the tooth and jaw development were not as closely integrated as in modern ...
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.
They are noted for their denticle whorls - oropharyngeal denticles that lined their branchial bars - which are thought to be homologous with other, later gnathostome teeth. In this sense, Loganellia may possess the earliest known dental structures related to modern teeth, and would have evolved in the throat, rather than through dermal ...
This is because the conodont animal was soft-bodied, thus everything but the teeth was unsuited for preservation under normal circumstances. These microfossils are made of hydroxylapatite (a phosphatic mineral). [18] The conodont elements can be extracted from rock using adequate solvents. [19] [20] [21] They are widely used in biostratigraphy.
From Hershey's to Toblerone, here are eight of the oldest candy bars in the world, all of which are still around and available for purchase today. Lindt chocolate. 1. Lindt. $7.82 at Walmart.
Oil pulling is an ancient oral health practice that's popular on social media for its supposed benefits. Experts explain how oil pulling works and what the science says. Oil pulling is going viral ...
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.