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Abstract

Phylum Chordata, subphylum Vertebrata

Vertebrates range from Cambrian to Recent (initially as jawless fish)

  • Jawed vertebrates — Early Silurian-Recent

  • Terrestrial vertebrates — (Late Devonian) Carboniferous-Recent

  • Reptiles — Carboniferous-Recent

Early vertebrate remains (Cambrian-Silurian) are confined to marine settings; subsequent diversification led to expansion into virtually all environments from polar to tropical and from terrestrial to abyssal marine. Most vertebrate remains in carbonate rocks are fish scales and teeth from lacustrine or marine settings; bone and tooth material from other groups, however, also can be found on occasion.

Vertebrate remains are rare but can sometimes be found concentrated by wave or current action or by nonsedimentation of other materials at hiatus surfaces.

Bones and teeth are largely composed of organic proteins (mainly collagen) and calcium phosphate (carbonatehydroxylapatite, sometimes termed collophane when it is microcrystalline). The interior parts of bones (the cancellous portions) have a spongy texture that commonly is filled with precipitated cement (most commonly carbonate, silica or phosphate) during diagenesis.

Vertebrate organisms have an enormous range of external morphologies, but all have a vertebral column and other hard parts (other bones, teeth, or scales) that typically disarticulate upon death and can become scattered into carbonate and noncarbonate sedimentary deposits.

Vertebrate debris can range in size from less than a mm to well over 1 m, but is typically in the mm to cm size range.

Most bones share common features: a dense, smooth, outer or cortical part, and an interior composed of multiple layers of porous or spongy, cancellous material (in life, the porous areas are occupied by marrow).

Teeth are constructed of three layers: a pulpy cavity, a covering of dentine, and where the tooth is exposed, an additional covering of enamel.

Dentine is relatively hard and dense and has a mineral content of about 75%; enamel is even denser and is almost 98% hydroxylapatite.

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