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Acanthodii

Acanthodii  

Class of primitive, fossil fish that had a true bony skeleton, a heterocercal tail fin, a persistent notochord, ganoid scales, and stout spines in front of the fins. The acanthodians lived from the ...
Heterostraci

Heterostraci  

(superclass Agnatha)Oldest known vertebrate order of jawless, heavily armoured fish-like forms, ranging from the Upper Cambrian to the Devonian. The dermal plates of the body lacked true bone cells ...
phosphorite

phosphorite  

A sedimentary rock rich in phosphate, usually in the form of carbonate hydroxyl fluorapatite (Ca10(PO4CO3)6F2–3). Phosphorites occur as nodules and crusts formed in oceanic areas where sedimentation ...
skeletal material

skeletal material  

In most vertebrates the skeleton is made from bone (calcium phosphate); among invertebrates it is more varied. Calcite or aragonite in various forms is common in such groups as the brachiopods ...
Teleostei

Teleostei  

The major superorder of the Osteichthyes (bony fish), containing about 20 000 species. Teleosts have colonized an extensive variety of habitats and show great diversity of form. The group includes ...

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