Discinidae
Discinidae is a family in the brachiopod superfamily Discinoidea. Unlike most brachiopods, which have uniformly calcitic or phosphatic shells, modern-day discinids incorporate tablets of silica into their valves. These are covered with vesicles into which the siliceous tablets are cemented, much like a closely packed mosaic, and held together with apatite. These vesicles eventually degrade, but nevertheless still leave an imprint on the shell itself. It has been suggested that this siliceous biomineralisation might also have occurred amongst some of the earliest Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ... brachiopods because similar patterns of shell imprints have been observed amongst them too. References External links Brachiopod families Discinida ...
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Discinida
Discinida is an order of brachiopods comprising the extant superfamily Discinoidea, and the extinct superfamilies Botsfordioidea (early—mid-Cambrian) and Acrotheloidea (early Cambrian–Early Ordovician). It represents a sister taxon to the Lingulids, and is possibly paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ... with respect to the Acrotretoids.—or the acrotretids are paraphyletic with respect to it.> The group displays a broad range of shell structures, some of which incorporate substantial organic or silicified components. References Brachiopod orders Extant Cambrian first appearances {{brachiopod-stub ...
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