3-612: Eodiscidae is a family of agnostid trilobites that lived during the final Lower Cambrian (late Toyonian) and the Middle Cambrian. They are small or very small, and have a thorax of two or three segments. Eodiscidae includes nine genera (see box). The Eodiscids probably descended from the agnostids of family Yukoniidae . Like other agnostids, the body of eodiscids is diminutive, the headshield (or cephalon ) and tailshield (or pygidium ) are of approximately same size, with 2 or 3 thoracic segments in-between, each consisting of
6-410: A horizontal inner portion that abruptly passes into an inclined outer portion (fulcrate). The central raised area of the cephalon (or glabella ) is narrow, usually with parallel sides and rounded front. The furrow between the occipital ring and the more frontal parts of the glabella are a pair of pits low on its sides beneath a large median spine extending from the glabella backwards. The distance between
9-466: The glabella and the border (or preglabellar area) is usually long. This border has dozens of small furrows radiating inward (a so-called scrobiculate border), but this defining feature may be absent in effaced species or destroyed by poor preservation. The axis of the pygidium has four to ten rings. This Agnostida -related article is a stub . You can help Misplaced Pages by expanding it . Agnostida Too Many Requests If you report this error to
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