Class Trilobita Family Agnostidae | Order Agnostida Rank Genus | |
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Similar Condylopyge, Agnostidae, Sphaeragnostus, Peronopsis, Agnostina | ||
Phalagnostus is a genus of small trilobites, in the order Agnostida. It lived during the Middle Cambrian, in what are now Canada (Newfoundland and Northwest Territories), China, the Czech Republic, Denmark, England, France, the Russian Federation (Bennett Island, Yakutia), Wales, Sweden, and possibly the United States (Vermont). The headshield (or cephalon) is almost entirely effaced and wider than the tailshield (or pygidium). The pygidium is also very effaced, but the ovate pygidial axis (or rhachis) is well defined and a border furrow is also present.
Contents
Taxonomy
Phalagnostus nudus, the type species, was originally described as a species of Battus by Beyrich in 1845, but that name had already been used for a butterfly, and the trilobite genus was also deemed polyphyletic.
Due to the high level of effacement, it is difficult to establish the relationship of Phalagnostus to other Agnostoidea. The Treatise lists Phalagnostus as Family unknown.
Species previously assigned to Phalagnostus
Distribution
Description
This agnostoid is strongly effaced. The cephalon lacks a border furrow. The glabella and small basal lobes are weakly defined. The rhachis is circular to ovate, clearly defined by deep axial furrows. An elongate axial node may be discerned. The pygidium has a narrow border defined by a furrow.