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Laboratoire de Paléontologie, et Paléogéographie du Paléozoïque, UMR 8014 du CNRS, Université des Sciences et Technologies de Lille, Bâtiment SN5 Cité Scientifique, F-59655 Villeneuve dAscq, France
Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, 210008 Nanjing, China
British Geological Survey, Kingsley Dunham Centre, Keyworth, Nottingham NG12 5GG, United Kingdom
Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, Makarova Embankment 2, Saint Petersburg 199034, Russia
Unidad de Palaeopalinología, IANIGLA, CRICYT, C.C. 131, 5500 Mendoza, Argentina
Correspondence: 1 corresponding author, e-mail: thomas.servais{at}univ-lille1.fr
Veryhachium Deunff 1954, originally described from the Ordovician of western France, is one of the most frequently recorded acritarch genera. Over 250 species and subspecies, from the Cambrian to the Neogene, have been attributed to the genus. This genus has a simple morphology; it displays a triangular, rectangular, or polygonal central vesicle, with a few, simple processes drawn out from the angles of the vesicle in a single plane, and sometimes with supplementary or auxillary processes arising from the vesicle body. Veryhachium has been emended and revised numerous times. The number of valid species is excessive: most are probably synonyms. To facilitate effective classification, only a few morphological categories should be retained. For the Lower Paleozoic, the use of two informal groups is proposed. These are the Veryhachium trispinosum group for triangular specimens, and the Veryhachium lairdii group for rectangular forms. Although generally abundant and widespread throughout the Phanerozoic, Veryhachium is of limited biostratigraphic, paleoecologic, or paleogeographic value. However, its First Appearance Datum (FAD) is of great importance for Ordovician stratigraphy; the first Veryhachium morphotypes appear in the Tremadocian Stage, making the genus an important biostratigraphic marker.
Key Words: Ordovician Tremadocian acritarchs organic-walled microphytoplankton taxonomy biostratigraphy
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