Portal of Graptolites and Pterobranchs sponsored by "M.M. PLUS M." SZTANDARY |
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Graptolite Net | Graptolites and Graptoliters | Evolution of Graptolites | Crustoidea | Tuboidea | Rhabdopleuroidea | Cephalodiscoidea |
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EVOLUTION AND PHYLOGENETIC CLASSIFICATION OF THE DIPLOGRAPTACEA Abstract of the paper: Mitchell, Ch. E.. 1987. Evolution and phylogenetic classification of the Diplograptacea. - Palaeontology 30, 2, 353-405 |
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The complex astogenetic patterns produced by the specialized, first few thecae (primordial thecae) of graptoloid rhabdosomes were conserved during evolution and provide a reliable guide to 'propinquity of descent' among diplograptids. Using this principle one can redefine their taxonomy, establish phylogenetically meaningful higher taxa, and obtain an improved understanding of diplograptacean phylogeny. The Diplograptacea comprises four major subclades: 1, Orthograptidae: archaic orthograptids (species of the 'Glyptograptus' teretiusculus species group), Orthograptus and Amplexograptus, together with archiretiolitids, lasiograptids, and 'Climacograptus' typicalis - 'G.' lorrainensis groups; 2, Dicranograptidae: dicranograptids plus nemagraptids; 3, Diplograptidae: pseudoclimacograptids and Climacograptus s.s., together with Diplograptus s.s. and offshoots; 4, Monograptidae: 'G' dentatus and descendants including Undulograptus paradoxus, G. euglyphus, 'C.' normalis, and all the Silurian diplograptids including the uniserial monograptines. The first three families dominated Ordovician faunas. Taxa with complex proximal end structures were succeeded during the Llandeilo and Caradoc by taxa with simpler astogenies. Following extinction of the dominant Ordovician taxa, monograptids (sensu lato) underwent explosive evolution in the Llandovery. New generic group taxa: Archiclimacograptus, Arnheimograptus, Diplacanthograptus, Eoglyptograptus, Geniculograptus, Hustedograptus, Oelandograptus, Pseudoamplexograptus, and Urbanekograptus. New family group taxa: Eoglyptograptinae and Orthograptidae. |
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________________________________________________________________________________ Graptolite Net is edited by Piotr Mierzejewski, the Count of Calmont and Countess Maja Anna Korwin-Kossakowska since 2002 |
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