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- Graptolites and Pterobranchs -
WEB PAGES NOT ONLY FOR GRAPTOLITERS
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PRIMITIVE GRAPTOLITHINA
Piotr MIERZEJEWSKI
In: Bjerreskov, M. & Stouge, S. (Eds.) Third International Graptolite Conference Abstracts, 1985, 63.
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Phylogenetic relationships between sessile graptolite orders are still poorly known. There are also many problems
concerning suprageneric taxonomy. The Stolonoidea, commonly regarded as primitive graptolies, are presumably
rhabdopleurids close to Rhabdopleurites Kozlowski. The Dithecoidea, especially those from the Cambrian of Spain, were
colonial scyphopolyps rather than true graptolites. According to Kozlowski (1949, 1962), two main phylogenetic lines in the
graptolite evolution differ distinctly in the mode of budding (a diad or a triad division of the stolon system), and the
budding pattern is regarded as an important diagnostic feature of the graptolite orders. However, Eisenackigraptus
[nomen nudum, = Maenilligraptus Mierzejewski, 1985] reveals budding in diads as well as in triads. Moreover, one can
observe a so far unknown type of the stolon trifurcation in this form. Presumably Eisenackigraptus represents group of
graptolites linking two lines in the graptolite evolution. Another aberrant form, Urbanekicrusta Mierzejewski combines
some features of three orders, i.e. the Crustoidea, Tuboidea and Camaroidea. It represents an unknown line in the
crustoid evolution.
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__________________________________________________________________________________
GRAPTOLITE NET
is edited and periodically updated by
Dr Piotr Mierzejewski, Count of Calmont
since 2002
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