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Proximal structure and development in the Ordovician graptolite Parisograptus Chen and Zhang, 1996
Author(s) -
Maletz Jörg,
Zhang Yuandong
Publication year - 2003
Publication title -
palaeontology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.69
H-Index - 63
eISSN - 1475-4983
pISSN - 0031-0239
DOI - 10.1111/1475-4983.00299
Subject(s) - paleontology , ordovician , dorsum , development (topology) , string (physics) , zhàng , geology , biology , anatomy , physics , geography , mathematics , china , theoretical physics , archaeology , mathematical analysis
The proximal development of Parisograptus Chen and Zhang is described from three–dimensionally preserved specimens. The unique development features an origin of proximal thecae like a string of pearls vertically upon each other on the reverse side of the rhabdosome with the dorsal sides of the initial stipes placed side by side. The development differs strongly from that found in the superficially similar Arienigraptus in which the first thecal pairs grow downwards side by side, even though the rhabdosome shapes are quite similar. It represents a first step towards the development of a completely biserial rhabdosome and eventually leads to the biserial, monopleural glossograptids.