期刊
LETHAIA
卷 44, 期 4, 页码 490-495出版社
WILEY
DOI: 10.1111/j.1502-3931.2011.00261.x
关键词
Brachiopods; Cambrian; Chengjiang Lagerstatte; Chileata; colleplax; pedicle
类别
资金
- National Natural Science Foundation of China [40830208, 41072017, 40702005]
- Ministry of Sciences and Technology, China [2006CB806401]
- State Key Laboratory in Northwest University
- China Scholarship Council (CSC)
- Fok Ying Tung Education Foundation [G121016]
- Foundation for the Author of National Excellent Doctoral Dissertation of PR China (FANEDD)
- Fundamental Research Funds for the Central Universities [2010ZY07]
The extraordinary Longtancunella chengjiangensis is one of the rarest and most problematic brachiopods from the Early Cambrian Chengjiang Lagerstatte, where it occurs in unique gregarious clusters with up to ten individuals attached by their stout pedicles to a single hard exoskeleton. Although the general morphology and soft anatomy of Longtancunella is available, its taxonomy and systematic placement within the Brachiopoda remains problematic. New exceptionally preserved specimens show that the pedicle of Longtancunella cannot be considered homologous with the pedicles in crown Rhynchonelliformea or Linguliformea. The pedicle of Longtancunella emerges from a ventral umbonal foramen with a rounded plate that must have been secreted by specialized ventral mantle epithelium. The rounded plate is proposed to be a homologue to the colleplax - a plate covering the umbonal foramen, which is otherwise known from the extinct rhynchonelliform chileates. Longtancunella is proposed to represent a soft-shelled stem rhynchonelliform brachiopod with chileate features, thus demonstrating for the first time that the chileate-like umbonal perforation functions as a pedicle opening. The unusual preservation of the annulated chileate-like holdfast supports the view that it may have been secreted as stacks of chitinous or even mineralized 'attachment pads'. Together with having a spirolophous lophophore and U-shaped gut, Longtancunella displays a unique mixture of linguliform and rhynchonelliform characters that throw new light on an early stage of rhynchonelliform diversification.
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