海笔 (棘皮动物)

海笔纲; 化石时期：苗岭世 PreЄ Є O S D C P T J K Pg N
	产自捷克的Trochocystites bohemicus化石，长15毫米
科学分类
界：	动物界 Animalia
门：	棘皮动物门 Echinodermata
亚门：	†海扁果亚门 Homalozoa
纲：	†海笔纲 Cincta; Jaekel, 1918
科
	†Trochocystitidae; †Gyrocystidae; †Sucocystidae;
异名
	同柱纲 Homostelea Gill & Caster, 1960;

海笔（Cinctans）是一类已灭绝的棘皮动物，化石只发现于中寒武纪^[2]^[3]，分布于欧洲及北非摩洛哥。^[4]海笔的分类地位尚有争议，一般认为属于棘皮动物干群。^[2]^[3]其身体缺乏对称性，外观类似球拍，可分为两部分，分别为由不规则骨板构成的勺状萼（theca），以及后方延伸出的茎尾（stele）。^[5]无柄和腕，口与肛门位于萼的同一侧。它们的生活方式可能类似现代的被囊动物，以鳃口滤食海水中的浮游生物和有机物颗粒为生。^[2]

参考文献

^ Lefebvre, Bertrand; Derstler, Kraig; Sumrall, Colin D. A reinterpretation of the solutan Plasiacystis mobilis (Echinodermata) from the Middle Ordovician of Bohemia. Zoosymposia. 2012, 7: 287–306. doi:10.11646/zoosymposia.7.1.27.
^ ^2.0 ^2.1 ^2.2 Rahman, Imran A.; Zamora, Samuel. The oldest cinctan carpoid (stem-group Echinodermata), and the evolution of the water vascular system. Zoological Journal of the Linnean Society. 2009, 157 (2): 420–432. doi:10.1111/j.1096-3642.2008.00517.x .
^ ^3.0 ^3.1 Rahman, Imran A.; Zamora, Samuel; Falkingham, Peter L.; Phillips, Jeremy C. Cambrian cinctan echinoderms shed light on feeding in the ancestral deuterostome. Proceedings of the Royal Society B. 2015, 282 (1818). PMC 4650160 . PMID 26511049. doi:10.1098/rspb.2015.1964 .
^ Zamora, Samuel; Lefebvre, Bertrand; Javier Álvaro, J.; Clausen, Sébastien; Elicki, Olaf; Fatka, Oldrich; Jell, Peter; Kouchinsky, Artem; Lin, Jih-Pai; Nardin, Elise; Parsley, Ronald; Rozhnov, Sergei; Sprinkle, James; Sumrall, Colin D.; Vizcaïno, Daniel; Smith, Andrew B. Cambrian echinoderm diversity and palaeobiogeography. Geological Society, London, Memoirs. 2013, 38 (1): 157–171. S2CID 130481550. doi:10.1144/M38.13.
^ Jefferies, R. P. S. The solute Dendrocystites scoticus from the Upper Ordovician of Scotland and the ancestry of chordates and echinoderms. Palaeontology. 1990, 33 (3): 631–679.

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[Lefebvre2012-1] Lefebvre, Bertrand; Derstler, Kraig; Sumrall, Colin D. A reinterpretation of the solutan Plasiacystis mobilis (Echinodermata) from the Middle Ordovician of Bohemia. Zoosymposia. 2012, 7: 287–306. doi:10.11646/zoosymposia.7.1.27.

[Rahman2009-2] 2.0 ^2.1 ^2.2 Rahman, Imran A.; Zamora, Samuel. The oldest cinctan carpoid (stem-group Echinodermata), and the evolution of the water vascular system. Zoological Journal of the Linnean Society. 2009, 157 (2): 420–432. doi:10.1111/j.1096-3642.2008.00517.x .

[Rahman2015-3] 3.0 ^3.1 Rahman, Imran A.; Zamora, Samuel; Falkingham, Peter L.; Phillips, Jeremy C. Cambrian cinctan echinoderms shed light on feeding in the ancestral deuterostome. Proceedings of the Royal Society B. 2015, 282 (1818). PMC 4650160 . PMID 26511049. doi:10.1098/rspb.2015.1964 .

[Zamora2013B-4] Zamora, Samuel; Lefebvre, Bertrand; Javier Álvaro, J.; Clausen, Sébastien; Elicki, Olaf; Fatka, Oldrich; Jell, Peter; Kouchinsky, Artem; Lin, Jih-Pai; Nardin, Elise; Parsley, Ronald; Rozhnov, Sergei; Sprinkle, James; Sumrall, Colin D.; Vizcaïno, Daniel; Smith, Andrew B. Cambrian echinoderm diversity and palaeobiogeography. Geological Society, London, Memoirs. 2013, 38 (1): 157–171. S2CID 130481550. doi:10.1144/M38.13.

[Jefferies1990-5] Jefferies, R. P. S. The solute Dendrocystites scoticus from the Upper Ordovician of Scotland and the ancestry of chordates and echinoderms. Palaeontology. 1990, 33 (3): 631–679.

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