頭胸足類

Prosomapoda; 化石时期：Ordovician至Recent PreЄ Є O S D C P T J K Pg N
	Cryptocellus goodnighti，一种节腹目蜘蛛
科学分类
界：	动物界 Animalia
门：	节肢动物门 Arthropoda
演化支：	蛛形类 Arachnomorpha
亚门：	螯肢亚门 Chelicerata
演化支：	真螯肢类 Euchelicerata
演化支：	頭胸足類 Prosomapoda; Lamsdell, 2013
分类群
	†?Borchgrevinkium; †Synziphosurina; Planaterga; 剑尾目;

頭胸足類（学名：Prosomapoda）是螯肢亞門的一个演化支，其成员包括：剑尾目、平背板类（Planaterga，此类群又涵盖了Bunodidae、Pseudoniscidae、渊盾鲎目（Chasmataspidida）、广翅鲎目和蛛形纲）以及数个Synziphosurina亚目的物种^[1]。该演化支的主要界定特征在于：在成体期，其前体附肢的第二至第五对（即附肢II-V）缺乏外肢^[1]。相比之下，在非頭胸足類的螯肢亞門动物，如奥法虫属（Offacolus）和双足秘虫属（Dibasterium）中，其附肢II-V的外肢则发育得相当完善^[2]^[3]。

参考文献

^ ^1.0 ^1.1 Lamsdell, James C. Revised systematics of Palaeozoic 'horseshoe crabs' and the myth of monophyletic Xiphosura. Zoological Journal of the Linnean Society. 2012-12-18, 167 (1): 1–27. ISSN 0024-4082. doi:10.1111/j.1096-3642.2012.00874.x  （英语）.
^ Sutton, Mark D.; Briggs, Derek E. G.; Siveter, David J.; Siveter, Derek J.; Orr, Patrick J. The arthropod Offacolus kingi (Chelicerata) from the Silurian of Herefordshire, England: computer based morphological reconstructions and phylogenetic affinities. Proceedings of the Royal Society of London. Series B: Biological Sciences. 2002-06-22, 269 (1497): 1195–1203. ISSN 0962-8452. PMC 1691018 . PMID 12065034. doi:10.1098/rspb.2002.1986 （英语）.
^ Briggs, Derek E. G.; Siveter, Derek J.; Siveter, David J.; Sutton, Mark D.; Garwood, Russell J.; Legg, David. Silurian horseshoe crab illuminates the evolution of arthropod limbs. Proceedings of the National Academy of Sciences. 2012-09-25, 109 (39): 15702–15705. Bibcode:2012PNAS..10915702B. ISSN 0027-8424. PMC 3465403 . PMID 22967511. doi:10.1073/pnas.1205875109  （英语）.

[:0-1] 1.0 ^1.1 Lamsdell, James C. Revised systematics of Palaeozoic 'horseshoe crabs' and the myth of monophyletic Xiphosura. Zoological Journal of the Linnean Society. 2012-12-18, 167 (1): 1–27. ISSN 0024-4082. doi:10.1111/j.1096-3642.2012.00874.x  （英语）.

[2] Sutton, Mark D.; Briggs, Derek E. G.; Siveter, David J.; Siveter, Derek J.; Orr, Patrick J. The arthropod Offacolus kingi (Chelicerata) from the Silurian of Herefordshire, England: computer based morphological reconstructions and phylogenetic affinities. Proceedings of the Royal Society of London. Series B: Biological Sciences. 2002-06-22, 269 (1497): 1195–1203. ISSN 0962-8452. PMC 1691018 . PMID 12065034. doi:10.1098/rspb.2002.1986 （英语）.

[3] Briggs, Derek E. G.; Siveter, Derek J.; Siveter, David J.; Sutton, Mark D.; Garwood, Russell J.; Legg, David. Silurian horseshoe crab illuminates the evolution of arthropod limbs. Proceedings of the National Academy of Sciences. 2012-09-25, 109 (39): 15702–15705. Bibcode:2012PNAS..10915702B. ISSN 0027-8424. PMC 3465403 . PMID 22967511. doi:10.1073/pnas.1205875109  （英语）.

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