J. Yang
Introvert and pharynx of Mafangscolex, a Cambrian palaeoscolecid
Yang, J.; Smith, M.R.; Zhang, X.-G.; Yang, X.-Y.
Abstract
Palaeoscolecid worms are widespread in the Palaeozoic period, and are of key importance to understanding the emergence of moulting animals (superphylum Ecdysozoa). However, palaeoscolecids lack a diagnostic set of morphological characters, and as such are unlikely to form a natural (monophyletic) group. Consequently, detailed anatomical study of individual taxa is necessary in order to evaluate the phylogenetic significance of palaeoscolecids. New specimens of Mafangscolex from the Cambrian Stage 3 Xiaoshiba Lagerstätte in Kunming, China, provide the first detailed account of a proboscis in Palaeoscoelcida sensu stricto, a core group of palaeoscolecids characterized by having a tessellating scleritome of phosphatic plates and platelets. The eversible mouthparts of Mafangscolex comprise an armoured, hexaradially symmetrical introvert, a ring of coronal spines and quincuncially arranged pharyngeal armature, with a range of tooth morphologies. Taken together, this configuration strikingly resembles the proboscis arrangement inferred for the ancestral ecdysozoan. The six-fold symmetry represents an important difference from the pentaradial priapulan proboscis. The retention of key aspects of the ancestral ecdysozoan body plan suggests that palaeoscolecids represent a useful window on the earliest stages of ecdysozoan evolution.
Citation
Yang, J., Smith, M., Zhang, X., & Yang, X. (2020). Introvert and pharynx of Mafangscolex, a Cambrian palaeoscolecid. Geological Magazine, 157(12), 2044-2050. https://doi.org/10.1017/s0016756820000308
Journal Article Type | Article |
---|---|
Acceptance Date | Mar 24, 2020 |
Online Publication Date | Apr 21, 2020 |
Publication Date | 2020-12 |
Deposit Date | Apr 21, 2020 |
Publicly Available Date | Oct 21, 2020 |
Journal | Geological Magazine |
Print ISSN | 0016-7568 |
Electronic ISSN | 1469-5081 |
Publisher | Cambridge University Press |
Peer Reviewed | Peer Reviewed |
Volume | 157 |
Issue | 12 |
Pages | 2044-2050 |
DOI | https://doi.org/10.1017/s0016756820000308 |
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Copyright Statement
This article has been published in a revised form in Geological magazine http://doi.org/10.1017/S0016756820000308. This version is published under a Creative Commons CC-BY-NC-ND. No commercial re-distribution or re-use allowed. Derivative works cannot be distributed. © Cambridge University Press 2020.
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