| Acaenoplax Temporal range:
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|---|---|
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | incertae sedis |
| Family: | †Heloplacidae |
| Genus: | †Acaenoplax |
| Species: | †A. hayae
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| Binomial name | |
| †Acaenoplax hayae Sutton et al, 2001
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Acaenoplax is an extinct worm-shaped mollusc known from the Coalbrookdale Formation of Herefordshire, England. It lived in the Silurian period. It was a couple of centimetres long and half a centimetre wide, and comprises serially repeated units with seven or eight shells, and rings of 'spines'.[1][2]
Some of its characters are reminiscent of the polychaete worms, and the character combinations do not place it obviously in the stem of any modern mollusc group,[3] but although it was originally interpreted as a polychaete,[1] this position is untenable for a number of reasons.[4]
- ^ a b Sutton, M. D.; Briggs, D. E. G.; Siveter, D. J.; Siveter, D. J. (Mar 2001). "An exceptionally preserved vermiform mollusc from the Silurian of England". Nature. 410 (6827): 461–463. doi:10.1038/35068549. ISSN 0028-0836. PMID 11260711.
- ^ Sutton, M. D.; Briggs, D. E. G.; Siveter, D. J.; Siveter, D. J. (2004). "Computer reconstruction and analysis of the vermiform mollusc Acaenoplax hayae from the Herefordshire Lagerstatte (Silurian, England), and implications for molluscan phylogeny". Palaeontology. 47 (2): 293–318. doi:10.1111/j.0031-0239.2004.00374.x.
- ^ Steiner, G.; Salvini-Plawen, L. (Dec 2001). "Acaenoplax—polychaete or mollusc?". Nature. 414 (6864): 601–602, discussion 602. doi:10.1038/414601a. ISSN 0028-0836. PMID 11740549.
- ^ Sutton, M.; Briggs, D. E. G.; Siveter, D. J.; Siveter, D. J. (2001). "Acaenoplax—polychaete or mollusc?". Nature. 414 (6864): 602. doi:10.1038/414602a.