The origin of multiplacophorans – convergent evolution in Aculiferan molluscs |
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| Authors: | JAKOB VINTHER PETER JELL GEORGE KAMPOURIS RYAN CARNEY RACHEL A RACICOT DEREK E G BRIGGS |
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| Institution: | 1. Department of Geology and Geophysics, Yale University, New Haven, CT 06511, USA;2. e‐mails: rachel.racicot@yale.edu, derek.briggs@yale.edu;3. Current address: Jackson School of Geosciences, University of Texas, Austin, TX 78712, USA;4. e‐mail: jvinther@jsg.utexas.edu;5. Geological Survey of Queensland, PO Box 15216, City East, Queensland, 4002, Australia;6. e‐mail: peter.jell@deedi.qld.gov.au;7. Cincinnati Museum of Natural History, 1301 Western Avenue, Cincinnati, OH 45203‐1130, USA;8. e‐mail: georgekamp@bell.net;9. Deptartment of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA;10. e‐mail: ryan_carney@brown.edu;11. Peabody Museum of Natural History, Yale University, New Haven, CT 06520, USA |
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| Abstract: | Abstract: Multiplacophorans are Palaeozoic (Silurian to Permian) stem group polyplacophorans with 17 shell plates in a particular arrangement of single terminal plates separated by three columns of plates forming five transverse rows. Their distinctive morphology has prompted disparate interpretations of their relationship to polyplacophorans. Some features are strikingly similar to crown group polyplacophorans and even to some living families. Here we describe two Devonian forms, Protobalanus spinicoronatus sp. nov., a hercolepadid from northeast Ohio, USA, and Hannestheronia australis gen. et sp. nov., a strobilepid from South Africa. Using the results from a Bayesian relaxed molecular clock to test competing scenarios of the relationship of multiplacophorans to crown group polyplacophorans, we demonstrate that multiplacophorans are stem group polyplacophorans in which certain characters of the crown group evolved convergently. |
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| Keywords: | Neoloricata Multiplacophora Hercolepadida convergence mollusc Aculifera |
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