Project 3468: R. P. Dearden, C. Stockey, M. D. Brazeau. 2019. The pharynx of the stem-chondrichthyan Ptomacanthus and the early evolution of the gnathostome gill skeleton. Nature Communications. 10 (1):article number 20150.
Specimen: † Ptomacanthus anglicus (NHM:P.24919a)
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Abstract

The gill apparatus of gnathostomes (jawed vertebrates) is fundamental to feeding and ventilation and a focal point of classic hypotheses on the origin of jaws and paired appendages. The gill skeletons of chondrichthyans (sharks, batoids, chimaeras) have often been assumed to reflect ancestral states. However, only a handful of early chondrichthyan gill skeletons are known and palaeontological work is increasingly challenging other pre-supposed shark-like aspects of ancestral gnathostomes. Here we use computed tomography scanning to image the three-dimensionally preserved branchial apparatus in Ptomacanthus, a 415 million year old stem-chondrichthyan. Ptomacanthus had an osteichthyan-like compact pharynx with a bony operculum helping constrain the origin of an elongate elasmobranch-like pharynx to the chondrichthyan stem-group, rather than it representing an ancestral condition of the crown-group. A mixture of chondrichthyan-like and plesiomorphic pharyngeal patterning in Ptomacanthus challenges the idea that the ancestral gnathostome pharynx conformed to a morphologically complete ancestral type.


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Article DOI: 10.1038/s41467-019-10032-3

Project DOI: 10.7934/P3468, http://dx.doi.org/10.7934/P3468
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MorphoBank Project 3468
  • Creation Date:
    03 May 2019
  • Publication Date:
    30 May 2019
  • Project views: 331


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    Tanya Berardini
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    Last logged in 05/30/19
    111
    Martin Brazeau
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    Richard Dearden
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    Christopher Stockey
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