Abstract
The fossil echinoderm Palaeocucumaria, from the early Devonian Hunsruck Slate of southwestern Germany, has been studied using both traditional techniques and X-ray microtomography, and its anatomy clarified. Phylogenetic analysis shows that it is a stem-group holothurian with a combination of characters that help understand how the modern (crown-group) holothurian body plan developed. Echinoids and holothurians have evolved along different paths, by differential growth of the larval- and rudment-derived body regions. Palaeocucumaria shows that late stem-group holothurians had a water vascular organization with a single external madreporite and calcified stone canal leading to the aboral end of the peripharyngeal coelom, and five primary radial water vessels that gave rise to tentacle-like tube-feet. This fossil data, in combination with a molecular phylogeny based on 18 s-like rRNA gene sequence data, is used to order evolutionary steps in the making of the crown-group holothurian body plan. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 670–681.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
