Malformation and functional morphology as a clue to pedicle size and pedicle morphology of ceratretid brachiopods (Acrotretida; Linguliformea)
2007 (English)In: 51st Palaeontological Association Annual Meeting: Programme with Abstracts, 2007, 96- p.Conference paper (Other scientific)
Evidence for pedicle sizes and pedicle morphologies of fossil linguliform brachiopods is scarce and mainly restricted to exceptionally preserved specimens of fossil Lagerstätten. Recently described specimens of linguloid brachiopods with preserved soft parts have shown that the traditional view of these brachiopods being infaunal and bearing a long pedicle was incorrect, and there existed a wider range of pedicle morphologies and lifestyles. Not all linguloid brachiopods had a burrowing life style, and epibenthic forms with either long thread-like or short and robust pedicles also existed. Despite this variety of pedicles in linguloid brachiopods, virtually nothing is known about pedicle morphology of acrotretid brachiopods, an extremely diverse and common group during the early Palaeozoic. Evidence from a malformed shell of the middle Cambrian Acanthatreta suggests that some acrotretids, i.e., the family Ceratretidae, had a short, pad-like pedicle that permanently attached to a hard substrate. The posterior margin of the malformed shell shows two dents symmetrically arranged adjacent to the pseudointerarea. These dents may have formed because the brachiopod larva had settled in a shallow depression on the seafloor, which imposed lateral growth limitations on the brachiopod shell during the juvenile growth state. As these lateral limitations could not be actively compensated for by the organism, a firm attachment with a short pedicle is assumed. This is in accordance with the funnel shaped external pedicle opening of Acanthatreta, which tapers towards the interior of the shells and probably hosted the main part of the pedicle. This type of opening allows the pedicle to expand rapidly in diameter towards the exterior, thereby enlarging the attachment area and facilitating a firm connection to the substrate.
Place, publisher, year, edition, pages
2007. 96- p.
IdentifiersURN: urn:nbn:se:uu:diva-12593OAI: oai:DiVA.org:uu-12593DiVA: diva2:40362