title: Development and evolution of dentition pattern and tooth order in the skates and rays (batoidea; chondrichthyes).
abstract: Shark and ray (elasmobranch) dentitions are well known for their multiple generations of teeth, with isolated teeth being common in the fossil record. However, how the diverse dentitions characteristic of elasmobranchs form is still poorly understood. Data on the development and maintenance of the dental patterning in this major vertebrate group will allow comparisons to other morphologically diverse taxa, including the bony fishes, in order to identify shared pattern characters for the vertebrate dentition as a whole. Data is especially lacking from the Batoidea (skates and rays), hence our objective is to compile data on embryonic and adult batoid tooth development contributing to ordering of the dentition, from cleared and stained specimens and micro-CT scans, with 3D rendered models. We selected species (adult and embryonic) spanning phylogenetically significant batoid clades, such that our observations may raise questions about relationships within the batoids, particularly with respect to current molecular-based analyses. We include developmental data from embryos of recent model organisms Leucoraja erinacea and Raja clavata to evaluate the earliest establishment of the dentition. Characters of the batoid dentition investigated include alternate addition of teeth as offset successional tooth rows (versus single separate files), presence of a symphyseal initiator region (symphyseal tooth present, or absent, but with two parasymphyseal teeth) and a restriction to tooth addition along each jaw reducing the number of tooth families, relative to addition of successor teeth within each family. Our ultimate aim is to understand the shared characters of the batoids, and whether or not these dental characters are shared more broadly within elasmobranchs, by comparing these to dentitions in shark outgroups. These developmental morphological analyses will provide a solid basis to better understand dental evolution in these important vertebrate groups as well as the general plesiomorphic vertebrate dental condition.
authors: Department of Earth and Planetary Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, United Kingdom.
authors: Charlie J
authors: CJ
authors: Underwood
authors: Department of Earth Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, United Kingdom.
authors: Zerina
authors: Z
authors: Johanson
authors: Department of Earth Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, United Kingdom.
authors: Monique
authors: M
authors: Welten
authors: Department of Theoretical Biology, University of Vienna, Althanstrasse 14, 1090 Wien, Austria.
authors: Brian
authors: B
authors: Metscher
authors: Department of Animal and Plant Sciences, The University of Sheffield, Sheffield S10 2TN, United Kingdom.
authors: Liam J
authors: LJ
authors: Rasch
authors: Department of Animal and Plant Sciences, The University of Sheffield, Sheffield S10 2TN, United Kingdom.
authors: Gareth J
authors: GJ
authors: Fraser
authors: Department of Earth Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, United Kingdom; King's College London, Dental Institute, Craniofacial Development, London SE1 9RT, United Kingdom.
authors: Moya Meredith
authors: MM
authors: Smith
mesh_terms: D000818:Animals; D005075:Biological Evolution; D003817:Dentition; D005580:Fossils; D008953:Models, Anatomic; D010802:Phylogeny; D012754:Sharks / Q000033:anatomy & histology / Q000196:embryology / Q000254:growth & development; D012860:Skates, Fish / Q000033:anatomy & histology* / Q000196:embryology / Q000254:growth & development; D013045:Species Specificity; D014070:Tooth / Q000033:anatomy & histology* / Q000196:embryology / Q000254:growth & development; D019228:Tooth Crown / Q000033:anatomy & histology / Q000196:embryology / Q000254:growth & development; D014092:Tooth Root / Q000033:anatomy & histology / Q000196:embryology / Q000254:growth & development; D014714:Vertebrates / Q000033:anatomy & histology / Q000145:classification / Q000235:genetics