Fossilized ontogenies: the contribution of placoderm ontogeny to our understanding of the evolution of early gnathostomes |
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Authors: | Zerina Johanson Kate Trinajstic |
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Institution: | 1. Department of Earth Sciences, Natural History Museum, , London, SW75BD UK;2. Western Australian Organic and Isotope Geochemistry Centre, Department of Chemistry, Curtin University, , Perth, Western Australia, 6102 Australia;3. Earth and Planetary Sciences, Western Australian Museum, , Perth, Western Australia, 6000 Australia |
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Abstract: | Placoderms, representing phylogenetically more inclusive jawed vertebrates and successive sister taxa to crown‐group gnathostomes, are critical to our understanding of character evolution within the crown‐group (chondrichthyans + osteichthyans), including developmental characters. Early ontogenetic stages of placoderms are generally poorly known, although some exceptional faunas preserve both embryonic (e.g. from the Gogo Formation, Western Australia) and post‐embryonic individuals (the Miguasha Formation, Canada; Lode Formation, Latvia; Merriganowry Formation, Gogo Formation, Australia). Information provided by these ontogenies is relevant to questions of placoderm taxonomy and phylogeny, but also to broader questions pertinent to vertebrate evolution as a whole, for example, evolution of bone development, evolution of the axial skeleton and evolution of reproduction. |
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Keywords: | ontogeny placoderms embryos axial skeleton dentition reproduction |
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