Tooth histology in the cretaceous ichthyosaur Platypterygius australis, and its significance for the conservation and divergence of mineralized tooth tissues in amniotes

摘要: Ichthyosaurs are an extinct group of secondarily aquatic reptiles that show ligamentous tooth attachment to the jaw in some derived forms. Here, we provide a modern description histology ichthyosaurs, using Platypterygius australis, large ichthyosaur from Cretaceous Australia. Our study supports evolutionary conservation principal mineralized tissue types amniotes with attachment: enamel, dentine, cellular, and acellular cementum. This is first time latter has been located ichthyosaurs. Vascularized cementum (osteocementum) reduced or absent which teeth ankylosed bone, such as basal raises questions regarding function this potential developmental selective conditions leading its convergent evolution. J. Morphol., 2011. © 2010 Wiley-Liss, Inc.