The Experts below are selected from a list of 45 Experts worldwide ranked by ideXlab platform
Yara Haridy - One of the best experts on this subject based on the ideXlab platform.
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histological analysis of post eruption Tooth wear adaptations and ontogenetic changes in Tooth Implantation in the acrodontan squamate pogona vitticeps
PeerJ, 2018Co-Authors: Yara HaridyAbstract:: Teeth have been a focus of research in both extinct and extant taxa alike; a significant portion of dental literature is concerned with dental patterning and replacement. Most non-mammalian vertebrates continuously replace their dentition but an anomalous group of squamates has forgone this process in only having one Tooth generation; these squamates all have apically implanted teeth, a condition known as acrodonty. Acrodont dentition and various characteristics attributed to it, including a lack of replacement, have often been defined ambiguously. This study explores this type of Implantation through histology in the ontogeny of the acrodont agamid Pogona vitticeps. The non-replacing teeth of this squamate provides an opportunity to study wear adaptations, maintenance of occlusion in a non-mammalian system, and most importantly post-eruption changes in the Tooth bone interface. In this study the post-eruption changes combined with dental wear likely gives the appearance of acrodont Implantation.
Thomas G H Diekwisch - One of the best experts on this subject based on the ideXlab platform.
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varanoid Tooth eruption and Implantation modes in a late cretaceous mosasaur
Frontiers in Physiology, 2016Co-Authors: David A Reed, Giancarlo M Cecchini, Xuanyu Lu, Karan Ganjawalla, Carol S Gonzales, Richard Monahan, Xianghong Luan, Thomas G H DiekwischAbstract:Erupting teeth are some of the oldest witnesses of developmental processes in the vertebrate fossil record and provide an important resource for vertebrate cladistics. Here we have examined a mosasaur jaw fragment from central Texas using ultrathin ground section histology and 3D tomographic imaging to assess features critical for the cladistic placement of mosasaurs among varanoids versus snakes: (i) the orientation of replacement teeth compared to the major Tooth axis, (ii) the occurrence of resorption pits, and (iii) the mode of Tooth Implantation/attachment to the Tooth bearing element. The replacement Tooth studied here developed in an inclined position slightly distal of the deciduous parent Tooth, similar to another varanoid squamate, the Gila monster Heloderma suspectum. Ground sections and tomographs also demonstrated that the replacement Tooth attachment apparatus was entirely intact and that there was no evidence of mechanical deformation. Sections and tomographs further illustrated that the replacement Tooth was located within a bony crypt and the inclination of the crypt matched the inclination of the replacement Tooth. These preparations also revealed the presence of a resorption pit within the boundaries of the deciduous Tooth that surrounded the developing replacement Tooth. This finding suggests that developing mosasaur teeth developed within the walls of resorption pits similar to varanoid Tooth germs and unlike developing snake teeth which are surrounded by fibrous connective tissue integuments. Finally, mosasaurs featured pseudo-thecodont Tooth Implantation with teeth anchored within a socket of mineralized tissue by means of a mineralized periodontal ligament. Together, these data indicate that the moderate inclination of the erupting mosasaur Tooth studied here is neither a result of postmortem displacement nor a character representative of snakes, but rather a shared character between Mosasaurs and other varanoids such as Heloderma. In conjunction with the presence of resorption pits and the evidence for pseudothecodont Tooth Implantation, the Tooth eruption and Implantation characters described in the present study either place mosasaurs among the varanoids or suggest convergent evolution mechanisms between both clades, with mosasaurs evolving somewhat independently from a common varanoid ancestor.
Aaron R H Leblanc - One of the best experts on this subject based on the ideXlab platform.
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current perspectives on Tooth Implantation attachment and replacement in amniota
Frontiers in Physiology, 2018Co-Authors: Thomas J C Bertin, Aaron R H Leblanc, Beatrice Thivichonprince, Michael W Caldwell, Laurent ViriotAbstract:: Teeth and dentitions contain many morphological characters which give them a particularly important weight in comparative anatomy, systematics, physiology and ecology. As teeth are organs that contain the hardest mineralized tissues vertebrates can produce, their fossil remains are abundant and the study of their anatomy in fossil specimens is of major importance in evolutionary biology. Comparative anatomy has long favored studies of dental characters rather than features associated with Tooth attachment and Implantation. Here we review a large part of the historical and modern work on the attachment, Implantation and replacement of teeth in Amniota. We propose synthetic definitions or redefinitions of most commonly used terms, some of which have led to confusion and conflation of terminology. In particular, there has long been much conflation between dental Implantation that strictly concerns the geometrical aspects of the Tooth-bone interface, and the nature of the dental attachment, which mostly concerns the histological features occurring at this interface. A second aim of this work was to evaluate the diversity of Tooth attachment, Implantation and replacement in extant and extinct amniotes in order to derive hypothetical evolutionary trends in these different dental traits over time. Continuous dental replacement prevails within amniotes, replacement being drastically modified only in Mammalia and when dental Implantation is acrodont. By comparison, dental Implantation frequently and rapidly changes at various taxonomic scales and is often homoplastic. This contrasts with the conservatism in the identity of the Tooth attachment tissues (cementum, periodontal ligament, and alveolar bone), which were already present in the earliest known amniotes. Because the study of dental attachment requires invasive histological investigations, this trait is least documented and therefore its evolutionary history is currently poorly understood. Finally, it is essential to go on collecting data from all groups of amniotes in order to better understand and consequently better define dental characters.
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evolutionary implications of Tooth attachment versus Tooth Implantation a case study using dinosaur crocodilian and mammal teeth
Journal of Vertebrate Paleontology, 2017Co-Authors: Aaron R H Leblanc, Kirstin S Brink, Thomas M Cullen, Robert R ReiszAbstract:ABSTRACTTooth attachment and Implantation are two classical descriptors of dental anatomy. Tooth attachment distinguishes between teeth that are either fused to the jaw by bone, or suspended within a socket by a periodontal ligament. Tooth Implantation describes the geometry of this attachment and has been broadly divided into acrodonty, pleurodonty, and thecodonty. Among extant amniotes, only mammals and crocodilians are considered truly thecodont, because they possess a complex attachment system that includes a periodontal ligament and true Tooth sockets. These two amniote groups diverged from a common ancestor over 300 million years ago and are thought to have evolved thecodonty independently. This view has recently come under a great deal of scrutiny with the discovery of complex Tooth attachment systems, including the presence of a ligamentous Tooth attachment in numerous non-mammalian, non-crocodilian amniotes. This has spurred debate and inconsistencies over the conventional usage of Tooth attachme...
Laurent Viriot - One of the best experts on this subject based on the ideXlab platform.
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current perspectives on Tooth Implantation attachment and replacement in amniota
Frontiers in Physiology, 2018Co-Authors: Thomas J C Bertin, Aaron R H Leblanc, Beatrice Thivichonprince, Michael W Caldwell, Laurent ViriotAbstract:: Teeth and dentitions contain many morphological characters which give them a particularly important weight in comparative anatomy, systematics, physiology and ecology. As teeth are organs that contain the hardest mineralized tissues vertebrates can produce, their fossil remains are abundant and the study of their anatomy in fossil specimens is of major importance in evolutionary biology. Comparative anatomy has long favored studies of dental characters rather than features associated with Tooth attachment and Implantation. Here we review a large part of the historical and modern work on the attachment, Implantation and replacement of teeth in Amniota. We propose synthetic definitions or redefinitions of most commonly used terms, some of which have led to confusion and conflation of terminology. In particular, there has long been much conflation between dental Implantation that strictly concerns the geometrical aspects of the Tooth-bone interface, and the nature of the dental attachment, which mostly concerns the histological features occurring at this interface. A second aim of this work was to evaluate the diversity of Tooth attachment, Implantation and replacement in extant and extinct amniotes in order to derive hypothetical evolutionary trends in these different dental traits over time. Continuous dental replacement prevails within amniotes, replacement being drastically modified only in Mammalia and when dental Implantation is acrodont. By comparison, dental Implantation frequently and rapidly changes at various taxonomic scales and is often homoplastic. This contrasts with the conservatism in the identity of the Tooth attachment tissues (cementum, periodontal ligament, and alveolar bone), which were already present in the earliest known amniotes. Because the study of dental attachment requires invasive histological investigations, this trait is least documented and therefore its evolutionary history is currently poorly understood. Finally, it is essential to go on collecting data from all groups of amniotes in order to better understand and consequently better define dental characters.
Robert R Reisz - One of the best experts on this subject based on the ideXlab platform.
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evolutionary implications of Tooth attachment versus Tooth Implantation a case study using dinosaur crocodilian and mammal teeth
Journal of Vertebrate Paleontology, 2017Co-Authors: Aaron R H Leblanc, Kirstin S Brink, Thomas M Cullen, Robert R ReiszAbstract:ABSTRACTTooth attachment and Implantation are two classical descriptors of dental anatomy. Tooth attachment distinguishes between teeth that are either fused to the jaw by bone, or suspended within a socket by a periodontal ligament. Tooth Implantation describes the geometry of this attachment and has been broadly divided into acrodonty, pleurodonty, and thecodonty. Among extant amniotes, only mammals and crocodilians are considered truly thecodont, because they possess a complex attachment system that includes a periodontal ligament and true Tooth sockets. These two amniote groups diverged from a common ancestor over 300 million years ago and are thought to have evolved thecodonty independently. This view has recently come under a great deal of scrutiny with the discovery of complex Tooth attachment systems, including the presence of a ligamentous Tooth attachment in numerous non-mammalian, non-crocodilian amniotes. This has spurred debate and inconsistencies over the conventional usage of Tooth attachme...