A Review of Tooth Implantation Among Rhynchocephalians (Lepidosauria)

Jenkins, Kelsey M.; Jones, Marc E. H.; Zikmund, Tomáš; Boyde, A.; Daza, Juan D.

doi:10.1670/16-146

Cited by 30 publications

(32 citation statements)

References 59 publications

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“…The dentition of the only current representative of Rhynchocephalia, Sphenodon punctatus , displays an acrodont implantation ( Kieser et al, 2009 ; Jenkins et al, 2017 ). Most members of Squamata have teeth with pleurodont implantation, apart from Agamidae and Chamaeleonidae that present, respectively, mixed acrodont and pleurodont tooth implantations and exclusively acrodont implantation in others ( Zaher and Rieppel, 1999 ).…”

Section: Diversity Of Tooth Attachment Implantation and Replacement mentioning

confidence: 99%

“…Indeed, part of the anterior dentition of hatchlings is replaced by one larger tooth, that will in its turn be replaced ( Harrison, 1901 ; Rieppel, 1992 ; Berkovitz and Shellis, 2017 ). Teeth implanted by acrodonty thus are systematically monophyodont in squamates, and the replacement is very limited in Sphenodon ( Harrison, 1901 ; Rieppel, 1992 ; Jones et al, 2012 ; Jenkins et al, 2017 ). Cooper et al (1970) also suggested that tooth replacement of pleurodont teeth in Agamidae was slow.…”

Section: Diversity Of Tooth Attachment Implantation and Replacement mentioning

confidence: 99%

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Current Perspectives on Tooth Implantation, Attachment, and Replacement in Amniota

et al. 2018

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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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Section: Diversity Of Tooth Attachment Implantation and Replacement mentioning

confidence: 99%

Section: Diversity Of Tooth Attachment Implantation and Replacement mentioning

confidence: 99%

Current Perspectives on Tooth Implantation, Attachment, and Replacement in Amniota

et al. 2018

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“…Once again, examination of a fossil member of Rhynchocephalia highlights the diversity of this group and demonstrates that Sphenodon is not necessarily representative of its Mesozoic relatives [ 2 , 12 ]. The greater enamel thickness in Eilenodon , compared with the smaller Sphenodon (and smaller still, Sphenocondor ), may be related to scaling but examination of additional Rhynchocephalia, such as Clevosaurus from the Triassic of the UK [ 18 ], are required to test this hypothesis. Nevertheless, the tooth enamel thickness of Eilenodon appears to be greater than that of crocodylians [ 31 , 32 ] and some dinosaurs [ 33 ].…”

Section: Discussionmentioning

confidence: 99%

Neutron scanning reveals unexpected complexity in the enamel thickness of an herbivorous Jurassic reptile

Jones

Lucas

Tucker

et al. 2018

J. R. Soc. Interface.

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Eilenodontines are one of the oldest radiation of herbivorous lepidosaurs (snakes, lizards and tuatara) characterized by batteries of wide teeth with thick enamel that bear mammal-like wear facets. Unlike most reptiles, eilenodontines have limited tooth replacement, making dental longevity particularly important to them. We use both X-ray and neutron computed tomography to examine a fossil tooth from the eilenodontine Eilenodon (Late Jurassic, USA). Of the two approaches, neutron tomography was more successful and facilitated measurements of enamel thickness and distribution. We find the enamel thickness to be regionally variable, thin near the cusp tip (0.10 mm) but thicker around the base (0.15–0.30 mm) and notably greater than that of other rhynchocephalians such as the extant Sphenodon (0.08–0.14 mm). The thick enamel in Eilenodon would permit greater loading, extend tooth lifespan and facilitate the establishment of wear facets that have sharp edges for orally processing plant material such as horsetails (Equisetum). The shape of the enamel dentine junction indicates that tooth development in Eilenodon and Sphenodon involved similar folding of the epithelium but different ameloblast activity.

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“…Among lepidosaurian reptiles, this suppression of replacement is limited to Sphenodontidae (Rhynchocephalia) , Chamaeleonidae , and Agamidae , with the latter two being grouped within the clade Acrodonta (Squamata) ( Pyron, Burbrink & Wiens, 2013 ). This squamate group is aptly named for the acrodont style implantation of the dentition, and all acrodontians have apically implanted teeth making up the majority of their dentulous surface ( Edmund, 1960 ; Peyer, 1968 ; Zaher & Rippel, 1999 ; Cooper, Poole & Lawson, 1970 ; Jenkins et al, 2017 ). This is in contrast to the condition found in most squamates and other reptiles (e.g., Zaher & Rippel, 1999 ; Delgado, Davit-Beal & Sire, 2003 ; LeBlanc & Reisz, 2015 ) in which the tooth is implanted to the lingual surface of the jaw bone, a condition known as pleurodonty that is exemplified in taxa like Iguana iguana ( Throckmorton, 1976 ; Montanucci, 2008 ; Kline & Cullum, 2017 ).…”

Section: Introductionmentioning

confidence: 99%

“…The classic categories of acrodonty, pleurodonty, and thecodonty have been used as descriptors, as well as phylogenetic characters ( Zaher & Rippel, 1999 ), and continue in even the latest literature ( Jenkins et al, 2017 ) but have been called into question by Estes & Charles (1988) who suggested these categories are artificial and are not likely representative of natural groupings. To ground truth the use of acrodontians as acrodont representatives the natural question becomes: are the acrodont teeth of acrodontians really acrodont?…”

Section: Introductionmentioning

confidence: 99%

Histological analysis of post-eruption tooth wear adaptations, and ontogenetic changes in tooth implantation in the acrodontan squamate Pogona vitticeps

Haridy

2018

PeerJ

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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.

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A Review of Tooth Implantation Among Rhynchocephalians (Lepidosauria)

Cited by 30 publications

References 59 publications

Current Perspectives on Tooth Implantation, Attachment, and Replacement in Amniota

Current Perspectives on Tooth Implantation, Attachment, and Replacement in Amniota

Neutron scanning reveals unexpected complexity in the enamel thickness of an herbivorous Jurassic reptile

Histological analysis of post-eruption tooth wear adaptations, and ontogenetic changes in tooth implantation in the acrodontan squamate Pogona vitticeps

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