Developmental Basis of Toothlessness in Turtles: Insight Into Convergent Evolution of Vertebrate Morphology

Tokita, Masayuki; Chaeychomsri, Win; Siruntawineti, Jindawan

doi:10.1111/j.1558-5646.2012.01752.x

Cited by 44 publications

(46 citation statements)

References 71 publications

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“…The conservation of the tooth unit is extremely stable with the exception of those vertebrates, like the birds (Class Aves), turtles (order Testudines/Chelonii) and some mammals (including the anteaters; suborder Vermilingua) that have lost their tooth building capability and are for the most part, toothless. These toothless clades have all secondarily lost their teeth with fossil evidence showing toothed forms of most groups [6,15]. Interestingly, there are many vertebrates that do develop an initial and complete set of teeth that are lost and never replaced.…”

Section: Tooth Replacement: An Ancient Systemmentioning

confidence: 99%

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Evolution and developmental diversity of tooth regeneration

Tucker

Fraser

2014

Seminars in Cell & Developmental Biology

123

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a b s t r a c tThis review considers the diversity observed during both the development and evolution of tooth replacement throughout the vertebrates in a phylogenetic framework from basal extant chondrichthyan fish and more derived teleost fish to mammals. We illustrate the conservation of the tooth regeneration process among vertebrate clades, where tooth regeneration refers to multiple tooth successors formed de novo for each tooth position in the jaws from a common set of retained dental progenitor cells. We discuss the conserved genetic mechanisms that might be modified to promote morphological diversity in replacement dentitions. We review current research and recent progress in this field during the last decade that have promoted our understanding of tooth diversity in an evolutionary developmental context, and show how tooth replacement and dental regeneration have impacted the evolution of the tooth-jaw module in vertebrates.

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Section: Tooth Replacement: An Ancient Systemmentioning

confidence: 99%

“…Reptiles can be divided into the Lepidosauria (Squamata and Rhynchocephalia), Crocodilia and the Chelonia (Testudines), with all extant Chelonia being edentate [6,15]. The Lepidosauria and Crocodilia are all toothed and are generally polyphyodont.…”

Section: Reptilesmentioning

confidence: 99%

Evolution and developmental diversity of tooth regeneration

Tucker

Fraser

2014

Seminars in Cell & Developmental Biology

123

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“…Dorsoventrally broadened distribution of osteogenic mesenchymal precursor cells in the temporal region of the head owing to the regulatory alteration of these osteogenic genes may allow this reptilian lineage to reacquire the anapsid skull. Although the precise mechanism underlying regulatory change of Msx2 expression in the head of turtle embryos has not been identified, recent findings that early stage arrest of Msx2 expression in neural crest-derived odontoblasts may account for the absence of teeth in turtles (Tokita et al, 2012) supports the hypothesis that this transcription factor may play a pivotal role in the development of their unique cranial morphology.…”

Section: Discussionmentioning

confidence: 97%

“…To identify the expression domain of Msx1 in crocodile tissues, chicken Msx1 antisense riboprobe was hybridized. Generally, hetero-specific RNA probes easily hybridize among reptilian lineages (Harris et al, 2006, Tokita et al, 2012). In this study, we only analyzed reptilian embryos at the ontogenetic stages where early cranial osteogenesis occurs.…”

Section: Methodsmentioning

confidence: 99%

Skeletal gene expression in the temporal region of the reptilian embryos: implications for the evolution of reptilian skull morphology

2013

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Reptiles have achieved highly diverse morphological and physiological traits that allow them to exploit various ecological niches and resources. Morphology of the temporal region of the reptilian skull is highly diverse and historically it has been treated as an important character for classifying reptiles and has helped us understand the ecology and physiology of each species. However, the developmental mechanism that generates diversity of reptilian skull morphology is poorly understood. We reveal a potential developmental basis that generates morphological diversity in the temporal region of the reptilian skull by performing a comparative analysis of gene expression in the embryos of reptile species with different skull morphology. By investigating genes known to regulate early osteoblast development, we find dorsoventrally broadened unique expression of the early osteoblast marker, Runx2, in the temporal region of the head of turtle embryos that do not form temporal fenestrae. We also observe that Msx2 is also uniquely expressed in the mesenchymal cells distributed at the temporal region of the head of turtle embryos. Furthermore, through comparison of gene expression pattern in the embryos of turtle, crocodile, and snake species, we find a possible correlation between the spatial patterns of Runx2 and Msx2 expression in cranial mesenchymal cells and skull morphology of each reptilian lineage. Regulatory modifications of Runx2 and Msx2 expression in osteogenic mesenchymal precursor cells are likely involved in generating morphological diversity in the temporal region of the reptilian skull.Electronic supplementary materialThe online version of this article (doi:10.1186/2193-1801-2-336) contains supplementary material, which is available to authorized users.

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“…The evolutionary loss of teeth occurred in turtles [8] and birds [9] approximately 100 million years ago, to be replaced by horny beaks as an evolutionary adaptation to changed diets. The extraordinary "lawn-mower" dental battery of Nigersaurus (Figure 1), adapted to an herbivorous diet is trumped for deviant dentitions by the bizarre spiral tooth whorl in the fossil Helicoprion [10] (Figure 2).…”

Section: Comparative Odontologymentioning

confidence: 99%

The Divination of Dentitions in Evolution

Sperber¹

2013

J Phylogen Evolution Biol

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Teeth are quintessential elements of evolutionary evidence imposed by ecological niches and determined by dietary demands. By virtue of their postmortem durability, teeth are often the only remaining remnants of long extinct species to provide presumption of their previous paleontological existence. That teeth are intimately associated with dietary intake provides unambiguous evidence of ancient ambient environments and extinct cultural practices. Spectroscopic analysis of enamel and attritional dental wear reveal archaic food composition. Genetic inheritance patterns contained in varying dental configurations reveal permutations of evolutionary trends. Analysis of the preserved mitochondrial DNA of archaic dental pulp tissue of long-deceased antecedents and historical figures of mankind is the current research focus of phylogenetics and evolutionary biology.

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Developmental Basis of Toothlessness in Turtles: Insight Into Convergent Evolution of Vertebrate Morphology

Abstract: The tooth is a major component of the vertebrate feeding apparatus and plays a crucial role in species survival, thus subjecting tooth

Cited by 44 publications

References 71 publications

Evolution and developmental diversity of tooth regeneration

Evolution and developmental diversity of tooth regeneration

Skeletal gene expression in the temporal region of the reptilian embryos: implications for the evolution of reptilian skull morphology

The Divination of Dentitions in Evolution

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