The palatal dentition of tetrapods and its functional significance

Matsumoto, Ryoko; Evans, SE

doi:10.1111/joa.12534

Cited by 28 publications

(35 citation statements)

References 138 publications

(217 reference statements)

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“…The ectopterygoid bears no teeth. This was to be expected as ectopterygoidal teeth are virtually absent among archosauromorphs, but do occur in non-saurian diapsids 68 .…”

Section: Quadratojugalmentioning

confidence: 81%

Cranial morphology of the tanystropheid Macrocnemus bassanii unveiled using synchrotron microtomography

Miedema

Spiekman

Fernández

et al. 2020

Sci Rep

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the genus Macrocnemus is a member of the Tanystropheidae, a clade of non-archosauriform archosauromorphs well known for their very characteristic, elongated cervical vertebrae. Articulated specimens are known from the Middle Triassic of Alpine Europe and China. Although multiple articulated specimens are known, description of the cranial morphology has proven challenging due to the crushed preservation of the specimens. Here we use synchrotron micro computed tomography to analyse the cranial morphology of a specimen of the type species Macrocnemus bassanii from the Besano Formation of Monte San Giorgio, Ticino, Switzerland. The skull is virtually complete and we identify and describe the braincase and palatal elements as well the atlas-axis complex for the first time. Moreover, we add to the knowledge of the morphology of the skull roof, rostrum and hemimandible, and reconstruct the cranium of M. bassanii in 3D using the rendered models of the elements. The circumorbital bones were found to be similar in morphology to those of the archosauromorphs Prolacerta broomi and Protorosaurus speneri. In addition, we confirm the palatine, vomer and pterygoid to be tooth-bearing palatal bones, but also observed heterodonty on the pterygoid and the palatine. The genus Macrocnemus was described in the early twentieth century by Baron von Nopcsa based on a fragmentary specimen from Monte San Giorgio 1,2. After subsequent expeditions to the Besano Formation, which crops out in the Monte San Giorgio area, resulted in the discovery of additional specimens, the taxon was more properly described 3. Unfortunately, the holotype, stored in Milan, has since been lost as it was destroyed during the Second World War 4. The phylogenetic affinities of Macrocnemus were initially unclear. Early researchers observed similarities in the shape of the cervical vertebrae with contemporaneous taxa and erected the taxon Protorosauria 5,6. Notable members of this formerly recognised 'superorder' were Tanystropheus, Protorosaurus, Macrocnemus and Prolacerta, and all these taxa have elongated cervical vertebrae. The elongation of the cervical vertebrae is expressed most extremely in the genus Tanystropheus, of which the neck is three times the length of its trunk 7. Researchers were unsure whether to place the clade closer to the Lepidosauria or to the Archosauromorpha (e.g. 7,8). Currently, the members of the Protorosauria are all considered non-archosauriform archosauromorphs (e.g. 9-11). However, the clade itself has been observed to be paraphyletic or even polyphyletic in recent phylogenetic analyses 9 and references therein. Nonetheless, the recent analyses noted above have all recovered a monophyletic Tanystropheidae at the base of Archosauromorpha that includes Macrocnemus as well as Tanystropheus, Amotosaurus, Langobardisaurus, and Tanytrachelos, with Jesairosaurus often recovered as sister taxon to the clade.

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“…The ectopterygoid bears no teeth. This was to be expected as ectopterygoidal teeth are virtually absent among archosauromorphs, but do occur in non-saurian diapsids 68 .…”

Section: Quadratojugalmentioning

confidence: 81%

Cranial morphology of the tanystropheid Macrocnemus bassanii unveiled using synchrotron microtomography

Miedema

Spiekman

Fernández

et al. 2020

Sci Rep

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“…This may indicate reduced use in load-intensive activities such as capturing and shearing prey, and an increased focus on the marginal dentition for these activities. However, maintenance of the palatal teeth at all (contrasting with most crown archosaurs [ 31 ] and with erythrosuchids [ 127 ]) may reflect the continued importance of palatal teeth in retaining smaller prey once they enter the mouth, and have corresponded with retention of a relatively flexible tongue in contrast with crown archosaurs [ 156 ]. The loss of palatal teeth during early archosauromorph evolution is, however, far from a clear, unequivocal trend.…”

Section: Discussionmentioning

confidence: 99%

“…Overall, the deep skull of Euparkeria, potentially lightened by extension of the antorbital fenestra further anteriorly than in erythrosuchids [81] and possessing recurved, cutting marginal teeth and reduced palatal teeth, at the first sight appears to represent an intermediate morphology between that of some stem taxa (e.g. Prolacerta [90]; which probably approach more closely the ancestral archosauromorph condition [156]) and early diapsids (e.g. Youngina [157]), and crown archosaurs such as loricatans (e.g.…”

Section: Diet and Evolution Of The Archosaur Feeding Apparatusmentioning

confidence: 99%

The craniomandibular anatomy of the early archosauriformEuparkeria capensisand the dawn of the archosaur skull

et al. 2020

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Archosauria (birds, crocodilians and their extinct relatives) form a major part of terrestrial ecosystems today, with over 10 000 living species, and came to dominate the land for most of the Mesozoic (over 150 Myr) after radiating following the Permian–Triassic extinction. The archosaur skull has been essential to this diversification, itself diversified into myriad forms. The archosauriform Euparkeria capensis from the Middle Triassic (Anisian) of South Africa has been of great interest since its initial description in 1913, because its anatomy shed light on the origins and early evolution of crown Archosauria and potentially approached that of the archosaur common ancestor. Euparkeria has been widely used as an outgroup in phylogenetic analyses and when investigating patterns of trait evolution among archosaurs. Although described monographically in 1965, subsequent years have seen great advances in the understanding of early archosaurs and in imaging techniques. Here, the cranium and mandible of Euparkeria are fully redescribed and documented using all fossil material and computed tomographic data. Details previously unclear are fully described, including vomerine dentition, the epiptergoid, number of premaxillary teeth and palatal arrangement. A new diagnosis and cranial and braincase reconstruction is provided, and an anatomical network analysis is performed on the skull of Euparkeria and compared with other amniotes. The modular composition of the cranium suggests a flexible skull well adapted to feeding on agile food, but with a clear tendency towards more carnivorous behaviour, placing the taxon at the interface between ancestral diapsid and crown archosaur ecomorphology, corresponding to increases in brain size, visual sensitivity, upright locomotion and metabolism around this point in archosauriform evolution. The skull of Euparkeria epitomizes a major evolutionary transition, and places crown archosaur morphology in an evolutionary context.

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“…The outer arcade is composed of single-rowed premaxillary, maxillary, and dentary tooth fields, and the inner arcade is composed of multi-rowed vomerine, palatine, and coronoid (sometimes called splenial) tooth fields ( Figure 1 ). The composition of the axolotl dentition is typical for extant and extinct tetrapods ( Matsumoto and Evans, 2017 ), yet how this complex dental system becomes established developmentally has not been addressed. The Mexican axolotl further provides an opportunity to experimentally assess the germ-layer origin of oral epithelia ( Soukup et al, 2008 ) and thus, in combination with the information on the developmental origin of the respective tooth fields, represents an eligible developmental model for the understanding of the early events in the initiating dentition.…”

Section: Introductionmentioning

confidence: 99%

Oral and Palatal Dentition of Axolotl Arises From a Common Tooth-Competent Zone Along the Ecto-Endodermal Boundary

Soukup

Kato

Yamazaki

et al. 2021

Front. Cell Dev. Biol.

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Vertebrate dentitions arise at various places within the oropharyngeal cavity including the jaws, the palate, or the pharynx. These dentitions develop in a highly organized way, where new tooth germs are progressively added adjacent to the initiator center, the first tooth. At the same time, the places where dentitions develop house the contact zones between the outer ectoderm and the inner endoderm, and this colocalization has instigated various suggestions on the roles of germ layers for tooth initiation and development. Here, we study development of the axolotl dentition, which is a complex of five pairs of tooth fields arranged into the typically tetrapod outer and inner dental arcades. By tracking the expression patterns of odontogenic genes, we reason that teeth of both dental arcades originate from common tooth-competent zones, one present on the mouth roof and one on the mouth floor. Progressive compartmentalization of these zones and a simultaneous addition of new tooth germs distinct for each prospective tooth field subsequently control the final shape and composition of the axolotl dentition. Interestingly, by following the fate of the GFP-labeled oral ectoderm, we further show that, in three out of five tooth field pairs, the first tooth develops right at the ecto-endodermal boundary. Our results thus indicate that a single tooth-competent zone gives rise to both dental arcades of a complex tetrapod dentition. Further, we propose that the ecto-endodermal boundary running through this zone should be accounted for as a potential source of instruction factors instigating the onset of the odontogenic program.

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The palatal dentition of tetrapods and its functional significance

Cited by 28 publications

References 138 publications

Cranial morphology of the tanystropheid Macrocnemus bassanii unveiled using synchrotron microtomography

Cranial morphology of the tanystropheid Macrocnemus bassanii unveiled using synchrotron microtomography

The craniomandibular anatomy of the early archosauriformEuparkeria capensisand the dawn of the archosaur skull

Oral and Palatal Dentition of Axolotl Arises From a Common Tooth-Competent Zone Along the Ecto-Endodermal Boundary

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