Cranial and dental morphology in a bohaiornithid enantiornithine with information on its tooth replacement pattern

The unique manner in which molars from members of the family Elephantidae erupt in the jaw and wear obliquely and sequentially has profound effects upon dental function and phylogenetic change within the group. Three-dimensional modeling using a “molar matrix” of elephantid dentition, and application of such models to systematic and functional studies, allows a more refined description of dental morphology. A method of examining variation within elephantid teeth is presented based on successive staging of worn molars. Results indicate that individual plates exhibit increasingly derived features with wear (relative to the systematic analysis used here), while successively worn plates exhibit successively more plesiomorphic features apically and posteriorly. Further, results indicate that the patterns developed by wear on the surface of elephantid molars are conserved throughout life despite their unique successive replacement pattern. The cheek teeth in a molar series act as a single, continuous masticating unit, here termed a “cheek tooth battery.” Overall, the tools developed here, wear staging and molar matrices, allow for a more refined understanding of morphological variation within and between elephantids, with application to more conservative elephantoid taxa.

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Review of the Indian Ocean spikefish genus Mephisto (Tetraodontiformes: Triacanthodidae)

Zootaxa ◽

10.11646/zootaxa.4802.1.5 ◽

2020 ◽

Vol 4802 (1) ◽

pp. 82-98

Author(s):

KATHERINE E. BEMIS ◽

JAMES C. TYLER ◽

PETER N. PSOMADAKIS ◽

LAUREN NEWELL FERRIS ◽

APPUKUTTANNAIR BIJU KUMAR

Keyword(s):

Indian Ocean ◽

Bay Of Bengal ◽

East Coast ◽

Andaman Sea ◽

Micro Ct ◽

Tooth Replacement ◽

Color Photograph ◽

Replacement Pattern ◽

The Indian Ocean ◽

Ct Data

We redescribe the triacanthodid spikefish Mephisto fraserbrunneri Tyler 1966 based upon eight specimens (five newly reported herein) and the first color photographs of freshly collected specimens; these data are compared with that of the single specimen of the recently described M. albomaculosus Matsuura, Psomadakis, and Mya Than Tun 2018. Both species are found in the Indian Ocean, with M. fraserbrunneri known from the Arabian Sea off the east coast of Africa to the eastern Bay of Bengal, and M. albomaculosus confirmed only from the type locality in the Andaman Sea (a color photograph of an individual M. cf. albomaculosus from the Bay of Bengal that was not retained is also presented). We describe and diagnose the genus Mephisto and provide a key to the two species based upon all available specimens. We also provide a distribution map for both species and summarize literature records. Using micro-CT data, we show that Mephisto fraserbrunneri replaces teeth intraosseously, which suggests this tooth replacement pattern is plesiomorphic for Tetraodontiformes.

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Dentition and feeding in Placodontia: tooth replacement in Henodus chelyops

BMC Ecology and Evolution ◽

10.1186/s12862-021-01835-4 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Yannick Pommery ◽

Torsten M. Scheyer ◽

James M. Neenan ◽

Tobias Reich ◽

Vincent Fernandez ◽

...

Keyword(s):

Phylogenetic Position ◽

Single Pair ◽

Dental Morphology ◽

Tooth Replacement ◽

Dental Wear ◽

Phylogeny Analysis ◽

Synchrotron Tomography ◽

The Matrix ◽

Size And Morphology ◽

Central Cusp

Abstract Background Placodontia is a Triassic sauropterygian reptile group characterized by flat and enlarged crushing teeth adapted to a durophagous diet. The enigmatic placodont Henodus chelyops has numerous autapomorphic character states, including extreme tooth count reduction to only a single pair of palatine and dentary crushing teeth. This renders the species unusual among placodonts and challenges identification of its phylogenetic position. Results The skulls of two Henodus chelyops specimens were visualized with synchrotron tomography to investigate the complete anatomy of their functional and replacement crushing dentition in 3D. All teeth of both specimens were segmented, measured, and statistically compared to reveal that H. chelyops teeth are much smaller than the posterior palatine teeth of other cyamodontoid placodonts with the exception of Parahenodus atancensis from the Iberian Peninsula. The replacement teeth of this species are quite similar in size and morphology to the functional teeth. Conclusion As other placodonts, Henodus chelyops exhibits vertical tooth replacement. This suggests that vertical tooth replacement arose relatively early in placodont phylogeny. Analysis of dental morphology in H. chelyops revealed a concave shape of the occlusal surface and the notable absence of a central cusp. This dental morphology could have reduced dental wear and protected against failure. Hence, the concave teeth of H. chelyops appear to be adapted to process small invertebrate items, such as branchiopod crustaceans. Small gastropods were encountered in the matrix close to both studied skulls.

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Spatially restricted dental regeneration drives pufferfish beak development

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1702909114 ◽

2017 ◽

Vol 114 (22) ◽

pp. E4425-E4434 ◽

Cited By ~ 10

Author(s):

Alexandre P. Thiery ◽

Takanori Shono ◽

Daisuke Kurokawa ◽

Ralf Britz ◽

Zerina Johanson ◽

...

Keyword(s):

First Generation ◽

Lineage Tracing ◽

Oral Epithelium ◽

Dental Morphology ◽

Tooth Replacement ◽

Evolution And Development ◽

Dental Epithelium ◽

Dramatic Shift ◽

Progressive Accumulation ◽

Microct Analysis

Vertebrate dentitions are extraordinarily diverse in both morphology and regenerative capacity. The teleost order Tetraodontiformes exhibits an exceptional array of novel dental morphologies, epitomized by constrained beak-like dentitions in several families, i.e., porcupinefishes, three-toothed pufferfishes, ocean sunfishes, and pufferfishes. Modification of tooth replacement within these groups leads to the progressive accumulation of tooth generations, underlying the structure of their beaks. We focus on the dentition of the pufferfish (Tetraodontidae) because of its distinct dental morphology. This complex dentition develops as a result of (i) a reduction in the number of tooth positions from seven to one per quadrant during the transition from first to second tooth generations and (ii) a dramatic shift in tooth morphogenesis following the development of the first-generation teeth, leading to the elongation of dental units along the jaw. Gene expression and 1,1′-Dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (DiI) lineage tracing reveal a putative dental epithelial progenitor niche, suggesting a highly conserved mechanism for tooth regeneration despite the development of a unique dentition. MicroCT analysis reveals restricted labial openings in the beak, through which the dental epithelium (lamina) invades the cavity of the highly mineralized beak. Reduction in the number of replacement tooth positions coincides with the development of only four labial openings in the pufferfish beak, restricting connection of the oral epithelium to the dental cavity. Our data suggest the spatial restriction of dental regeneration, coupled with the unique extension of the replacement dental units throughout the jaw, are primary contributors to the evolution and development of this unique beak-like dentition.

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Deciduous Premolars of Paleocene Litopterns of São José De Itaboraí Basin, Rio De Janeiro, Brasil

Journal of Paleontology ◽

10.1666/09-084.1 ◽

2010 ◽

Vol 84 (5) ◽

pp. 858-867 ◽

Cited By ~ 7

Author(s):

Lílian Paglarelli Bergqvist

Keyword(s):

Rio De Janeiro ◽

Deciduous Teeth ◽

Tooth Replacement ◽

X Ray ◽

Lower Jaw ◽

Replacement Pattern ◽

Milk Teeth

The order Litopterna is represented in the São José de Itaboraí basin by four species belonging to the families Protolipternidae (Protolipterna ellipsodontoides, Miguelsoria parayirunhor and Asmithwoodwardia scotti) and Proterotheriidae (Paranisolambda prodromus). Only the deciduous teeth of P. prodromus are known so far. Isolated milk premolars are described for P. ellipsodontoides and M. parayirunhor. The known specimens assigned to P. prodromus are redescribed. No milk teeth are known for A. scotti. The upper and lower milk teeth of Protolipternidae, especially dP3, are more molarized than their successors, resembling, in several features later Proterotheriidae. They provide new support for the placement of this family within the order Litopterna. The analysis of the wear level of dp2-4/dP2-4 and X-ray images of the lower jaw of P. prodromus suggests that the second teeth of the premolar series, in upper and lower jaw, are retained milk premolars. Some information on tooth replacement pattern of P. ellipsodontoides and P. prodromus are also provided.

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