Decision letter: The developmental relationship between teeth and dermal odontodes in the most primitive bony fish Lophosteus

The ontogenetic trajectory of a marginal jawbone of Lophosteus superbus (Late Silurian, 422 Million years old), the phylogenetically most basal stem osteichthyan, visualized by synchrotron microtomography, reveals a developmental relationship between teeth and dermal odontodes that is not evident from the adult morphology. The earliest odontodes are two longitudinal founder ridges formed at the ossification center. Subsequent odontodes that are added lingually to the ridges turn into conical teeth and undergo cyclic replacement, while those added labially achieve a stellate appearance. Stellate odontodes deposited directly on the bony plate are aligned with the alternate files of teeth, whereas new tooth positions are inserted into the files of sequential addition when a gap appears. Successive teeth and overgrowing odontodes show hybrid morphologies around the oral-dermal boundary, suggesting signal cross-communication. We propose that teeth and dermal odontodes are modifications of a single system, regulated and differentiated by the oral and dermal epithelia.

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Author response: The developmental relationship between teeth and dermal odontodes in the most primitive bony fish Lophosteus

10.7554/elife.60985.sa2 ◽

2020 ◽

Author(s):

Donglei Chen ◽

Henning Blom ◽

Sophie Sanchez ◽

Paul Tafforeau ◽

Tiiu Märss ◽

...

Keyword(s):

Bony Fish ◽

Author Response ◽

Developmental Relationship

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Dental ontogeny in the most primitive bony fish Lophosteus reveals the developmental relationship between teeth and dermal odontodes

10.1101/2020.07.14.202234 ◽

2020 ◽

Cited By ~ 1

Author(s):

Donglei Chen ◽

Henning Blom ◽

Sophie Sanchez ◽

Paul Tafforeau ◽

Tiiu Märss ◽

...

Keyword(s):

Bony Fish ◽

Ossification Center ◽

Developmental Relationships ◽

Adult Morphology ◽

Developmental Relationship ◽

Bony Plate ◽

Dental Ontogeny ◽

Synchrotron Microtomography

AbstractOntogenetic data obtained by synchrotron microtomography of a marginal jawbone of Lophosteus superbus (Late Silurian, 422 Million years old), the phylogenetically basalmost stem osteichthyan, reveal developmental relationships between teeth and ornament that are not obvious from the adult morphology. The earliest odontodes are two longitudinal founder ridges formed at the ossification center. Subsequent odontodes that are added lingually to the ridges turn into conical teeth and undergo cyclic replacement, while those added labially achieve a stellate appearance. The stellate odontodes deposited directly on the bony plate are aligned with the alternate files of the teeth. Successive odontodes overgrowing the labial tooth rows become tooth-like and the replacement teeth near to them are ornament-like. We propose that teeth and ornament are modifications of a single odontode system regulated and differentiated by the oral and dermal signals; signal cross-communication between the two domains can occur around the oral-dermal boundary.

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A new pycnodont specimen (Actinopterygii: Pycnodontiformes) from the Upper Cretaceous of Big Bend National Park, Texas, USA, confirming the bony fish genus Macropycnodon as a junior synonym of Acrotemnus

Cretaceous Research ◽

10.1016/j.cretres.2021.104797 ◽

2021 ◽

Vol 124 ◽

pp. 104797

Author(s):

Kenshu Shimada ◽

Diane S. Portillo ◽

Timothy J. Cronin

Keyword(s):

National Park ◽

Upper Cretaceous ◽

Bony Fish ◽

Junior Synonym ◽

Big Bend National Park ◽

Big Bend

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Fish larvae exploit edge vortices along their dorsal and ventral fin folds to propel themselves

Journal of The Royal Society Interface ◽

10.1098/rsif.2016.0068 ◽

2016 ◽

Vol 13 (116) ◽

pp. 20160068 ◽

Cited By ~ 16

Author(s):

Gen Li ◽

Ulrike K. Müller ◽

Johan L. van Leeuwen ◽

Hao Liu

Keyword(s):

Larval Fish ◽

Fish Larvae ◽

Fluid Dynamic ◽

Three Dimensional ◽

Reynolds Numbers ◽

Bony Fish ◽

The Body ◽

Functional Explanation ◽

Image Velocimetry ◽

Median Fins

Larvae of bony fish swim in the intermediate Reynolds number ( Re ) regime, using body- and caudal-fin undulation to propel themselves. They share a median fin fold that transforms into separate median fins as they grow into juveniles. The fin fold was suggested to be an adaption for locomotion in the intermediate Reynolds regime, but its fluid-dynamic role is still enigmatic. Using three-dimensional fluid-dynamic computations, we quantified the swimming trajectory from body-shape changes during cyclic swimming of larval fish. We predicted unsteady vortices around the upper and lower edges of the fin fold, and identified similar vortices around real larvae with particle image velocimetry. We show that thrust contributions on the body peak adjacent to the upper and lower edges of the fin fold where large left–right pressure differences occur in concert with the periodical generation and shedding of edge vortices. The fin fold enhances effective flow separation and drag-based thrust. Along the body, net thrust is generated in multiple zones posterior to the centre of mass. Counterfactual simulations exploring the effect of having a fin fold across a range of Reynolds numbers show that the fin fold helps larvae achieve high swimming speeds, yet requires high power. We conclude that propulsion in larval fish partly relies on unsteady high-intensity vortices along the upper and lower edges of the fin fold, providing a functional explanation for the omnipresence of the fin fold in bony-fish larvae.

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