Tooth replacement in early sarcopterygians

Doeland, Mark; Couzens, Aidan M. C.; Donoghue, Philip C. J.; Rücklin, Martin

doi:10.1098/rsos.191173

Cited by 15 publications

(35 citation statements)

References 41 publications

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“…However, it is difficult to assess whether non-shedding parasymphyseal whorls are homologous due to the unclear condition in psarolepids (variably interpreted as stem sarcopterygians or stem osteichthyans (48-52)), in which a whorl is inferred (48,52) but is yet to be described. Finally, the interposition of many non-shedding stem-chondrichthyan taxa between shedding chondrichthyans and shedding osteichthyans confirms that a shedding dentition evolved twice, in two different ways, in crown-gnathostomes (7,10) (3,5,8,11,16,32,41,45,53,54).…”

Section: Discussionmentioning

confidence: 64%

Section: Discussionmentioning

confidence: 99%

“…Parasymphyseal tooth whorls in which the teeth replace via resporption and anterior rotation (10) are also known in osteichthyans (e.g. in Onychodus (10,47)), but these are phylogenetically and structurally removed from chondrichthyan tooth whorls and unlikely to be homologous. However, it is difficult to assess whether non-shedding parasymphyseal whorls are homologous due to the unclear condition in psarolepids (variably interpreted as stem sarcopterygians or stem osteichthyans (48-52)), in which a whorl is inferred (48,52) but is yet to be described.…”

Section: Discussionmentioning

confidence: 99%

“…The advent of micro-computed tomography has led to a renewed interest in tooth evolution and development in 'placoderms' (3)(4)(5) and osteichthyans (6)(7)(8)(9)(10). However, 'acanthodians', the earliest-branching members of the chondrichthyan total-group, have received comparatively little study (but see: (11)(12)(13)), despite a bewildering array of dermal oral structures (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Diverse stem-chondrichthyan oral structures and evidence for an independently acquired acanthodid dentition

Dearden

Giles

2020

Preprint

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The teeth of sharks famously form a series of parallel, continuously replacing files borne directly on the mandibular cartilages. In contrast, bony fishes possess site-specific shedding dentition borne on dermal plates. Understanding how these disparate systems evolved is challenging, not least because of poorly understood relationships and the profusion of morphologically and terminologically diverse bones, splints and whorls seen in the earliest chondrichthyans. Here we use tomographic methods to investigate the nature of mandibular structures in several early branching 'acanthodian'-grade stem-chondrichthyans. We characterise the gnathal plates of ischnacanthids as growing bones, and draw similarities between early chondrichthyan and stem gnathostome teeth and jaws. We further build the case for Acanthodopsis, a Carboniferous taxon, as an acanthodid, and show that, unexpectedly, its teeth are borne directly on the mandibular cartilage. Mandibular splints are formed from dermal bone and appear to be an acanthodid synapomorphy. The development of a unidirectionally growing dentition may be a feature of the chondrichthyan total-group. More generally, ischnacanthid and stem gnathostome gnathal plates share a common construction and are likely homologous, and shedding teeth evolved twice in gnathostomes.

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Section: Discussionmentioning

confidence: 64%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Diverse stem-chondrichthyan oral structures and evidence for an independently acquired acanthodid dentition

Dearden

Giles

2020

Preprint

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“…Synchrotron X-ray tomographic microscopy of the caudal region of the vertebral column [ 40 ] was performed at the TOMCAT beamline (X02DA) (Swiss Light Source (SLS), Paul Scherrer Institut (PSI), Villigen, Switzerland, ). Scans were acquired with 1501 projections over 180˚ at 16 keV with an exposure time of 150 ms using a 10× objective resulting in an effective voxel size of 0.65 µm [ 105 ]. Radiographs were phase-retrieved using the Paganin algorithm, tomographically reconstructed and subsequently analysed using Amira 3.1.1 software (TermoFisher, Waltham, MA, USA).…”

Section: Methodsmentioning

confidence: 99%

More Bone with Less Minerals? The Effects of Dietary Phosphorus on the Post-Cranial Skeleton in Zebrafish

Cotti

Huysseune

Koppe³

et al. 2020

IJMS

Self Cite

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Dietary phosphorus (P) is essential for bone mineralisation in vertebrates. P deficiency can cause growth retardation, osteomalacia and bone deformities, both in teleosts and in mammals. Conversely, excess P supply can trigger soft tissue calcification and bone hypermineralisation. This study uses a wide range of complementary techniques (X-rays, histology, TEM, synchrotron X-ray tomographic microscopy, nanoindentation) to describe in detail the effects of dietary P on the zebrafish skeleton, after two months of administering three different diets: 0.5% (low P, LP), 1.0% (regular P, RP), and 1.5% (high P, HP) total P content. LP zebrafish display growth retardation and hypomineralised bones, albeit without deformities. LP zebrafish increase production of non-mineralised bone matrix, and osteoblasts have enlarged endoplasmic reticulum cisternae, indicative for increased collagen synthesis. The HP diet promotes growth, high mineralisation, and stiffness but causes vertebral centra fusions. Structure and arrangement of bone matrix collagen fibres are not influenced by dietary P in all three groups. In conclusion, low dietary P content stimulates the formation of non-mineralised bone without inducing malformations. This indicates that bone formation and mineralisation are uncoupled. In contrast, high dietary P content promotes mineralisation and vertebral body fusions. This new zebrafish model is a useful tool to understand the mechanisms underlying osteomalacia and abnormal mineralisation, due to underlying variations in dietary P levels.

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The dental system of †Kazanichthys viatkensis (Actinopterygii, Acrolepididae) from the middle Permian of European Russia: palaeobiological and palaeoecological inferences

Bakaev

Johanson

LeBlanc

2023

Papers in Palaeontology

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Among ray‐finned fishes (Actinopterygii), the crushing, durophagous feeding strategy first evolved in the early Carboniferous period, with the †Eurynotiformes possessing dentitions with single layers of partially to fully fused blunt teeth. In the †‘Platysomidae’ (Permian), a new form of crushing dentition evolved (phyllodonty), in which multiple layers of superimposed crushing teeth developed intraosseously, within the jaw. The phyllodont durophagous dentition is also recovered from later‐occurring taxa originating mainly in the Mesozoic, such as the †Bobastraniiformes, the neopterygians †Pycnodontiformes and Ginglymodi, and in the teleost group †Phyllodonta. By comparison, †Kazanichthys viatkensis, an actinopterygian from the middle Permian of European Russia, is characterized by a third, putatively durophagous dentition, with anterior conical teeth and closely packed molariform teeth on the buccal dental plates (a potential similarity with eurynotiforms). Whereas the conical teeth are similar to those of basal actinopterygians, the molariform teeth superficially resemble teeth of some teleosts (Characiformes, Tetraodontiformes), but are unique among known fossil and living Actinopterygii in being crowned by anastomosing, sharp apical ridges. Teeth are ankylosed to the jaw and acrodont in implantation. There is neither evidence of plicidentine, nor cavities corresponding to intraosseous crypts. Most replacement teeth formed extraosseously, differing from the phyllodont dentition, but similar to several more phylogenetically basal actinopterygians. The dental system morphologically resembles recent Sparidae (Teleostei; Perciformes), possibly indicating a similar trophic adaptation. Based on these comparisons and patterns of wear, we propose that †K. viatkensis was a generalist durophagous feeder, with the ability to switch prey types with its unique and complex dentition.

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Tooth replacement in early sarcopterygians

Cited by 15 publications

References 41 publications

Diverse stem-chondrichthyan oral structures and evidence for an independently acquired acanthodid dentition

Diverse stem-chondrichthyan oral structures and evidence for an independently acquired acanthodid dentition

More Bone with Less Minerals? The Effects of Dietary Phosphorus on the Post-Cranial Skeleton in Zebrafish

The dental system of †Kazanichthys viatkensis (Actinopterygii, Acrolepididae) from the middle Permian of European Russia: palaeobiological and palaeoecological inferences

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