Bricks, trusses and superstructures: Strategies for skeletal reinforcement in batoid fishes (rays and skates)

3Citations
Citations of this article
9Readers
Mendeley users who have this article in their library.
Get full text

Abstract

Crushing and eating hard prey (durophagy) is mechanically demanding. The cartilage jaws of durophagous stingrays are known to be reinforced relative to non-durophagous relatives, with a thickened external cortex of mineralized blocks (tesserae), reinforcing struts inside the jaw (trabeculae), and pavement-like dentition. These strategies for skeletal strengthening against durophagy, however, are largely understood only from myliobatiform stingrays, although a hard prey diet has evolved multiple times in batoid fishes (rays, skates, guitarfishes). We perform a quantitative analysis of micro-CT data, describing jaw strengthening mechanisms in Rhina ancylostoma (Bowmouth Guitarfish) and Rhynchobatus australiae (White-spotted Wedgefish), durophagous members of the Rhinopristiformes, the sister taxon to Myliobatiformes. Both species possess trabeculae, more numerous and densely packed in Rhina, albeit simpler structurally than those in stingrays like Aetobatus and Rhinoptera. Rhina and Rhynchobatus exhibit impressively thickened jaw cortices, often involving >10 tesseral layers, most pronounced in regions where dentition is thickest, particularly in Rhynchobatus. Age series of both species illustrate that tesserae increase in size during growth, with enlarged and irregular tesserae associated with the jaws’ oral surface in larger (older) individuals of both species, perhaps a feature of ageing. Unlike the flattened teeth of durophagous myliobatiform stingrays, both rhinopristiform species have oddly undulating dentitions, comprised of pebble-like teeth interlocked to form compound “meta-teeth” (large spheroidal structures involving multiple teeth). This is particularly striking in Rhina, where the upper/lower occlusal surfaces are mirrored undulations, fitting together like rounded woodworking finger-joints. Trabeculae were previously thought to have arisen twice independently in Batoidea; our results show they are more widespread among batoid groups than previously appreciated, albeit apparently absent in the phylogenetically basal Rajiformes. Comparisons with several other durophagous and non-durophagous species illustrate that batoid skeletal reinforcement architectures are modular: trabeculae can be variously oriented and are dominant in some species (e.g. Rhina, Aetobatus), whereas cortical thickening is more significant in others (e.g. Rhynchobatus), or both reinforcing features can be lacking (e.g. Raja, Urobatis). We discuss interactions and implications of character states, framing a classification scheme for exploring cartilage structure evolution in the cartilaginous fishes.

Cited by Powered by Scopus

This article is free to access.

0Citations
4Readers
Get full text

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Cite

CITATION STYLE

APA

Clark, B., Chaumel, J., Johanson, Z., Underwood, C., Smith, M. M., & Dean, M. N. (2022). Bricks, trusses and superstructures: Strategies for skeletal reinforcement in batoid fishes (rays and skates). Frontiers in Cell and Developmental Biology, 10. https://doi.org/10.3389/fcell.2022.932341

Readers over time

‘22‘23‘2402468

Readers' Seniority

Tooltip

PhD / Post grad / Masters / Doc 4

80%

Researcher 1

20%

Readers' Discipline

Tooltip

Agricultural and Biological Sciences 2

40%

Medicine and Dentistry 1

20%

Biochemistry, Genetics and Molecular Bi... 1

20%

Earth and Planetary Sciences 1

20%

Article Metrics

Tooltip
Social Media
Shares, Likes & Comments: 9

Save time finding and organizing research with Mendeley

Sign up for free
0