Revalidation of Myobradypterygius hauthali Huene, 1927 and the phylogenetic signal within the ophthalmosaurid (Ichthyosauria) forefins

Campos, Lisandro; Fernández, Marta S.; Bosio, Victor; Herrera, Yanina; Manzo, Agustina

doi:10.1016/j.cretres.2023.105818

Cited by 1 publication

(2 citation statements)

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“…path length is measured in different units compared to the other metrics. Finally, based on the phylogenetic hypothesis presented in [24], a reconstruction of the ancestral states was made in TNT v. 1.6 [25] by mapping the network metrics as continuous characters using the built-in optimization. forefin is represented as a node, and contacts among them are depicted as links connecting the nodes.…”

Section: Methodsmentioning

confidence: 99%

“…Most of the stabilization relies on changes in the angle of attack or asynchronous pectoral fin movement [44,45]. Despite ichthyosauromorphs being axial swimmers through their evolution and having paired fins that must have acted on stability and maneuverability, the disparity of hydrofoils across thunnosaur clades has not been explored other than as an eventual source of phylogenetic or taxonomic information [24,46]. Given the functional relevance of fins as control surfaces, features such as density, clustering, or path length of their bone arrangements could be considered not only as expressions of morphological disparity but also as functional disparity among thunnosaurs and, thus, suggests different ecological niches.…”

Section: Fin Connectivity and Functional Disparitymentioning

confidence: 99%

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Bone Connectivity and the Evolution of Ichthyosaur Fins

Fernández,

Campos,

Manzo

et al. 2024

Diversity

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After the end-Triassic extinction, parvipelvian ichthyosaurs diversified and became dominant elements of marine ecosystems worldwide. By the Early Jurassic, they achieved a thunniform body plan that persisted for the last 100 m.y.a of their evolution. Diversification and extinctions of thunniform ichthyosaurs, and their swimming performance, have been studied from different perspectives. The transformation of limbs into hydrofoil-like structures for better control and stability during swimming predates thunniform locomotion. Despite their importance as control surfaces, fin evolution among thunnosaurs remains poorly understood. We explore ichthyosaur fin diversity using anatomical networks. Our results indicate that, under a common hydrofoil controller fin, the bone arrangement diversity of the ichthyosaur fin was greater than traditionally assumed. Changes in the connectivity pattern occurred stepwise throughout the Mesozoic. Coupled with other lines of evidence, such as the presence of a ball-and-socket joint at the leading edge of some derived Platypterygiinae, we hypothesize that fin network disparity also mirrored functional disparity likely associated with different capabilities of refined maneuvering. The ball-and-socket articulation indicates that this local point could be acting like a multiaxial intrafin joint changing the angle of attack and thus affecting the maneuverability, similar to the alula of flying birds. Further studies on large samples and quantitative experimental approaches would be worthy to test this hypothesis.

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Section: Methodsmentioning

confidence: 99%