A Permian fish reveals widespread distribution of neopterygian-like jaw suspension

Abstract
Data availability
Article and author information
Metrics

Abstract

The actinopterygian crown group (comprising all living ray-finned fishes) originated by the end of the Carboniferous. However, most late Paleozoic taxa are stem actinopterygians, and broadly resemble stratigraphically older taxa. The early Permian †Brachydegma caelatum is notable for its three-dimensional preservation and past phylogenetic interpretations as a nested member of the neopterygian crown. Here, we use computed microtomography to redescribe †Brachydegma, uncovering an unanticipated combination of primitive (e.g., aortic canal; immobile maxilla) and derived (e.g., differentiated occipital ossifications; posterior stem of parasphenoid; two accessory hyoidean ossifications; double jaw joint) dermal and endoskeletal features relative to most other Paleozoic actinopterygians. Some of these features were previously thought to be restricted to the neopterygian crown. The precise phylogenetic position of †Brachydegma is unclear, with placements either on the polypterid stem, or as an early-diverging stem neopterygian. However, our analyses decisively reject previous placements of †Brachydegma in the neopterygian crown. Critically, we demonstrate that key-endoskeletal components of the hyoid portion of the suspensorium of crown neopterygians appeared deeper in the tree than previously thought.

Data availability

μCT raw and/or derived data are available on Morphosource. Links to parent directories for each studied specimen are given below.†Brachydegma caelatum (MCZ VPF 6503): www.morphosource.org/concern/media/000440974†Brachydegma caelatum (MCZ VPF 6504): www.morphosource.org/concern/media/000441020†Pteronisculus gunnari (NHMD VP 73588A): www.morphosource.org/concern/media/000441157†Parasemionotidae indet. (NHMD VP 74424A): www.morphosource.org/concern/media/000441197Acipenser brevirostrum (UMMZ 64250): www.morphosource.org/concern/media/000441184Phylogenetic matrix and trees available through Dryad at: doi.org/10.5061/dryad.jsxksn0bz

The following data sets were generated

Article and author information

Author details

Thodoris Argyriou

Muséum National d'Histoire Naturelle, Paris, France

For correspondence
t.argyriou@lrz.uni-muenchen.de

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-2036-5088
Sam Giles

School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom

Competing interests
The authors declare that no competing interests exist.
Matt Friedman

Museum of Paleontology, Department of Earth and Environmental Sciences, University of Michigan-Ann Arbor, Ann Arbor, United States

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-0114-7384

Funding

Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (P1ZHP3_168253)

Thodoris Argyriou

Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (P2ZHP3_184216)

Thodoris Argyriou

Alexander von Humboldt-Stiftung

Thodoris Argyriou

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.