Tetrapod-like axial regionalization in an early ray-finned fish

Sallan, Lauren

doi:10.1098/rspb.2012.0784

Cited by 31 publications

(66 citation statements)

References 45 publications

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“…Therefore, we coded this genus using Platysomus gibbosus (Campbell and Phuoc, 1983). Several taxa with uncertain affinities (e.g., Tarrasius and Amphicentrum) were not included, pending their redescription or revision (Sallan, 2012;L. C. Sallan, pers.…”

Section: Phylogenetic Analysismentioning

confidence: 99%

A revision of the Middle Triassic scanilepiform fishFukangichthys longidorsalisfrom Xinjiang, China, with comments on the phylogeny of the Actinopteri

Gao

Finarelli

2014

Journal of Vertebrate Paleontology

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The scanilepiform ray-finned fish Fukangichthys longidorsalis, from the Middle Triassic non-marine Kelamayi Formation of Xinjiang, China, was previously described incompletely, with many of its morphological characteristics unnoticed or misidentified. This study provides a revision of this problematic taxon based on an extensive reexamination of the original fossil material. Newly recognized anatomical information includes a plate-like quadratojugal, a triangular dermohyal, a wedge-shaped angular, two infraorbitals, three supraorbitals, fringing fulcra on the pectoral fins, and conical, acrodin-capped teeth in the jaws. Results of a phylogenetic analysis confirmed Fukangichthys as a scanilepiform within the Neopterygii, and provided new insights into the evolution of early actinopteran fishes. Cosmoptychius, previously regarded as the oldest stemgroup neopterygian, and Brachydegma, previously hypothesized to be the oldest halecomorph, are here reinterpreted as a stem-group actinopteran and a stem-group neopterygian, respectively. Additionally, Discoserra, previously hypothesized in a position close to the Holostei/Teleostei split, is now recovered in a clade with Ebenaqua, Bobasatrania and Platysomus gibbosus, and is therefore phylogenetically distant from crown neopterygians. As a consequence, fossil candidates for divergence time calibrations within the Actinopteri require reconsideration.

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Section: Phylogenetic Analysismentioning

confidence: 99%

A revision of the Middle Triassic scanilepiform fishFukangichthys longidorsalisfrom Xinjiang, China, with comments on the phylogeny of the Actinopteri

Gao

Finarelli

2014

Journal of Vertebrate Paleontology

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“…; Bird & Mabee, ; Deschamps et al. ; Sallan, ). Terms used in the literature for region one are precaudal, abdominal, truncal or prehaemal.…”

Section: Introductionmentioning

confidence: 99%

Vertebral column regionalisation in Chinook salmon, Oncorhynchus tshawytscha

et al. 2017

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Teleost vertebral centra are often similar in size and shape, but vertebral-associated elements, i.e. neural arches, haemal arches and ribs, show regional differences. Here we examine how the presence, absence and specific anatomical and histological characters of vertebral centra-associated elements can be used to define vertebral column regions in juvenile Chinook salmon (Oncorhynchus tshawytscha). To investigate if the presence of regions within the vertebral column is independent of temperature, animals raised at 8 and 12 °C were studied at 1400 and 1530 degreedays, in the freshwater phase of the life cycle. Anatomy and composition of the skeletal tissues of the vertebral column were analysed using Alizarin red S whole-mount staining and histological sections. Six regions, termed I-VI, are recognised in the vertebral column of specimens of both temperature groups. Postcranial vertebrae (region I) carry neural arches and parapophyses but lack ribs. Abdominal vertebrae (region II) carry neural arches and ribs that articulate with parapophyses. Elastic- and fibrohyaline cartilage and Sharpey's fibres connect the bone of the parapophyses to the bone of the ribs. In the transitional region (III) vertebrae carry neural arches and parapophyses change stepwise into haemal arches. Ribs decrease in size, anterior to posterior. Vestigial ribs remain attached to the haemal arches with Sharpey's fibres. Caudal vertebrae (region IV) carry neural and haemal arches and spines. Basidorsals and basiventrals are small and surrounded by cancellous bone. Preural vertebrae (region V) carry neural and haemal arches with modified neural and haemal spines to support the caudal fin. Ural vertebrae (region VI) carry hypurals and epurals that represent modified haemal and neural arches and spines, respectively. The postcranial and transitional vertebrae and their respective characters are usually recognised, but should be considered as regions within the vertebral column of teleosts because of their distinctive morphological characters. While the number of vertebrae within each region can vary, each of the six regions is recognised in specimens of both temperature groups. This refined identification of regionalisation in the vertebral column of Chinook salmon can help to address evolutionary developmental and functional questions, and to support applied research into this farmed species.

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“…Sallan [37] interpreted this anterior haemal-arch bearing region as ‘sacral’ in the osteichthyans Tarrasius and Eusthenopteron , suggesting that a tetrapod-like Hox code underlying regionalization of the axial skeleton is plesiomorphic for jawed vertebrates and secondarily lost in some teleosts, including the developmental model Danio . The results presented here suggest that the expansion of this region has evolved several times independently within actinopterygians.…”

Section: Discussionmentioning

confidence: 99%

Regionalization of the axial skeleton in the ‘ambush predator’ guild – are there developmental rules underlying body shape evolution in ray-finned fishes?

Maxwell

Wilson

2013

BMC Evol Biol

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BackgroundA long, slender body plan characterized by an elongate antorbital region and posterior displacement of the unpaired fins has evolved multiple times within ray-finned fishes, and is associated with ambush predation. The axial skeleton of ray-finned fishes is divided into abdominal and caudal regions, considered to be evolutionary modules. In this study, we test whether the convergent evolution of the ambush predator body plan is associated with predictable, regional changes in the axial skeleton, specifically whether the abdominal region is preferentially lengthened relative to the caudal region through the addition of vertebrae. We test this hypothesis in seven clades showing convergent evolution of this body plan, examining abdominal and caudal vertebral counts in over 300 living and fossil species. In four of these clades, we also examined the relationship between the fineness ratio and vertebral regionalization using phylogenetic independent contrasts.ResultsWe report that in five of the clades surveyed, Lepisosteidae, Esocidae, Belonidae, Sphyraenidae and Fistulariidae, vertebrae are added preferentially to the abdominal region. In Lepisosteidae, Esocidae, and Belonidae, increasing abdominal vertebral count was also significantly related to increasing fineness ratio, a measure of elongation. Two clades did not preferentially add abdominal vertebrae: Saurichthyidae and Aulostomidae. Both of these groups show the development of a novel caudal region anterior to the insertion of the anal fin, morphologically differentiated from more posterior caudal vertebrae.ConclusionsThe preferential addition of abdominal vertebrae in fishes with an elongate body shape is consistent with the existence of a conservative positioning module formed by the boundary between the abdominal and caudal vertebral regions and the anterior insertion of the anal fin. Dissociation of this module is possible, although less probable than changes in the independently evolving abdominal region. Dissociation of the axial skeleton-median fin module leads to increased regionalization within the caudal vertebral column, something that has evolved several times in bony fishes, and may be homologous with the sacral region of tetrapods. These results suggest that modularity of the axial skeleton may result in somewhat predictable evolutionary outcomes in bony fishes.

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Tetrapod-like axial regionalization in an early ray-finned fish

Cited by 31 publications

References 45 publications

A revision of the Middle Triassic scanilepiform fishFukangichthys longidorsalisfrom Xinjiang, China, with comments on the phylogeny of the Actinopteri

A revision of the Middle Triassic scanilepiform fishFukangichthys longidorsalisfrom Xinjiang, China, with comments on the phylogeny of the Actinopteri

Vertebral column regionalisation in Chinook salmon, Oncorhynchus tshawytscha

Regionalization of the axial skeleton in the ‘ambush predator’ guild – are there developmental rules underlying body shape evolution in ray-finned fishes?

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