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Dupret V, Byrne HM, Castro N, Hammer Ø, Higgs KT, Long JA, Niedźwiedzki G, Qvarnström M, Stössel I, Ahlberg PE. The Bothriolepis (Placodermi, Antiarcha) material from the Valentia Slate Formation of the Iveragh Peninsula (middle Givetian, Ireland): Morphology, evolutionary and systematic considerations, phylogenetic and palaeogeographic implications. PLoS One 2023; 18:e0280208. [PMID: 36821588 PMCID: PMC9949654 DOI: 10.1371/journal.pone.0280208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 12/21/2022] [Indexed: 02/24/2023] Open
Abstract
Material of the antiarch placoderm Bothriolepis from the middle Givetian of the Valentia Slate Formation in Iveragh Peninsula, Ireland, is described and attributed to a new species, B. dairbhrensis sp. nov. A revision of the genus Bothriolepis is proposed, and its taxonomic content and previous phylogenetic analyses are reviewed, as well as the validity of morphologic characteristics considered important for the establishment of the genus, such as the shape of the preorbital recess of the neurocranium. A series of computerised phylogenetic analyses was performed, which reveals that our new species is the sister taxon to the Frasnian Scottish form B. gigantea. New phylogenetic and biogeographic analyses of the genus Bothriolepis together with comparisons between faunal assemblages reveal a first northward dispersal wave from Gondwana to Euramerica at the latest in the mid Givetian. Other Euramerican species of Bothriolepis seem to belong to later dispersal waves from Gondwana, non-excluding southward waves from Euramerica. Questions remain open such as the taxonomic validity and stratigraphic constraints for the most ancient forms of Bothriolepis in China, and around the highly speciose nature of the genus.
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Affiliation(s)
- Vincent Dupret
- Department of Organismal Biology, Uppsala University, Uppsala, Sweden
- * E-mail:
| | - Hannah M. Byrne
- Department of Organismal Biology, Uppsala University, Uppsala, Sweden
| | - Nélia Castro
- Natural History Museum, University of Oslo, Oslo, Norway
| | - Øyvind Hammer
- Natural History Museum, University of Oslo, Oslo, Norway
| | - Kenneth T. Higgs
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland
| | - Johan A. Long
- College of Science and Engineering, Flinders University, Adelaide, South Australia
| | | | - Martin Qvarnström
- Department of Organismal Biology, Uppsala University, Uppsala, Sweden
| | - Iwan Stössel
- Department of Earth Sciences, ETH Zürich, Zürich, Switzerland
| | - Per E. Ahlberg
- Department of Organismal Biology, Uppsala University, Uppsala, Sweden
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Trinajstic K, Long JA, Sanchez S, Boisvert CA, Snitting D, Tafforeau P, Dupret V, Clement AM, Currie PD, Roelofs B, Bevitt JJ, Lee MSY, Ahlberg PE. Exceptional preservation of organs in Devonian placoderms from the Gogo lagerstätte. Science 2022; 377:1311-1314. [DOI: 10.1126/science.abf3289] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The origin and early diversification of jawed vertebrates involved major changes to skeletal and soft anatomy. Skeletal transformations can be examined directly by studying fossil stem gnathostomes; however, preservation of soft anatomy is rare. We describe the only known example of a three-dimensionally mineralized heart, thick-walled stomach, and bilobed liver from arthrodire placoderms, stem gnathostomes from the Late Devonian Gogo Formation in Western Australia. The application of synchrotron and neutron microtomography to this material shows evidence of a flat S-shaped heart, which is well separated from the liver and other abdominal organs, and the absence of lungs. Arthrodires thus show the earliest phylogenetic evidence for repositioning of the gnathostome heart associated with the evolution of the complex neck region in jawed vertebrates.
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Affiliation(s)
- Kate Trinajstic
- School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
- Western Australian Museum, Welshpool, WA 6106, Australia
| | - John A. Long
- College of Science and Engineering, Flinders University, Adelaide, SA 5001, Australia
- Museum Victoria, Melbourne, VIC 3001, Australia
| | - Sophie Sanchez
- Department of Organismal Biology, Evolutionary Biology Center, Uppsala University, 75236 Uppsala, Sweden
- European Synchrotron Radiation Facility, 38000 Grenoble, France
| | - Catherine A. Boisvert
- School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Daniel Snitting
- Department of Organismal Biology, Evolutionary Biology Center, Uppsala University, 75236 Uppsala, Sweden
| | - Paul Tafforeau
- European Synchrotron Radiation Facility, 38000 Grenoble, France
| | - Vincent Dupret
- Department of Organismal Biology, Evolutionary Biology Center, Uppsala University, 75236 Uppsala, Sweden
| | - Alice M. Clement
- College of Science and Engineering, Flinders University, Adelaide, SA 5001, Australia
| | - Peter D. Currie
- Australian Regenerative Medicine Institute and EMBL Australia, Monash University, Clayton, VIC 3800, Australia
| | - Brett Roelofs
- School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Joseph J. Bevitt
- Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia
| | - Michael S. Y. Lee
- College of Science and Engineering, Flinders University, Adelaide, SA 5001, Australia
- Earth Sciences Section, South Australian Museum, Adelaide, SA 5000, Australia
| | - Per E. Ahlberg
- Department of Organismal Biology, Evolutionary Biology Center, Uppsala University, 75236 Uppsala, Sweden
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Endocast and Bony Labyrinth of a Devonian "Placoderm" Challenges Stem Gnathostome Phylogeny. Curr Biol 2021; 31:1112-1118.e4. [PMID: 33508218 DOI: 10.1016/j.cub.2020.12.046] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 11/24/2020] [Accepted: 12/23/2020] [Indexed: 11/20/2022]
Abstract
Our understanding of the earliest evolution of jawed vertebrates depends on a credible phylogenetic framework for the jawed stem gnathostomes collectively known as "placoderms".1 However, their relationships, and whether placoderms represent a single radiation or a paraphyletic array, remain contentious.2-13 This uncertainty is compounded by an uneven understanding of anatomy across the group, particularly of the phylogenetically informative braincase and brain cavity-endocast. Based on new tomographic data, we here describe the endocast and bony labyrinth of Brindabellaspis stensioi from the Early Devonian of New South Wales.14 The taxon was commonly recovered as branching near the base of placoderms.5-9,11,12,15-17 Previous studies of Brindabellaspis emphasized its resemblances with fossil jawless fishes in the braincase anatomy14 and endocast proportions1,18 and its distinctive features were interpreted as autapomorphies, such as the elongated premedian region.19 Although our three-dimensional data confirmed the resemblance of its endocast to those of jawless vertebrates, we discovered that the inner ear and endolymphatic complex display a repertoire of previously unrecognized characters close to modern or crown-group jawed vertebrates, including a pronounced sinus superior and a vertical duct that connects the endolymphatic sac and the labyrinth cavity. Both parsimony and Bayesian analyses suggest that prevailing hypotheses of placoderm relationships are unstable, with newly revealed anatomy pointing to a radical revision of early gnathostome evolution. Our results call into question the appropriateness of arthrodire-like placoderms as models of primitive gnathostome anatomy and raise questions of homology relating to key cranial features.
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Zhu YA, Lu J, Zhu M. Reappraisal of the Silurian placoderm Silurolepis and insights into the dermal neck joint evolution. ROYAL SOCIETY OPEN SCIENCE 2019; 6:191181. [PMID: 31598327 PMCID: PMC6774982 DOI: 10.1098/rsos.191181] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Accepted: 08/20/2019] [Indexed: 05/15/2023]
Abstract
Silurolepis platydorsalis, a Silurian jawed vertebrate originally identified as an antiarch, is here redescribed as a maxillate placoderm close to Qilinyu and is anteroposteriorly reversed as opposed to the original description. The cuboid trunk shield possesses three longitudinal cristae, obstanic grooves on the trunk shield and three median dorsal plates, all uniquely shared with Qilinyu. Further preparation reveals the morphology of the dermal neck joint, with slot-shaped articular fossae on the trunk shield similar to Qilinyu and antiarchs. However, new tomographic data reveal that Qilinyu uniquely bears a dual articulation between the skull roof and trunk shield, which does not fit into the traditional 'ginglymoid' and 'reverse ginglymoid' categories. An extended comparison in early jawed vertebrates confirms that a sliding-type dermal neck joint is widely distributed and other types are elaborated in different lineages by developing various laminae. Nine new characters related to the dermal neck joint are proposed for a new phylogenetic analysis, in which Silurolepis forms a clade with Qilinyu. The current phylogenetic framework conflicts with the parsimonious evolution of dermal neck joints in suggesting that the shared trunk shield characters between antiarchs and Qilinyu are independently acquired, and the sliding-type joint in Entelognathus is reversely evolved from the dual articulation in Qilinyu.
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Affiliation(s)
- You-an Zhu
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences (CAS), 142 Xi-zhi-men-wai Street, Beijing 100044, People's Republic of China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, People's Republic of China
- Subdepartment of Evolution and Development, Uppsala University, Norbyvägen 18A, 752 36 Uppsala, Sweden
| | - Jing Lu
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences (CAS), 142 Xi-zhi-men-wai Street, Beijing 100044, People's Republic of China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, People's Republic of China
| | - Min Zhu
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences (CAS), 142 Xi-zhi-men-wai Street, Beijing 100044, People's Republic of China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, People's Republic of China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Author for correspondence: Min Zhu e-mail:
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