A Permian fish reveals widespread distribution of neopterygian-like jaw suspension
- Paleontological Institute and Museum, University of Zurich, Switzerland
- CR2P, MNHN-CNRS-Sorbonne Universitée, Muséum National d'Histoire Naturelle, France
- Department of Earth and Environmental Sciences, Paleontology & Geobiology, Ludwig-Maximilians-Universität München, Germany
- GeoBio-Center, Ludwig-Maximilians-Universität München, Germany
- School of Geography, Earth and Environmental Sciences, University of Birmingham, United Kingdom
- Scientific Associate, The Natural History Museum, United Kingdom
- Museum of Paleontology and Department of Earth and Environmental Sciences, University of Michigan, United States
Figures
Figure 1
Previously hypothesized phylogenetic placements of †Brachydegma caelatum.
Simplified trees given contain an indicative subset of taxa common to all published phylogenetic hypotheses.
Figure 2
External anatomy of †Brachydegma caelatum holotype (MCZ VPF-6503), right lateral view.
Specimen photograph (A) and weighted-line drawing (B). Abbreviations: ?, uncertain; ?ao, possible antorbital; ang, angular; aop, accessory opercles; cl, cleithrum; dhy + hm, dermohyal overlying hyomandibula; dnt, dentary; dpt, dermopterotic; dsp, dermosphenotic; fr, frontal; io, infraorbital; ju, jugal; la, lachrymal; lexsc, lateral extrascapular; lg, lateral gular; mg, median gular; mx, maxilla; o supo, overlap areas on frontal for supraorbitals; op, opercle; pa, parietal; pcl, postcleithrum; pop, preopercle; pscl, presupracleithrum; ptmp, posttemporal; qj, quadratojugal; rbr, branchiostegal rays; scl, supracleithrum; sop, suboperculum; subo, suborbitals; supo, supraorbital. Abbreviations preceded by l or r indicate left or right structure, respectively. Dashed lines indicate a missing margin; hatching indicates a broken surface; gray tone indicates matrix. Scale bar equals 20 mm.
© 2022, President and Fellows of Harvard College. Specimen photograph reproduced with permission from Museum of Comparative Zoology, Harvard University. It is not covered by the CC-BY 4.0 license and further reproduction of this panel would need permission from the copyright holder.
Figure 3
External anatomy of †Brachydegma caelatum holotype (MCZ VPF-6503), left lateral view.
Specimen photograph (A) and weighted-line drawing (B). Abbreviations: ?, uncertain; ang, angular; aop, accessory opercle; dnt, dentary; dpt, dermopterotic; dsp, dermosphenotic; fr, frontal; ju, jugal; lexsc, lateral extrascapular; mx, maxilla; na, nasal; o mx, overlap area on the preopercle for the maxilla; op, opercle; pa, parietal; pal, palate; pmx, premaxilla; pop, preopercle; qj, quadratojugal; rbr, branchiostegal ray; sop, subopercle. Dashed lines indicate a missing margin; hatching indicates a broken surface; gray tone indicates matrix. Scale bar equals 20 mm.
© 2022, President and Fellows of Harvard College. Specimen photograph reproduced with permission from Museum of Comparative Zoology, Harvard University. It is not covered by the CC-BY 4.0 license and further reproduction of this panel would need permission from the copyright holder.
Figure 4
External anatomy of †Brachydegma caelatum holotype (MCZ VPF-6503), dorsal and ventral views.
Specimen photograph (A) and weighted-line drawing (B) in dorsal view. Specimen photograph (C) and weighted-line drawing (D) in ventral view. Abbreviations: ?, uncertain; ?ao, antorbital; ang, angular; aop, accessory opercle; cl, cleithrum; dnt, dentary; dpt, dermopterotic; dsp, dermosphenotic; fr, frontal; ju, jugal; la, lachrymal; lexsc, lateral extrascapular; lg, lateral gular; mg, median gular; mx, maxilla; na, nasal; o supo, overlap areas on frontal for supraorbitals; op, opercle; pa, parietal; pmx, premaxilla; pop, preopercle; pscl, presupracleithrum; ptmp, posttemporal; qj, quadratojugal; rbr, branchiostegal rays; scl, supracleithrum; sop, subopercle. Abbreviations preceded by l or r indicate left or right structure, respectively. Dashed lines indicate a missing margin; hatching indicates a broken surface; gray tone indicates matrix. Scale bar equals 20 mm.
© 2022, President and Fellows of Harvard College. Specimen photograph reproduced with permission from Museum of Comparative Zoology, Harvard University. It is not covered by the CC-BY 4.0 license and further reproduction of this panel would need permission from the copyright holder.
Figure 5
Braincase and parasphenoid of †Brachydegma caelatum.
Type specimen (MCZ VPF-6503) in (A) right lateral, (B) dorsal, (C) ventral, (D) posterior views; (E) line drawing of D with separate ossifications color coded. Paratype (MCZ VPF-3504) in (F) right lateral, (G) dorsal, (H) ventral, (I) posterolateral view with separate ossifications color coded; (J) line drawing of H with separate ossifications color coded, (L) composite reconstruction of preserved aspects of the braincase in lateral view with separate ossifications color coded. Abbreviations: II, orbital opening; aoca, anterior opening or aortic canal; aocp, posterior opening of aortic canal; apal, furrows for suspension of palate or parabasal canals; asp, ascending process of parasphenoid; boc, basioccipital; exo, exoccipitals; fm, foramen magnum; not, notochordal opening; osph, orbitosphenoid; pmy, posterior myodome; pspf, median furrow of parasphenoid; pspk, ventral keel of parasphenoid; spig, spiracular groove. Dashed lines indicate a missing margin. Scale bars equal 10 mm.
© 2022, President and Fellows of Harvard College. Specimen renderings reproduced with permission from Museum of Comparative Zoology, Harvard University. It is not covered by the CC-BY 4.0 license and further reproduction of this panel would need permission from the copyright holder.
Figure 6
Palatal complex and maxilla of †Brachydegma caelatum.
Type specimen (MCZ VPF-6503): (A) Palatal complex and ‘labial element’ in lateral view; palatal complex and maxilla in medial (B) and (C) ventral views; cross sections demarcated by arrows in A, B, C showing the relationship of palatal complex and maxilla at (D) the level of lateral process and (E) the level of the orbital notch. (F) Lateral view of the ossified labial element; (G) anterior view of the same element. Paratype (MCZ VPF-6504): (H) palatal complex and maxilla in medial view; (I) palatal complex in lateral view; (J) maxilla in ventromedial view. (L) Schematic reconstruction of palatal complex in lateral view. (M) Schematic reconstruction of maxilla in ventromedial view. Abbreviations: avm, accessory vomer; calg, canal for the passage of ligaments; lbe, ossified ‘labial element’; ltp, lateral process of the ectopterygoid; mptf, metapterygoideal flange; mx, maxilla; mxhl, horizontal lamina of maxilla; mxp, ethmoid articulation of maxilla; qd, quadrate; vpl, ventrolateral palatal lamina. Scale bars equal 10 mm.
© 2022, President and Fellows of Harvard College. Specimen renderings reproduced with permission from Museum of Comparative Zoology, Harvard University. They are not covered by the CC-BY 4.0 license and further reproduction of this panel would need permission from the copyright holder.
Figure 7
Suspensorium and lower jaw of †Brachydegma caelatum.
Right palatal complex and suspensorium of type specimen (MCZ VPF-6503) shown as preserved in (A) lateral and (B) medial views. Paratype (MCZ VPF-6504): right hyomandibula in (C) lateral and (D) medial views; (E) left ceratohyal in lateral view. Right lower jaw of type specimen in (F) lateral, (G) dorsal, and (H) medial views. Abbreviations: VIIhm, hyomandibular trunk of facial nerve; adf, adductor fossa; art, articular; chy, ceratohyal; chyg, arterial groove; dhy, dermohyal; dnt, dentary; hh, hypohyal; hm, hyomandibula; mxs, maxillary shelf on dentary; opp, opercular process; pal, palatal complex; qf, quadrate facets; qj?, putative quadratojugal; sang, surangular; sy, symplectic; syf, symplectic fossa. Scale bars equal 10 mm.
© 2022, President and Fellows of Harvard College. Specimen renderings reproduced with permission from Museum of Comparative Zoology, Harvard University. They are not covered by the CC-BY 4.0 license and further reproduction of this panel would need permission from the copyright holder.
Figure 8
Accessory hyoidean ossifications in †Brachydegma caelatum and other actinopterygians.
†Brachydegma caelatum type specimen (MCZ VPF-6503): (A) left suspensorium shown as preserved in lateral view; (B) posterior view of quadrate and articular; (C) anterior and (D) anterolateral detail of symplectic; (E) line drawing of D. †Parasemionotidae indet. (NHMD 74424A): (F) left suspensorium shown as preserved in lateral view; in (G) anterior and (H) lateral detail of symplectic; (I) posterior view of quadrate and articular; †Pteronisculus gunnari (NHMD 73588A): (J) right suspensorium in mirrored lateral view; (K) anterior and (L) lateral detail of symplectic; (M) posterior view of quadrate and articular; Acipenser brevirostrum (UMMZ 64250): (N) left suspensorium in lateral view; (O) anterior and (P) lateral detail of ‘symplectic’; (Q) posterior view of palatoquadrate and mackel’s cartilage. Abbreviations: afmd, groove for afferent mandibular artery; art, articular; chy, ceratohyal; cnd, anterior condyle of symplectic; ih, interhyal; mk, Meckel’s cartilage; pq, palatoquadrate; qd, quadrate; qdgr, posterior groove on quadrate; sy, symplectic; syf, symplectic fossa; vpsy, ventral process of symplectic. Scale bars for A, B, F, I, J, M–Q equal 10 mm; scale bars for C–E, G, H, K, L equal 5 mm.
© 2022, President and Fellows of Harvard College. Specimen renderings of †Brachydegma reproduced with permission from Museum of Comparative Zoology, Harvard University. They are not covered by the CC-BY 4.0 license and further reproduction of this panel would need permission from the copyright holder.
Figure 9
Branchial anatomy of †Brachydegma caelatum.
Type specimen (MCZ VPF-6503): (A) right and (B) left lateral views of complete branchial and ventral hyoid skeleton shown as preserved; (C) branchial arches of left side in medial view; (D) ventral view of preserved branchial elements of paratype (MCZ VPF-6504); (E) composite reconstruction of gill skeleton with branchial arches spaced and splayed ventrally. Abbreviations: bb, basibranchial; bb/bh?, basibranchial or basihyal; cb1–5, ceratobranchial 1–5; chy, ceratohyal; ep1–4, epibranchial 1–4; gr, gill rakers; hb1–4, hypobranchial 1–4; hh, hypohyal; ipb1–3, infrapharyngobranchial 1–3; spb1,2, suprapharyngobranchial 1,2. Scale bars equal 10 mm.
© 2022, President and Fellows of Harvard College. Specimen renderings reproduced with permission from Museum of Comparative Zoology, Harvard University. They are not covered by the CC-BY 4.0 license and further reproduction of this panel would need permission from the copyright holder.
Figure 10
Pectoral fin and axial anatomy of †Brachydegma caelatum.
Type specimen (MCZ VPF-6503): (A) Right pectoral girdle in lateral view; (B) anterior view of right cleithrum; (C) right pectoral girdle in medial view; (D) right scapulocoracoid and reconstructed fin ossifications in medial view; (E) line drawing of D with dotted line indicating the conceived course of the mesocoracoid arch; (F) right scapulocoracoid and reconstructed fin ossifications in medial view; (G) scapulocoracoid and cleithrum in posterior view; (H) anterior axial skeleton; (I) anterodorsal view of fused arcual element; (J) medial view of left basidorsal; (K) medial view of lateral line scale. Abbreviations: adp, anterodorsal process of scale; bd, basidorsal; bdf, medial furrow on basidorsal; bds, hemi-neural spine; bv, basiventral; cl, cleithrum; clv, clavicle; dmca, dorsal limit of the mesocoracoid arch; fcpl, facet for the coracoid plate; ll, lateral line pore; pap, parapophysis; pbl, post-branchial lamina; pcl, postcleithrum; pg, articular peg of scale; ppt?, putative propterygium; pzg, prezygapophysis; rd, radials; scc, scapulocoracoid; sccm, middle (articular) region of scapulocoracoid; scf, supracoracoid foramen; scl, supracleithrum; vmca, ventral limit of the mesocoracoid arch. Dashed lines represent hypothetical margins of mesocoracoid arch. Scale bars for A–H equal 10 mm; scale bars for I–K equal 5 mm.
© 2022, President and Fellows of Harvard College. Specimen renderings reproduced with permission from Museum of Comparative Zoology, Harvard University. They are not covered by the CC-BY 4.0 license and further reproduction of this panel would need permission from the copyright holder.
Figure 11
Strict consensus of the 1412 most parsimonious trees of 1652 steps for 117 taxa and 300 equally weighted characters.
Consistency index = 0.203, retention index = 0.66. Numbers above nodes indicate Bremer values above 1. Numbers below nodes indicate bootstrap percentages above 50%. Selected node optimizations are as follows: (a) (Actinopterygii total group): C.6 (1→0); C.29 (0→1,2); C.43 (0→1); C.45 (1→0); C.46 (0→1); C.54 (0→1); C.57 (0→1); C.63 (1→0); C.64 (0→1); C.69 (0→1); 70 (0→1); C.77 (0→1); C.79 (0→1); C.90 (0→1); C.109 (0→1); C.139 (0→1); C.152 (0→1); C.199 (0→1); C.215 (0→1); C.257 (0→1); C.258 (0→1); C.264 (0→1); (b) (Actinopterygii crown group): C.67 (1→0); C.101 (0→1); C.103 (0→1); C.107 (0→1); C.157 (0→2); C.174 (0→2); (c) (†Brachydegma + (†Birgeriidae+(†Scanilepiforms + †Polypteridae))): C.45 (1→0); C.55 (0→3); C.158 (0→1); (d) (Chondrostei + †Saurichthyiformes): C.14 (1→0); C.111 (1→2); C.123 (1→0); C.210 (1→0); (e) (Neopterygii crown group): C.53 (0→1); C.56 (0→1); C.73 (0→1); C.74 (0→1); C.119 (0→1); C.180 (0→1); C.219 (0→1); C.287 (0→1); (f) (Teleostei total group): C.9 (0→1); C.47 (1→0); C.55 (3→1); C.168 (0→1); C.169 (0→1); C.225 (0→1); C.270 (0→1); (g) (Halecomorphi + †Watsonulus): C.75 (0→1); C.76 (0→1); C.97 (0→1); C.135 (0→1); C.220 (1→0); C.280 (1→0); (h) ((†Dapediidae +†Pycnodontiformes) + †Tetragonolepis): C.59 (2→1); C.223 (0→1); C.255 (0→2); C.266 (0→1); C.278 (0→1); C.284 (0→1); C.285 (0→1); C.289 (0→1).
Figure 12
Evolutionary morphology of accessory hyoidean elements of actinopterygians.
Simplified evolutionary hypothesis from Figure 11. Nodes are as follows: (A) stem Actinopterygii; (B) †Brachydegma + Polypteridae; (C) Actinopteri; (D) Neopterygii; (E) Teleostei; (F) †Pycnodontiformes; (G) Holostei. Sources of anatomical information: †Pteronisculus, †Brachydegma, Acipenser, †Parasemionotidae indet, this work; Polypterus (Allis, 1922; Jollie, 1984); †Pholidophorus gervasuttii (Arratia, 2013); Hiodon, with cartilaginous interhyal omitted as it does not articulate with the hyomandibula (Hilton, 2002); †Neoproscinetes (Nursall and Maisey, 1987; Gardiner et al., 1996); Lepisosteus (Grande, 2010); Amia (Grande and Bemis, 1998). Drawings not to scale.
Appendix 1—figure 1
†Brachydegma caelatum paratype specimen (MCZ VPF-6504).
Compressed specimen in (A) dorsolateral and (B) ventrolateral (bottom) views.
© 2022, President and Fellows of Harvard College. Specimen photographs reproduced with permission from Museum of Comparative Zoology, Harvard University. They are not covered by the CC-BY 4.0 license and further reproduction of this panel would need permission from the copyright holder.
Appendix 1—figure 2
3D-reconstructed portions of †Brachydegma caelatum.
Type specimen (MCZ VPF-6503): (A) right lateral view of specimen; (B) geometry of reconstructed endoskeletal elements; (C) complete reconstruction of right side of the specimen (slightly enlarged); paratype specimen (MCZ VPF-6504): (D) left dorsolateral view of the specimen; (E) geometry of reconstructed endoskeletal elements; (F) complete reconstruction in left laterodorsal view. Abbreviations: asc, ascending process of parasphenoid; chy, ceratohyal; cl, cleithrum; clv, clavicle; dnt, dentary; exo, exoccipitals; hm, hyomandibula; mg, median gular; mx, maxilla; osph, orbitosphenoid portion of braincase; pal, palatal complex; pcl, postcleithrum; psp, parasphenoid; qd, quadrate; sc, scales; scl, supracleithrum; sy, sympectic.
© 2022, President and Fellows of Harvard College. Specimen images reproduced with permission from Museum of Comparative Zoology, Harvard University. They are not covered by the CC-BY 4.0 license and further reproduction of this panel would need permission from the copyright holder.
Appendix 1—figure 3
Agreement subtree (one of 23) resulting from parsimony analysis using equal weights and without constraining the topology of †Brachydegma.
It contains 104 out of 117 taxa. Pruned taxa: †Onychodus jandermarrai; †Styloichthys changei; †Guiyu oneiros; †Psarolepis romeri; †Meemania eos; †Donnrosenia schaefferi; †Howqualepis rostridens; †Moythomasia durgaringa; †Melanecta anneae; †Beishanichthys brevicaudalis; †Scopulipiscis saxciput; †Dapedium noricum; †Mesturus sp. Lettered nodes as in text Figure 11.
Appendix 1—figure 4
Strict consensus of the 1740 most parsimonious trees of 1646 steps for 116 taxa and 300 equally weighted characters.
†Brachydegma was excluded. Consistency index =0.204, retention index =0.661. Numbers above nodes indicate Bremer values above 1. Numbers below nodes indicate bootstrap percentages above 50%.
Appendix 1—figure 5
Strict consensus of the 44 best fit trees (fit score =68.77) resulting from analyses using implied weights with a K=12.
Selected node optimizations are as follows: (a) (Actinopterygii total group): C.43 (0→1); C.45 (1→0); C.139 (0→1); C.199 (0→1); (b) (Actinopterygii crown group): C.67 (1→0); C.101 (0→1); C.107 (0→1); C.157 (0→2); C.158 (0→1); C.174 (0→2); C.262 (0→1); (c) (†Brachydegma + Neopterygii total group): C.116 (0→1); C.124 (0→1); C.231 (0→1); (d) (†Hulettia + Neopterygii crown group): C56(0→1); C.73 (0→1); C.74 (0→1); C.90 (2→1); C.113 (0→1); C.119 (0→1); C.180 (0→1); C.219 (0→1); C.287 (0→1); (e) (Neopterygii crown group): C.18 (0→1); C.34 (0→1); C.149 (1→0); C.160 (0→1); C.171 (0→1); (f) (Halecomorphi + †Watsonulus): C.75 (0→1); C.76 (0→1); C.97 (0→1); C.135 (0→1); C.220 (1→0); C.280 (1→0); (g) (†Dapediidae + (†Pycnodontiformes + †Tetragonolepis)): C.28 (1→0); C.255 (0→2); C.257 (0→1); C.266 (0→1); C.278 (0→1); C.281 (0→1); C.284 (0→1); C.285 (0→1); C.293 (1→0).
Appendix 1—figure 6
Phylogenetic tree from Bayesian analysis of morphological phylogenetic dataset.
Values below nodes represent posterior probability support (BPP).
Appendix 1—figure 7
Triassic actinopterygians used for comparison with †Brachydegma.
(A), (B) †Pteronisculus gunnari (NHMD_73588_A), Early Triassic, East Greenland; (C), (D) †Parasemionotidae indet. (NHMD_74424_A), Early Triassic, East Greenland; (E) †Boreosomus reuterskioldi (MNHN.F_SVT15b), Early Triassic, Spitsbergen, Svalbard, prepared and figured by Véran, 1988; (F) magnification of jaw joint area, contained within a white box in (E). Abbreviations: ang, angular; chy, ceratohyal; hm, hyomandibula; ih, interhyal; qd, quadrate; sang, surangular; sy, symplectic. Scale bars equal 10 mm except for F where it equals 5 mm.
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A Permian fish reveals widespread distribution of neopterygian-like jaw suspension
eLife 11:e58433.
https://doi.org/10.7554/eLife.58433
