Fig 1.
Volume renderings and volumizations of Rhynchonkos stovalli (FM-UR 1039).
Shown in dorsal view (A, B) and right lateral view (C, D). Volume renderings (A, C) depict the specimen after being submitted to HRXCT. Volumizations (B, D) show the bony elements after they have been isolated. Scale bar equals 1mm. Abbreviations: a, angular; art, articular; bo, basioccipital; d, dentary; ect, ectopterygoid; eo, exoccipital; fro, frontal; jug, jugal; lac, lacrimal; max, maxilla; n, nasal; opi, opisthotic; par, parietal; po, postorbital; pof, postfrontal; pp, postparietal; ppo, palpebral ossification; prf, prefrontal; prm, premaxilla; pte, pterygoid; sa, surangular; sm, septomaxilla; so, supraoccipital; sq, squamosal; tab, tabular; v, vomer.
Fig 2.
Ventral skull roof reconstructions and interpretive drawings of the descending flange of the prefrontals, frontals, and parietals.
Rhynchonkos stovalli (FM-UR 1039); (A, B) and Aletrimyti gaskillae, gen. et sp. nov. (FM-UR 1040); (C, D), in ventral view, based on select micro-CT images. Bold line indicates the descending flange of the prefrontal, frontal, and parietal. Grey line indicates a depression in the bone. Not shown to scale. Abbreviations: f, frontal; p, parietal; pin, pineal foramen; prf, prefrontal; V1, foramen for the ophthalmic branch of the trigeminal nerve.
Fig 3.
Isolated elements of the palate and neighboring elements in ventral view.
A, Rhynchonkos stovalli (FM-UR 1039); B, Aletrimyti gaskillae, gen. et sp. nov. (FM-UR 1040); C, Dvellecanus carrolli, gen. et sp. nov. (UCMP 202940). Reconstructed from HRXCT images. Scale bar equals 1mm. Abbreviations: ect, ectopterygoid; epi, epipterygoid; max, maxilla; pal, palatine; prm, premaxilla; ps, parasphenoid; pte, pterygoid; q, quadrate; v, vomer.
Fig 4.
Interpretive drawings of Rhynchonkos stovalli (FM-UR 1039).
A, medial view; B, right lateral view. Lower jaw has been removed to better reveal palate and cheek elements. Scale bar equals 1mm. Abbreviations: bo, basioccipital; eo, exoccipital; epi, epipterygoid; fro, frontal; jug, jugal; lac, lacrimal; mab, ‘median anterior braincase bone’; max, maxilla; n, nasal; opi, opisthotic; par, parietal; pls, pleurosphenoid; po, postorbital; pof, postfrontal; pp, postparietal; ppo, palpebral ossification; prf, prefrontal; prm, premaxilla; pro, prootic; ps, parasphenoid; pte, pterygoid; se, sphenethmoid; sm, septomaxilla; so, supraoccipital; sq, squamosal; sta, stapes; tab, tabular; v, vomer.
Fig 5.
Isolated elements of the lower jaw and quadrate.
Shown in right lateral (A, C), left lateral (B), and medial (D, E, F) views. A, D, Rhynchonkos stovalli (FM-UR 1039); B, E, Aletrimyti gaskillae, gen. et sp. nov. (FM-UR 1040); C, F, Dvellecanus carrolli, gen. et sp. nov. (UCLA-VP 2940). Reconstructed from HRXCT images. Scale bar equals 1mm. Abbreviations: a, angular; art, articular; co1, anterior coronoid; co2, posterior coronoid; d, dentary; pa, prearticular; sa, surangular; sp, splenial; spp, post-splenial.
Fig 6.
Isolated braincase elements of Rhynchonkos stovalli (FM-UR 1039).
Shown in right lateral (A), dorsal (B), right anterolateral oblique (C), and left posterolateral oblique (D) views. Surrounding elements have been removed to expose braincase. Scale bars equal 1mm. Abbreviations: bo, basioccipital; eo, exoccipital; mab, ‘median anterior braincase bone’; opi, opisthotic; pls, pleurosphenoid; pro, prootic; ps, parasphenoid; se, sphenethmoid; si, ossification of the subiculum infundibulum; so, supraoccipital; sta, stapes; II, optic nerve foramen; III, oculomotor nerve foramen; IV, trochlear nerve foramen; V, fenestra prootica; X, foramen for the vagus nerve and jugular vein; XII, hypoglossal nerve foramen.
Fig 7.
Volume renderings and volumizations of Aletrimyti gaskillae, gen. et sp. nov. (FM-UR 1040).
Shown in dorsal view (A, B) and left lateral view (C, D). Volume renderings (A, C) depict the specimen after being submitted to HRXCT. Volumizations (B, D) show the bony elements after they have been isolated. Scale bar equals 1mm. Abbreviations: a, angular; bo, basioccipital; d, dentary; ect, ectopterygoid; eo, exoccipital; fro, frontal; jug, jugal; lac, lacrimal; max, maxilla; n, nasal; opi, opisthotic; pal, palatine; par, parietal; po, postorbital; pof, postfrontal; pp, postparietal; ppo, palpebral ossification; prf, prefrontal; prm, premaxilla; pte, pterygoid; q, quadrate; qj, quadratojugal; sa, surangular; sm, septomaxilla; so, supraoccipital; sq, squamosal; sta, stapes; tab, tabular; v, vomer.
Fig 8.
Interpretive drawings of Aletrimyti gaskillae, gen. et sp. nov. (FM-UR 1040).
A, medial view; B, right lateral view. Lower jaw has been removed to better reveal palate and cheek elements. Scale bar equals 1mm. Abbreviations: bo, basioccipital; eo, exoccipital; fro, frontal; jug, jugal; lac, lacrimal; mab, ‘median anterior braincase bone’; max, maxilla; n, nasal; opi, opisthotic; par, parietal; pls, pleurosphenoid; po, postorbital; pof, postfrontal; pp, postparietal; ppo, palpebral ossification; prf, prefrontal; prm, premaxilla; pro, prootic; ps, parasphenoid; pte, pterygoid; q, quadrate; se, sphenethmoid; sm, septomaxilla; so, supraoccipital; sq, squamosal; sta, stapes; tab, tabular; v, vomer.
Fig 9.
Isolated braincase elements of Aletrimyti gaskillae, gen. et sp. nov. (FM-UR 1040).
Shown in right lateral (A), dorsal (B), right anterolateral oblique (C), and right posterolateral oblique (D) views. Surrounding elements have been removed to expose braincase. Scale bars equal 1mm. Abbreviations: bo, basioccipital; eo, exoccipital; mab, ‘median anterior braincase bone’; opi, opisthotic; pls, pleurosphenoid; pro, prootic; ps, parasphenoid; se, sphenethmoid; si, ossification of the subiculum infundibulum; so, supraoccipital; sta, stapes; II, optic nerve foramen; III, oculomotor nerve foramen; IV, trochlear nerve foramen; V, fenestra prootica; X, foramen for the vagus nerve and jugular vein; XII, hypoglossal nerve foramen.
Fig 10.
Volume renderings and volumizations of Dvellecanus carrolli, gen. et sp. nov. (UCMP 202940).
Shown in dorsal view (A, B) and right lateral view (C, D). Volume renderings (A, C) depict the specimen after being submitted to HRXCT. Volumizations (B, D) show the bony elements after they have been isolated. Scale bar equals 1mm. Abbreviations: a, angular; d, dentary; fro, frontal; jug, jugal; lac, lacrimal; max, maxilla; n, nasal; occ, occipital complex; opi, opisthotic; pal, palatine; par, parietal; po, postorbital; pof, postfrontal; pp, postparietal; ppo, palpebral ossification; prf, prefrontal; prm, premaxilla; pte, pterygoid; q, quadrate; qj, quadratojugal; sa, surangular; sm, septomaxilla; so, supraoccipital; sq, squamosal; sta, stapes; tab, tabular.
Fig 11.
Interpretive drawings of Dvellecanus carrolli, gen. et sp. nov. (UCMP 202940).
A, medial view; B, right lateral view. Lower jaw has been removed to better reveal palate and cheek elements. Hashed line indicates presumed ventral border of the squamosal. Scale bar equals 1mm. Abbreviations: ect, ectopterygoid; fro, frontal; jug, jugal; lac, lacrimal; mab, ‘median anterior braincase bone’; max, maxilla; n, nasal; occ, occipital complex; opi, opisthotic; pal, palatine; par, parietal; pls, pleurosphenoid; po, postorbital; pof, postfrontal; pp, postparietal; ppo, palpebral ossification; prf, prefrontal; prm, premaxilla; pro, prootic; ps, parasphenoid; pte, pterygoid; q, quadrate; se, sphenethmoid; sm, septomaxilla; so, supraoccipital; sq, squamosal; sta, stapes; tab, tabular; v, vomer.
Fig 12.
Isolated braincase elements of Dvellecanus carrolli, gen. et sp. nov. (UCMP 202940).
Shown in right lateral (A), dorsal (B), left anterolateral oblique (C), and left posterolateral oblique (D) views. Surrounding elements have been removed to expose braincase. Scale bars equal 1mm. Abbreviations: occ, occipital complex; opi, opisthotic; pls, pleurosphenoid; pro, prootic; ps, parasphenoid; se, sphenethmoid; si, ossification of the subiculum infundibulum; so, supraoccipital; sta, stapes; II, optic nerve foramen; III, oculomotor nerve foramen; IV, trochlear nerve foramen; V, fenestra prootica; X, foramen for the vagus nerve and jugular vein.
Fig 13.
Isolated elements of the right otic capsule of Dvellecanus carrolli, gen. et sp. nov. (UCMP 202940).
Scan (A) and interpretive line drawing (B) in ventromedial oblique view, with the anterior oriented to the left. Surrounding braincase elements have been removed to expose the otic capsule. Scale bar equals 1mm. Abbreviations: ant semi, groove for the anterior semicircular canal; cr inf, crista interfenestralis; fen vest, fenestra vestibuli; hor semi, groove for the horizontal semicircular canal; lag cr, lagenar crest; lag rec, lagenar recess; opi, opisthotic; pro, prootic; rec scala tymp, recessus scala tympani; V, fenestra prootica; X, foramen for the vagus nerve and jugular vein.
Fig 14.
Reconstructions of the sphenethmoid and the descending flange of the frontal and parietal.
Specimens previously attributed to Rhynchonkos (A, C, E) and select microsaurs (B, D, F) in right lateral view. A, Aletrimyti gaskillae, gen. et sp. nov. (FM-UR 1040); B, Nannaroter mckinziei (OMNH 73107); C, Rhynchonkos stovalli (FM-UR 1039); D, Micraroter erythrogeios (FM-UR 2311); E, Dvellecanus carrolli, gen. et sp. nov. (UCMP 202940); F, Huskerpeton englehorni (UNSM 32144). Dashed line indicates the bony margins of the orbit. Scale bars equal 1mm. Abbreviations: fro, frontal; par, parietal; ps, parasphenoid; se, sphenethmoid; II, optic nerve foramen.
Table 1.
Skull measurements (in millimeters) of Rhynchonkos stovalli (FM-UR 1039), Aletrimyti gaskillae, gen. et sp. nov. (FM-UR 1040), Dvellecanus carrolli, gen. et sp. nov. (UCMP 202940), and select microsaurs (Nannaroter mckinziei (OMNH 73107), Microroter erythrogeios (FM-UR 2311), and Huskerpeton englehorni (UNSM 32144)).
Fig 15.
Posterior braincases of selected tetrapods in dorsal view, showing ossifications of the synotic tectum.
Interpretive line drawings (A-E) and volumizations (F-I). A, Limnoscelis palustris, after [42]; B, Aerosaurus cf. A. wellesi, after [43]; C, Captorhinus laticeps, after [44]; D, Petrolacosaurus kansensis, after [45]; E, Youngina capensis, after [46]; F, Huskerpeton englehorni (UNSM 32144); G, Rhynchonkos stovalli (FM-UR 1039); H, Aletrimyti (FM-UR 1040); I, Dvellecanus (UCMP 202940). Images not to scale. Abbreviations: eo, exoccipital; lap, lateral ascending process; map, median ascending process; opi, opisthotic; ot, otic; pop, posterior process; pro, prootic; so, supraoccipital; sta, stapes.