Fig 1.
Familial level relationships of skinks based on Hedges [11] and percentage of species osteologically examined within each lineage.
Light gray = Lygosomoidea; Medium gray = Scincoidea; Dark gray = Acontoidea. The piecharts illustrate the relative percentage of species that have been cranially described within each family (see S1 Appendix). No skull anatomy descriptions currently exist for ristellids or ateuchosaurids. The ratio below each piechart represents the number of species osteologically examined out of the total number of species within each family (total numbers [10]).
Fig 2.
Articulated skulls of Trachylepis laevis (left; CAS 254838), T. sulcata (center; MCZA-28066) and T. gonwouoi (right; BYU 573530).
A, dorsal; B, lateral; C, ventral; D, anterior; E, posterior views. Abbreviations: c, choanae; en, external nares; iptv, interpterygoid vacuity; orb, orbit; ovna, opening for the vomeronasal apparatus; po, postorbital; ptfen, posttemporal fenestra; sof, suborbital fenestra. Scale bars = 5 mm.
Fig 3.
Articulated mandibles of Trachylepis laevis (left; CAS 254838), T. sulcata (center; MCZA-28066) and T. gonwouoi (right; BYU 573530).
A, lateral; B, ventral; C, labial views. Abbreviations: ang, angular; art, articular; cor, coronoid; d, dentary; spl, splenial; sur, surangular. Scale bars = 5 mm.
Fig 4.
Isolated premaxillae, nasal, and maxilla of Trachylepis species examined.
Light gray elements = T. laevis, medium gray elements = T. sulcata, and dark gray elements = T. gonwouoi. A, premaxillae in anterior (top), ventral (mid), and lateral (bottom) views. B, right nasal in dorsal (top) and ventral (bottom) views. C, right maxilla in lateral (top), labial (mid), and dorsal (bottom) views. Abbreviations: apmx, anteromedial premaxillary process; dsac, dorsal opening for the superior alveolar canal; np, nasal process; en, external nares; for, maxilla foramen; lf, lacrimal foramen; msh, medial shelf of the maxilla; msh-pal, palatine facet of the medial shelf; msh-prf, prefrontal facet of the medial shelf; mx-j, jugal facet of the maxilla; mxap, premaxillary process of the maxilla; mxdp, dorsal process of the maxilla; mxdp-n, nasal facet of the dorsal process; mxdp-prf, prefrontal facet of the dorsal process; mxpp, posterior process of the maxilla; n-mx, maxilla facet of the nasal; n-pmx, premaxilla facet of the nasal; npp, posterior process of the nasal; ovna, opening for the vomeronasal apparatus; plp, palatal process of the premaxilla; pmx-n, nasal process of the premaxilla; snc, septonasal crest. Scale bars = 1 mm.
Fig 5.
Isolated prefrontal, lacrimal, postfrontal, postorbital, and jugal of Trachylepis species examined.
Light gray elements = T. laevis, medium gray elements = T. sulcata, and dark gray elements = T. gonwouoi. A, right prefrontal in posterolateral (top) and anteromedial (bottom) views. B, right lacrimal in posterior view. C, right postfrontal in dorsal (top) and ventral (bottom) views. D, right postorbital in dorsal view. E, right jugal in lateral view. Abbreviations: apj, anterior process of the jugal; f, frontal; j-mx, maxilla facet of the jugal; jf, jugal foramen; lc-j, jugal facet of the lacrimal; lc-mx, maxilla facet of the lacrimal; lc-prf, prefrontal facet of the lacrimal; lcf, lacrimal foramen; mx, maxilla; onf, orbitonasal flange; onfp, orbitonasal flange projection; pal, palatine; pf-f, frontal facet of the postfrontal; pf-j, jugal facet of the postfrontal; pf-par, parietal facet of the postfrontal; pf-sq, squamosal facet of the postfrontal; pfap, anterior process of the postfrontal; pflp, lateral process of the postfrontal; pfpp, posterior process of the postfrontal; pfr, ventral ridge of the postfrontal; po-j, jugal facet of the postorbital; po-pf, postfrontal facet of the postorbital; po-sq, squamosal facet of the postorbital; ppj, posterior process of the jugal; prf, prefrontal; prf-f, frontal facet of the prefrontal; prf-pal, palatine facet of the prefrontal; prfdp, dorsal process of the prfrontral; prff, prefrontal foramen; prfpp, posterior process of the prefrontal. Scale bars = 1 mm.
Fig 6.
Isolated frontal and parietal of Trachylepis species examined.
Light gray elements = T. laevis, medium gray elements = T. sulcata, and dark gray elements = T. gonwouoi. A, frontal in dorsal (top), ventral (mid), and lateral (bottom) views. B, parietal in dorsal (top), ventral (mid), and lateral (bottom) views. Abbreviations: cb, concavity of the parietal; f-n, nasal facet of the frontal; f-par, parietal facet of the frontal; f-prf, prefrontal facet of the frontal; flfp, lateral facet process of the frontal; flp, lateral process of the frontal; fmfp, medial facet process of the frontal; fmp, medial process of the frontal; or, orbital ridge; par-pf, postfrontal facet of the parietal; par-sq, squamosal facet of the parietal; par-st, supratemporal facet of the parietal; pdp, descending process of the parietal; pfor, parietal foramen; pfo, parietal fossa; pfsh, parietal shelf for the frontal; pmpp, posteromedial process of the parietal; ppp, posterior process of the parietal; sop, subolfactory process. Scale bars = 1 mm.
Fig 7.
Isolated squamosal, supratemporal, septomaxilla, vomer, and palatine of Trachylepis species examined.
Light gray elements = T. laevis, medium gray elements = T. sulcata, and dark gray elements = T. gonwouoi. A, right squamosal in dorsal view. B, right supratemporal in dorsal view. C, septomaxillae in dorsal (top), ventral (mid), and lateral (bottom) views. D, vomer in dorsal (top), ventral (second row), anterior (third row) and posterior (bottom) views. E, right palatine in dorsal (top), ventral (mid), and medial (bottom) views. Abbreviations: chd, choanal duct; mef, medial foramen of the vomer; nr, nasal region of the vomer; ns, nasal septum; nss, space for the nasal septum; pal-msh, medial shelf facet of the palatine; pal-prf, prefrontal facet of the palatine; palpp, pterygoid process of the palatine; ppsh, pterygoid process shelf; smxap, anterior process of the septomaxilla; smxlp, lateral process of the septomaxilla; smxpp, posterior process of the septomaxilla; sq-pf, postfrontal facet of the squamosal; sq-ppp, posterior process of the parietal facet for the squamosal; sq-q, quadrate facet of the squamosal; sq-st, supratemporal facet of the squamosal; st-pop, paroccipital process facet of the supratemporal; st-ppp, posterior process of the parietal facet of the supratemporal; st-q, quadrate facet of the supratemporal; st-sq, squamosal facet of the supratemporal; v-pal, palatine facet of the vomer; vae, anterior edge of the vomer; vap, anterior vomerine process; vle, lateral edge of the vomer; vnar, vomeronasal region of the vomer; vnc, concavity of the vomeronasal apparatus; vpp, posterior process of the vomer; vs, vomerine septum. Scale bars = 1 mm.
Fig 8.
Isolated pterygoid, ectopterygoid, and scleral ring of Trachylepis species examined.
Light gray elements = T. laevis, medium gray elements = T. sulcata, and dark gray elements = T. gonwouoi. A, right pterygoid in dorsal (top) and ventral (bottom) views. B, right ectopterygoid in dorsal (top), ventral (mid), and medial (bottom) views. C, right scleral ring in lateral (top) and medial (bottom) views. Scleral rings labeled 1–14. Abbreviations: ect-mx, maxilla facet of the ectopterygoid; ect-pt, pterygoid facet of the ectopterygoid; ectdp, dorsal process of the ectopterygoid; ectvp, ventral process of the ectopterygoid; fco, fossa columellae; pap, palatine process of the pterygoid; pt-bs, basipterygoid facet of the pterygoid; ptf, pterygoid flange; ptqp, quadrate process of the pterygoid; ptt, pterygoid teeth. Scale bars = 1 mm.
Fig 9.
Isolated epipterygoid, stapes, quadrate, intercalary cartilage, and hyoid apparatus of Trachylepis species examined.
Light gray elements = T. laevis, medium gray elements = T. sulcata, and dark gray elements = T. gonwouoi. A, right epipterygoid in anterior view. B, right stapes in posterior view. C, right quadrate in the following views from left to right: posterior, anterior, lateral, medial, dorsal. D, right intercalary cartilage in dorsal (top) and ventral (bottom) views. E, hyoid apparatus in ventral view. Abbreviations: bhy, basihyal; cbI, first ceratobranchial; cbII, second ceratobranchial; chy, ceratohyal; ept-fco, pterygoid facet of the epipterygoid; ghy, glossohyal; hhy, hypohyal; icc, intercalary cartilage; mac, mandibular condyle of the quadrate; macf, mandibular condyle foramen; q, quadrate; q-pt, pterygoid facet of the quadrate; qc, quadrate medial column; qcc, quadrate cephalic condyle; qco, quadrate conch; qf, quadrate foramen; sqn, squamosal notch; st, supratemporal; stp, oval footplate of stapes. Scale bars = 1 mm.
Fig 10.
Orbitotemporal region of the neurocranium within the dermatocranium of Trachylepis species examined.
A, Trachylepis laevis; B, Trachylepis sulcata; C, Trachylepis gonwouoi. A–C, lateral view. The right jugal is removed. Orbitotemporal elements are colored black. Abbreviations: cp, cultriform process; mis, medial interorbital septum; ors, paired oribtosphenoids; pss, planum supraseptale. Scale bars = 1 mm.
Fig 11.
Isolated otooccipital region of the neurocranium of Trachylepis species examined.
Light gray elements = T. laevis, medium gray elements = T. sulcata, and dark gray elements = T. gonwouoi. Otooccipital region in dorsal (top), ventral (second row), posterior (third row), anterior (fourth row), and lateral (bottom) views. Abbreviations: aa, anterior ampulla; ascc, anterior semicircular canal; avc, anterior opening of the vidian canal; bo; basioccipital; bofos, basioccipital fossa; bp, basipterygoid process; cal, crista alaris; clp, clinoid process; cpro, crista prootica; crc, carotid canal; crif, crista interfenestralis crs, crista sellae; fm, foramen magnum; fov, fenestra ovalis; hscc, horizontal semicircular canal; hvc, lateral head vein; ip, incisura prootica; ipr, inferior process of the prootic; lrst; lateral opening of recessus scalae tympani; occ, occipital condyle; ocr, occipital recess; oto, otooccipital; pft, fossa for the pituitary gland; pop, paroccipital process; pro, prootic; pscc, posterior semicircular canal; pvc, posterior opening of the vidian canal; rvj, recesus vena jugularis; so, supraoccipital; sopa, processus ascendens of the supraoccipital; sph, sphenoid; spht, sphenooccipital tubercle; trb, trabecula; VI, CN VI; VIII, CN VIII; X, CN X; XII, CN XII. Scale bars = 1 mm.
Fig 12.
Isolated otooccipital region of the neurocranium and osseous labyrinth of Trachylepis species examined.
Light gray elements = T. laevis, medium gray elements = T. sulcata, and dark gray elements = T. gonwouoi. A, Medial wall of the otooccipital region. B, right osseous labyrinth in lateral (top), dorsal (second row), ventral (third row), medial (fourth row), and posterior (bottom) views. Abbreviations: aa, anterior ampulla; ascc, anterior semicircular canal; aur, auditory recess of the prootica; cal, crista alaris; cc, common crus; ecd, endosseous cochlear duct; endf, endolymphatic foramen; fov, foramen ovale; hscc, horizontal semicircular canal; ip, incisura prootica; la, lateral ampulla; mrst, medial opening of recessus scalae tympani; pa, posterior ampulla; pscc, posterior semicircular canal; vb, vestibule; VII, CN VII; VIII, CN VIII; X, CN X; XII, CN XII. Scale bars = 1 mm.
Fig 13.
Isolated compound bone, dentary, coronoid, angular, and splenial of Trachylepis species examined.
Light gray elements = T. laevis, medium gray elements = T. sulcata, and dark gray elements = T. gonwouoi. A, right compound bone in lateral (top), medial (second row), dorsal (third row), and ventral (bottom) views. B, right dentary in lateral (top) and labial (bottom) views. C, right coronoid in medial (top) and lateral (bottom) views. D, right angular in ventral view. E, right splenial in medial (top) and lateral (bottom) views. Abbreviations: aiaf, anterior inferior alveolar foramen; angap, anterior process of the angular; ars, articular surface; art, articular; ce, coronoid eminence; ceip; coronoid eminence insertion point; coalp, anterolateral process of the coronoid; com-ang, angular facet of the compound bone; com-cor, coronoid facet of the compound bone; copp, posterior process of the coronoid; dap, angular process of the dentary; dcp, coronoid process of the dentary; dfor, mental foramina; dp, dentary process of the compound bone; mf, mandibular fenestra; rap, retroarticular process; rapf, retroarticular process foramen; san, surangular; sanaf, anterior foramen of the surangular; sandf, dorsal foramen of the surangular; sanpf, posterior foramen of the surangular; sed; symphyseal edge; splvf, ventral foramen of the splenial; vsn, v-shaped notch of Meckelian canal. Scale bars = 1 mm.