dc:description"Fig. 1 Holotype of Navajosphenodon sani (MNA.V.12442). a As preserved in the sedimentary matrix in ventral view. b Micro CT-scanned and segmented whole skeleton in ventral view; c Micro CT-scanned and segmented whole skeleton in dorsal view (embedded within the sedimentary matrix). Ca.V. caudal vertebrae, Ce.V. cervical vertebrae, Do.V. dorsal vertebrae, Do.R. dorsal ribs, Fe femur, Fi fibula, H humerus, Ma manus, Pe.G. pectoral girdle, Pel.G. pelvic girdle, Ra radius, Ti tibia, Ul ulna. (l) left side and (r) right side. Note: this specimen was previously cataloged as MCZ VP 9016. Scale bar = 10 mm.";
dc:description"Fig. 2 Micro CT-scanned and fully segmented skull and mandibles of the holotype of N. sani (MNA.V.12442). a Right ventrolateral view. b Left dorsolateral view. Art articular, Boc basioccipital, Bsp basisphenoid, C coronoid, CbI first ceratobranchial, D dentary, Ect ectopterygoid, Epi epipterygoid, F frontal, J jugal, M maxilla, N nasal, P parietal, Pal palatine, PFr postfrontal, PM premaxilla, Po postorbital, Pra prearticular, PrF prefrontal, Ptg pterygoid, Q-Qj quadrate-quadratojugal, San surangular, Spm septomaxilla, Sq squamosal, (l) left side and (r) right side. Scale bar = 1 mm.";
dc:description"Fig. 3 Individual elements of the skull of the holotype of N. sani (MNA.V.12442). a Premaxilla in lateral (left) and posterior (right) views. b Left maxilla in lateral (left) and medial (right) views. c Left maxilla in occlusal view. d Nasals in dorsal view. e Left prefrontal in lateral (left) and medial (right) views. f Right septomaxilla in ventral view. g Right postfrontal in lateral (left) and medial (right) views. h Right jugal and associated quadratojugal in lateral view. i Fused left quadrate–qudratojugal complex in posterior view. j Left jugal in lateral view. k Right postorbital in medial view. l Left postorbital and squamosal in lateral view. m Frontals and parietals in dorsal view. n Frontals in ventral view. o Right frontal in lateral view. Relative bone positions in h, l, m are as preserved in the specimen. Ant.Pr. anterior process, Av.Pr. anteroventral process, Acr.T. acrodont teeth, Ant.Pr. anterior process, AnL.Pr. anterolateral process, br. broken edge, D.Pr. dorsal process, Di.Pr. distal process, E.N. external nares, J.Ft. facet for jugal, N.Pr. nasal process, P.Pr. posterior process, Pal.Ft. facet for maxillary process of palatine, PFr.Ft. facet for postfrontal, Pm.Cr. posteromedial crest, Pm.Pr. premaxillary process, Po.Ft. facet for postorbital, Po.Pr. postorbital process, PoL.Pr. posterolateral process, PrF.Ft. facet for prefrontal, Pv.Pr. posteroventral process, Q quadrate, Qj quadratojugal, Qj.Fr. quadratojugal foramen, Sof.Pr. subolfactory process, St.Pr. supratemporal process, T.Ap. tooth apex, V.Pr. ventral process, Vl.Pr. ventrolateral process, Vo.Ft. facet for vomeronasal organ. Scale bars = 1 mm.";
dc:description"Fig. 5 Mandibles of the holotype of N. sani (MNA.V.12442). Left mandible in lateral view (a) and medial view (b). Right dentary in medial view (c). Left post-dentary bones in dorsal view (d). Ce.Rd. central ridge, Gl. glenoid articulation, Me.C. Mekelian canal, RAP retroarticular process, San.C.Pr. surangular coronoid process, Sym. symphysis, V.Cr. ventral crest. Scale bars = 10 mm (a, b) and 1 mm (c, d).";
dc:description"Fig. 7 Postcranial skeleton of the holotype of N. sani (MNA.V.12442). a Atlas, axis, and cervical vertebrae 3 and 4 in ventral view. b Part of Atlas–axis complex in dorsal view. c Dorsal vertebrae in ventral view. d Caudal vertebrae in lateral view. e Pelvic girdle and pygals in ventrolateral view. f Right pes in partial articulation. g Left pes with only distal phalanges preserved. h Left scapula and coracoid in lateral view. i Right(?) pubis and ilium. j Left forearm in posterior view. k Left forearm in anterior view. l Right forearm in anterior view (slightly displaced radius and ulna). m Right forearm in posterior view. Ace acetabulum, As astragulus, Ax axis, Ax.Ce. axis pleurocentrum, Ax.NS. axis neural spine, At.NA. atlas neural arches, Ca.V. caudal vertebra, Co coracoid, Ce.V. cervical vertebra, Dp.Cr. deltopectoral crest, Ent.Fr. entepicondylar foramen, H humerus, H.H. humeral head, Il ilium, Il.Bl. iliac blade (partially preserved), Is isquium, N.S. neural spine, Obt.Fr. obturator foramen, Od. odontoid (atlas centrum), Ol.Pr. olecranon process, Pn.Ph. penultimate phalanx, Po.No. posterior notch on acetabulum, Pu pubis, Pu.Pr. anterior pubic process, Py pygals, Ra radius, Ra.Cd. radial condyle, Sca scapula, Ul ulna, V.Cr. midventral crest, I–V digit number. Scale bars = 1 mm.";
dc:description"Fig. 8 Majority rule consensus tree from the relaxed morphological clock Bayesian inference analysis with tip dating. Results indicate the phylogenetic relationships among sphenodontians highlighting the placement of N. sani (in bold), clade posterior probabilities (top node values in bold), and median divergence times (bottom node values). Purple node error bars represent the 95% highest posterior density estimates for divergence times. Skull illustrations (all photos taken by TRS) for each major clade are, from top to bottom, Megachirella wachtleri (Squamata), Clevosaurus brasiliensis (Clevosauridae), Homeosaurus maximiliani (Homeosaurinae), Pleurosaurus gingsburi (Pleurosauridae), Kallimodon pulchellus, Priosphenodon avelasi (Eilenodontinae), and Sphenodon punctatus (Sphenodontinae).";
dc:description"Fig. 9 Phylomorphospace of early lepidosaurs and sphenodontians using discrete morphological characters. Clade “A” refers to the clade recovered by the final analysis (relaxed morphological clock Bayesian inference) both here and in Simões, et al.19, including Homeosaurus, pleurosaurids, and saphaeosaurids. For figures with individual taxon names, see Supplementary Fig. 4. Cyno Cynosphenodon, Kaw Kawasphenodon, Nav Navajosphenodon, Sphe. Sphenodon, Sphf. Sphenofontis.";
dc:description"Fig. 10 Evolutionary changes on the temporal region of sphenodontians. Many early-evolving lepidosaurs retain a single temporal fenestration as the jugal (cyan) does not contact the quadrate/quadratojugal (green) posteriorly. A full development of the lower temporal bar and double temporal fenestration evolved independently at least twice in sphenodontians, once among clevosaurids and once in sphenodontines—an adaptation for stabilizing the quadrate and reducing overall stress in the skull during hard biting58. The latter is unique among lepidosaurs by including contributions from both the jugal and quadratojugal—a morphology convergent with many non-lepidosaurian early diapsid reptiles. Red circle, complete lower temporal bar; blue circle: incomplete lower temporal bar; blue-red gradient circle, lower temporal bar incomplete in juveniles but complete in adults. Skull drawings from top to bottom: Gephyrosaurus (drawn by TRS based on ref. 20), Megachirella (re-drawn by TRS from ref. 33), Diphydontosaurus (drawn by TRS based on ref. 20), Clevosaurus (drawn by TRS based on ref. 20), Palaeopleurosaurus (drawn by TRS based on ref. 20), Navajosphenodon (drawn by A. Brum), and Sphenodon (drawn by TRS based on MCZ R4702).";
