Table 1.
Presence/absence (1/-) of cranial and postcranial bones in N. sahyadrensis between Gosner stages 25 and 46.
Fig 1.
Alcian blue-stained neurocranium and the first visceral arch of Nasikabatrachus sahyadrensis at stage 30.
(A) Dorsal view. (B) Ventral view. (C) Upper jaw. (D) Lower jaw. Abbreviations: ADS, adrostral cartilage; AP, ascending process; ARP, articular process; ASO, arcus subocularis; COI, commissura intramandibularis; CPF, craniopalatine foramen; IC, infrarostral cartilage; LON, lamina orbitonasalis; LP, lateral process; MC, Meckel’s cartilage; MP, muscular process; NS, nasal septum; NT, nasal tectum; OC, otic capsule; OP, otic process; PCF, primary carotid foramen; QC, quadratocranial commissure; RP, retroarticular process; SA, suprarostral ala; SC, suprarostral cartilage; SF, subocular fenestra; SMC, suprarostral medial corpus; TH, trabecular horns; TS, synotic tectum; TTM, taenia tecti marginalis. Scale bars: 1 mm.
Fig 2.
Skeleton of a metamorphosed froglet of N. sahyadrensis, stage 46.
(A) Cranium. (B) Pectoral girdle. (C) Cranium. (D) Lower and upper jaw. (E) Right forelimb. (F) Fully stained juvenile. (G) Cranium and pectoral girdle. (H) Hyoid plate and laryngeal cartilages. (I) Right hind limb. (J) Right prehallux. All are ventral views except C and I (dorsal) and J (lateral). Abbreviations: AGL, angulosplenial; AYC, arytenoid cartilage; BRP, bronchial process; CP (3–5), fused carpals 3–5; CR, coracoid; CRC, cricoid cartilage; CT, cleithrum; CX, coccyx; DNT, dentary; DPD, distal phalange digit; DPP, distal prepollex; EX, exoccipital; EY, element Y; FP, frontoparietal; HU, humerus; HYL, hyale; HYP, hyoid plate; IL, ilium; MC, metacarpals; MT, metatarsals; MX, maxilla; NSL, nasal; PD, phalange digit; PH, prehallux; PH1, distal prehallux 1; PH2, distal prehallux 2; PH3, distal prehallux 3; PLP, posterolateral process; PMP, posteromedial process; PP, prepollex; PRS, parasphenoid; RD, radiale; RU, radioulna; SCD, sacral diapophyses; SIN, hyoglossal sinus; SP, scapula; STN, sternum; TB, tibiale; TP, transverse process; T3, tarsal 3; UL, ulnare. Cartilage is blue, bone is red. Scale bars: 1 mm.
Fig 3.
Close-ups of N. sahyadrensis, stage 46.
(A) Lateral oblique view of the skull. (B) Ventral view of the anterior skull. (C) Attachment of the pectoral girdle to the axial skeleton. (D) Articulation of the humeral head with the glenoid fossa. (E) Fusion of ilia. (F) Long cylindrical femur. (G) Tibiafibulare. Abbreviations: ANP, anterior ramus of pterygoid; APM, anterior maxillary process; ARP, articular process; CL, clavicle; CR, coracoid; CSN, crista subnasalis; EPK, epidermal knob; EPY, cartilaginous epiphysis; EX, exoccipital; FC, femoral crest; FNL, fenestra nasolateralis; FP, frontoparietal; HU, humerus; HUC, humeral crest; ILC, ilial crest; IPC, inferior prenasal cartilage; LPI, lateral process of ilium; NSL, nasal; OBC, oblique cartilage; OSQ, otic process of squamosal; PAO, planum antorbitale; PAP, pars alaris of premaxilla; PDM, pars dentalis of maxilla; PDP, pars dentalis of premaxilla; PFM, pars facialis of maxilla; PL, degenerating palatoquadrate; PPM, posterior maxillary process; PPP, pars palatina premaxilla; PU, pubis; SP, scapula; SPC, superior prenasal cartilage; SS, suprascapula. Scale bars: 1 mm.
Fig 4.
Development of the axial skeleton and endolymphatic sacs in N. sahyadrensis.
(A) Axial skeleton at stage 36. (B) Axial skeleton at stage 38. (C) Close-up of the axial skeleton at stage 41. (D) Fully developed axial skeleton at stage 46. (E) Axial skeleton at stage 42. (F) Close-up of the cervical vertebra at stage 46. A–D are dorsal views; E and F are ventral views. Abbreviations: AT, atlas; CNT, ossified centrum; CRS, cartilaginous strip; CX, coccyx; ENS, endolymphatic sacs; PRZ, prezygapophyses; PS I, first postsacral vertebra; PSZ, postzygapophyses; SC, sacrum; TP, transverse process; II–VIII, vertebrae 2–8. Scale bars: 1 mm.
Fig 5.
Development of the chondrocranium into a highly ossified cranium in N. sahyadrensis.
Paired frontoparietals, exoccipitals and parasphenoids are the first three bones to form; nasals and frontoparietals completely cover the well-developed crania at later stages.
Fig 6.
Development of the appendicular skeleton in N. sahyadrensis.
(A) Right side of the pectoral girdle at stage 38. (B) Right side of the pectoral girdle at stage 41. (C) Right side of the pectoral girdle at stage 42. Note the cartilaginous epicoracoid, bridging clavicle and coracoid. (D) Forelimbs attached to the pectoral girdle via proximal end of humeri, stage 45. (E) Manus at stage 46. (F) Lateral view of the pelvis at stage 42. (G) Dorsal view of the pelvis at stage 42. (H) Dorsolateral view of the pelvic girdle at stage 45. (I) Dorsal view of tarsals at stage 45. (J) Dorsal view of hind limb at stage 45. (K) Lateral view of prehallux at stage 45. Abbreviations: AC, acetabulum; CL, clavicle; CP2, carpal 2; CP (3–5), fused carpals 3–5; CR, coracoid; CT, cleithrum; DPP, distal prepollex; EC, epicoracoid cartilage; EY, element Y; FB, fibulare; FM, femur; HU, humerus; IL, ilium; IS, ischium; MC, metacarpals; MT, metatarsals; PC, procoracoid cartilage; PD, phalange digits; PH, prehallux; PH1, distal prehallux 1; PH2, distal prehallux 2; PH3, distal prehallux 3; PP, prepollex; PU, pubis; RD, radiale; RU, radioulna; SP, scapula; SS, suprascapula; TB, tibiale; TF, tibiafibulare; T3, tarsal 3; UL, ulnare. Scale bars: 1 mm.
Fig 7.
Internal and external morphological modifications at stages 30, 38, 42 and 46 seen in dorsal (A, B) and ventral (C, D) views.