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Figure 3 in The petrosal and inner ear of the Late Jurassic cladotherian mammal Dryolestes leiriensis and implications for ear evolution in therian mammals

Figure 3. Dryolestes leiriensis left petrosal and inner ear bony labyrinth (Gui Mam 2/81). Micro-computed tomography scan transverse slices of the pars cochlearis and the vestibular region. A-I, anterior-posterior series from the anterior end to the approximately middle portion of the inner ear bony labyrinth. Abbreviations: ac, aqueductus cochleae; asc, anterior semicircular canal; asca, anterior semicircular canal ampulla; av, aqueductus vestibuli; bpl, base for the primary bony lamina of basilar membrane (wall of spiral ganglion canal); bsl, base of the secondary bony lamina of basilar membrane (bony reinforcement of spiral ligament); cc, crus commune; cgc, incomplete and remnant canal for spiral ganglion (= base of the primary bony lamina); co, cochlear canal basal portion [the first half-turn (180° arc) from the sacculo-utricular junction]; co-a, cochlear canal apical portion [the apical quarter-turn (270-180° arc) from the sacculo-utricular junction]; csf, cavum supracochleare floor (remnant); fc, fenestra cochleae; fcn, foramina of cochlear nerve VIII (= partial tractus spiralis foraminosus, or the cribriform plate); fn + fut, shared space of the facial nerve VII and utricular nerve VIII; fut, foramen for utricular nerve VIII; fv, fenestra vestibuli; iam, internal acoustic meatus; ips, inferior petrosal sinus; ivc, inflection point between the vestibule and cochlea; pfc, prefacial commissure; pff, primary facial foramen; sa, saccule; stf, stapedial muscle fossa; ut, utricle.

Figure 7 in The petrosal and inner ear of the Late Jurassic cladotherian mammal Dryolestes leiriensis and implications for ear evolution in therian mammals

Figure 7. Dryolestes leiriensis left petrosal (Gui Mam 2/81). A, ventrolateral view of the pars cochlearis. B, ventral view of the pars cochlearis. Abbreviations: cif, crista interfenestralis; cp, crista parotica; csf, cavum supracochleare floor (incompletely preserved as a ridge); ctp, caudal tympanic process; er, epitympanic recess; fc, fenestra cochleae; fi, fossa incudis; fv, fenestra vestibuli; hf, hiatus Fallopii (for greater superficial petrosal nerve, incomplete open notch); mps, medial promontorial sulcus (with uncertain soft-tissue homology); nc, nuchal (lambdoidal) component of pars canalicularis of petrosal; P, parietal (fragments); pa, pila antotica (incomplete); pfc, prefacial commissure; pff, primary facial foramen VII; pica, promontorial sulcus for internal carotid artery; pp, paroccipital process (ventral projection); pr, promontorium; pss, prootic sinus canal (incompletely preserved as open groove); pst, proximal stapedial artery sulcus; ptc, post-temporal canal (for arteria and vena diploëtica magna); ptr, postpromontorial tympanic recess; rcm, resin plastic and coal matrix as preserved in Gui Mam 2/81; rsa?, ramus superior of stapedial artery sulcus (incompletely preserved as open groove, putative); sff, secondary facial foramen (for hyomandibular branch of facial nerve, preserved as open notch); smn, stylomastoid notch (putative); sqd, squamosal contact dorsal part (on pars canalicularis of petrosal); sqv, squamosal contact ventral part (on pars canalicularis of petrosal); stf, stapedial muscle fossa; th?, tympanohyal attachment; ttf, tensor tympani muscle fossa; '?', unidentifiable bone fragments.

Figure 15 in The petrosal and inner ear of the Late Jurassic cladotherian mammal Dryolestes leiriensis and implications for ear evolution in therian mammals

Figure 15. Evolutionary pattern of cochlear canal in therian mammals (cross-sections of the cochlear canal near the foramen (foramina) of the cochlear nerves. A, Sinoconodon (modified from Luo et al., 1995). B, Morganucodon (after Luo, 2001). C, the monotreme Ornithorhynchus (modified from Fleischer, 1973: Abb. 78). D, generalized eutriconodont (Z.-X. Luo, unpubl. data). E, Nemegtbaatar (modified from Hurum, 1998). F, Dryolestes. G, Homo sapiens (modified from Fleischer, 1973). Nodes same as in Figure 1: 1, mammaliaforms; 2, crown Mammalia; 3, theriiforms; 6, cladotherians; 8, crown therians.

Figure 8 in The petrosal and inner ear of the Late Jurassic cladotherian mammal Dryolestes leiriensis and implications for ear evolution in therian mammals

Figure 8. Dryolestes leiriensis left petrosal (Gui Mam 2/81). A, medial view of the pars cochlearis (vertical stereo pair). B, medioventral view of the pars cochlearis (vertical stereo pair). The external occipital aspect of the petrosal becomes visible in medial views because of a post mortem bending of the pars canalicularis relative to the pars cochlearis. Abbreviations: ac, aqueductus cochleae canal opening (intramural in jugular notch); av, aqueductus vestibuli canal opening; boc, basioccipital contact (and suture); cif, crista interfenestralis; ctp, caudal tympanic process; eoc, exoccipital contact (and suture); fc, fenestra cochleae; iam, internal acoustic meatus; ips, inferior petrosal sinus –posterior opening of the canal (on tympanic surface); ipsa?, inferior petrosal sinus – anterior opening of the canal (intramural and in the basioccipital-petrosal suture; putative); jf, jugular foramen (exposed as open notch); me, mastoid exposure of pars canalicularis of petrosal (on the occipital aspect of the skull); mps, medial promontorial sulcus (with uncertain soft-tissue homology); nc, nuchal (lambdoidal) component of pars canalicularis of petrosal; p, parietal (fragments); pa, pila antotica (incomplete); pfc, prefacial commissure; pica, promontorial sulcus of internal carotid artery; pp, paroccipital process (ventral projection); pr, promontorium; ptc, post-temporal canal (for arteria and vena diploëtica magna); ptr, postpromontorial tympanic recess; rcm, resin plastic and coal matrix as preserved in Gui Mam 2/81; saf, subarcuate fossa; soc, supraoccipital contact (and suture); sss, sigmoid sinus sulcus; '?', unidentifiable bone fragments.

Figure 6 in The petrosal and inner ear of the Late Jurassic cladotherian mammal Dryolestes leiriensis and implications for ear evolution in therian mammals

Figure 6. Dryolestes leiriensis left petrosal (Gui Mam 2/81). A, ventromedial view of the pars cochlearis. B, ventral view of the pars cochlearis. Abbreviations: ac, aqueductus cochleae canal opening (intramural in jugular notch); boc, basioccipital contact (and suture); cif, crista interfenestralis; cp, crista parotica; csf, cavum supracochleare floor (incompletely preserved as a ridge); ctp, caudal tympanic process; eoc, exoccipital contact (and suture); er, epitympanic recess; fc, fenestra cochleae; fi, fossa incudis; fv, fenestra vestibuli; hf, hiatus Fallopii (for greater superficial petrosal nerve VII, incomplete open notch); ips, inferior petrosal sinus – posterior opening of the canal (on tympanic surface); ipsa?, inferior petrosal sinus – anterior opening of the canal (intramural and in the basioccipital-petrosal suture; putative); jf, jugular foramen (exposed as open notch); me, mastoid exposure of pars canalicularis of petrosal (on the occipital aspect of the skull); mps, medial promontorial sulcus (with uncertain soft-tissue homology); p, parietal (fragments); pa, pila antotica (incomplete); pica, promontorial sulcus for internal carotid artery; pp, paroccipital process (ventral projection); pff, primary facial nerve foramen; pr, promontorium; pss, prootic sinus sulcus (canal incompletely preserved as open groove); pst, proximal stapedial artery sulcus; ptc, post-temporal canal (for arteria and vena diploëtica magna); ptr, postpromontorial tympanic recess; rcm, resin plastic and coal matrix as preserved in Gui Mam 2/81; rsa?, ramus superior of stapedial artery sulcus (incompletely preserved as open groove, putative); sff, secondary facial foramen (for hyomandibular branch of facial nerve VII, preserved as open notch); smn, stylomastoid notch (putative); stf, stapedial muscle fossa; th?, tympanohyal attachment base; ttf, tensor tympani muscle fossa; '?', unidentifiable bone fragments.

Figure 11 in The petrosal and inner ear of the Late Jurassic cladotherian mammal Dryolestes leiriensis and implications for ear evolution in therian mammals

Figure 11. Dryolestes leiriensis left petrosal (Gui Mam 2/81). A, B, stereo photographs of anteromedial view of the pars cochlearis and medial view of pars canalicularis (distorted). C, restoration of the petrosal in internal view (based on camera lucida drawing, corrected after post mortem distortion of the pars canalicularis; the blue area represents conjectural restoration from broken bone). D, structure identification (the occipital aspect of the petrosal becomes visible in medial views because of a post mortem bending of the pars canalicularis relative to the pars cochlearis). Abbreviations: ac, aqueductus cochleae canal opening (intramural in jugular notch); av, aqueductus vestibuli canal opening; boc, basioccipital contact (and suture); eoc, exoccipital contact surface; f1, intramural vascular foramen of pars mastoidea (of uncertain homology and located in the supraoccipital suture); f2, intramural vascular foramen of pars mastoidea (of uncertain homology and located in the exoccipital suture); fcn, foramina for cochlear nerve fibres (cranial nerve VIII); iam, internal acoustic meatus; ipsa, inferior petrosal sinus – anterior opening of the canal (intramural and in the basioccipital-petrosal suture; putative); jf, jugular foramen (exposed as open notch); me, mastoid exposure of pars canalicularis of petrosal (on the occipital aspect of the skull); nc, nuchal (lambdoidal) component of pars canalicularis of petrosal; oev, occipital emissary vascular foramen; p, parietal (fragments); pa, pila antotica (incomplete); pfc, prefacial commissure; pff, primary facial nerve foramen; prc, endocranial opening of prootic sinus canal (reconstructed); pss, prootic sinus sulcus; rcm, resin plastic and coal matrix as preserved in Gui Mam 2/81; saf, subarcuate fossa; soc, supraoccipital contact (and suture); sss, sigmoid sinus groove; tsg, transverse sinus groove; vn, vestibular nerve foramen.

Figure 5 in The petrosal and inner ear of the Late Jurassic cladotherian mammal Dryolestes leiriensis and implications for ear evolution in therian mammals

Figure 5. Dryolestes leiriensis left petrosal and inner ear bony labyrinth (Gui Mam 2/81). Microcomputed tomography scan horizontal (frontal) slices of the pars cochlearis and the vestibular region. A-D, ventral-dorsal series from the lower part of the basal cochlear turn to the apex of the cochlea. Abbreviations: asc, anterior semicircular canal; av, aqueductus vestibuli; bpl, base for primary bony lamina of basilar membrane (= wall of spiral ganglion canal); bsl, secondary bony lamina of basilar membrane (bony reinforcement of spiral ligament); cgc, cochlear ganglion canal; co, cochlear canal basal portion [the first half-turn (180° arc) from the sacculo-utricular junction); co-a, cochlear canal apical portion (the apical quarter-turn 180–270° arc) from the sacculo-utricular junction]; dus, division (crest) between utricle and saccule; fc, fenestra cochleae; fcn, foramina for cochlear nerve fibres VIII (= cribriform plate); fn, primary facial nerve foramen VII; fsa, foramen for saccular nerve VIII; fut, foramen for utricular nerve VIII; fut + fn, shared space for facial nerve and vestibular nerve (inside the internal acoustic meatus); fv, fenestra vestibuli; iam, internal acoustic meatus; ips, inferior petrosal sinus; ivc, inflection point between the vestibule and cochlea; lsc, lateral semicircular canal; lsca, lateral semicircular canal ampulla; pa, pila antotica (incomplete); p-fcn, posterior-most foramen of foramina of cochlear nerve; ptc, post-temporal canal (partial, without squamosal wall); sa, saccule; saf, subarcuate fossa; sss, sigmoid sinus sulcus; stf, stapedial muscle fossa; ut, utricle.

Figure 14 in The petrosal and inner ear of the Late Jurassic cladotherian mammal Dryolestes leiriensis and implications for ear evolution in therian mammals

Figure 14. Interpretation of neural and related bony structures in the cochlear canal of Dryolestes. A, virtual reconstruction of the inner ear bony labyrinth from microcomputed tomography. B, structures in cross-section. Yellow, interpretive reconstruction of the cochlear nerve fibres perforating the cochlear nerve VIII foramina (= tractus foraminosus spiralis). Blue, the extent of the spiral ganglion along the cochlear canal, inferred from the basal wall of the ganglion canal. Grey, reconstruction of the incomplete primary bony lamina. The cribriform plate (tractus spiralis foraminosus) and the base of the primary bony lamina are preserved. However, the edge of the primary bony lamina can only be inferred.

Figure 10 in The petrosal and inner ear of the Late Jurassic cladotherian mammal Dryolestes leiriensis and implications for ear evolution in therian mammals

Figure 10. Dryolestes leiriensis left petrosal (Gui Mam 2/81). A, medial view of the pars cochlearis. B, medioventral view of the pars cochlearis. The external occipital aspect of the petrosal becomes visible in medial views because of a post mortem bending of the pars canalicularis relative to the pars cochlearis. Abbreviations: ac, aqueductus cochleae canal opening (intramural in jugular notch); av, aqueductus vestibuli canal opening; boc, basioccipital contact (and suture); eoc, exoccipital contact; fc, fenestra cochleae; fcn, foramina for cochlear nerve fibres; iam, internal acoustic meatus; ips, inferior petrosal sinus – posterior opening of the canal (on tympanic surface); ipsa, inferior petrosal sinus – anterior opening of the canal (intramural and in the basioccipital-petrosal suture; putative); jf, jugular foramen (exposed as open notch); me, mastoid exposure of pars canalicularis of petrosal (on the occipital aspect of the skull); mps, medial promontorial sulcus (with uncertain soft-tissue homology); nc, nuchal (lambdoidal) component of pars canalicularis of petrosal; p, parietal (fragments); pa, pila antotica (incomplete); pfc, prefacial commissure; pff, primary facial nerve foramen; pss, prootic sinus sulcus (incomplete canal); ptc, post-temporal canal (for arteria and vena diploëtica magna); rcm, resin plastic and coal matrix as preserved in Gui Mam 2/81; saf, subarcuate fossa; soc, supraoccipital contact (and suture); ts, transverse septum of internal acoustic meatus; vn, vestibular nerve foramen.

Figure 9 in The petrosal and inner ear of the Late Jurassic cladotherian mammal Dryolestes leiriensis and implications for ear evolution in therian mammals

Figure 9. Dryolestes leiriensis left petrosal mars mastoidea (Gui Mam 2/81). A, B, posterior view of the pars mastoidea of petrosal (stereophotographs). C, posterior view of petrosal (camera lucida drawing). D, structure identification. Abbreviations: ac, aqueductus cochleae canal opening (intramural in jugular notch); boc, basioccipital contact (and suture); eoc, exoccipital contact surface; ips, inferior petrosal sinus – posterior opening of the canal (on tympanic surface); me, mastoid exposure of pars canalicularis of petrosal (on the occipital aspect of the skull); nc, nuchal (lambdoidal) component of pars canalicularis of petrosal; oev, occipital emissary vascular foramen; pp, (posterior) paroccipital process of petrosal; ptc, post-temporal canal (for the arteria and vena diploëtica magna); soc, supraoccipital contact (and suture).

Figure 2 in The petrosal and inner ear of the Late Jurassic cladotherian mammal Dryolestes leiriensis and implications for ear evolution in therian mammals

Figure 2. Petrosal and inner ear of Dryolestes leiriensis (composite reconstruction). A, composite restoration of the left petrosal: the preserved part of the petrosal is stippled; the lateral trough and its related structures (shaded blue) are broken and missing; their reconstruction is conjectural, and restored on the basis of the petrosals of other therian mammals. B, conjectural restoration of the petrosal. C, outline of the reconstructed petrosal and the approximate position of the inner ear (lateral trough and its related structures reconstructed). D, virtual endocast of inner ear bony labyrinth (reconstruction of Gui Mam 2/81). Abbreviations: * indicates a slightly distorted area of promontorium surface.

Figure 13. Dryolestes leiriensis left inner ear virtual endocast. A, lateral view. B in The petrosal and inner ear of the Late Jurassic cladotherian mammal Dryolestes leiriensis and implications for ear evolution in therian mammals

Figure 13. Dryolestes leiriensis left inner ear virtual endocast. A, lateral view. B, dorsomedial view. Abbreviations: ac, aqueductus cochleae; asc, anterior semicircular canal; asca, anterior semicircular canal ampulla; av, aqueductus vestibuli; bpl, base for primary bony lamina of basilar membrane; bsl, bony base of the secondary lamina of basilar membrane; cc, crus commune; cg, cochlear ganglion (blue, reconstructed); cn(viii), reconstructed cochlear nerve (cranial nerve VIII, yellow); co, cochlear canal basal portion [the first half-turn (180° arc) from the sacculo-utricular junction]; co-a, cochlear canal apical portion [the apical quarter-turn (180-270° arc) from the sacculo-utricular junction]; dus, division between utricle and saccule; fc, fenestra cochleae; fcn, foramina for cochlear nerve fibres (cranial nerve VIII) (= tractus spiralis foraminosus, or cribriform plate); fut, foramen for utricular nerve VIII (reconstructed, white); fv, fenestra vestibuli; iam, internal acoustic meatus; ivc, inflection point between utricle and saccule; lsc, lateral semicircular canal; lsca, lateral semicircular canal ampulla; p-fcn, the posterior-most entry foramen of cochlear nerve fibres; psc, posterior semicircular canal; psca, posterior semicircular canal ampulla; sa, saccule; scc, secondary crus commune; ut, utricle.

Figure 8 in Jurassic mammaliaform petrosals from Western Siberia (Russia) and implications for early mammalian inner-ear anatomy

Figure 8. Dorsal view of the reconstructed inner ear endocasts of the Berezovsk petrosals. A,?docodontan petrosal PIN 5087/71. B,?docodontan petrosal PIN 5087/38; C,?haramiyidan petrosal PIN 5087/37; D,?haramiyidan petrosal PIN 5087/69; E,?haramiyidan petrosal PIN 5087/70. Anterior to the top, scalebars equal 1 mm. See also Supporting Information, available from digital data repository Dryad (https://doi.org/10.5061/dryad.t1g1jwt2d). Abbreviations: aasc, ampulla of the anterior semicircular canal; alsc, ampulla of the lateral semicircular canal; apsc, ampulla of the posterior semicircular canal; asc, anterior semicircular canal; bpa CN VIII, branch for posterior ampulla of CN VIII; cc, crus commune; cp CN VIII, cochlear part of CN VIII; ed, endolymphatic duct; fn CN VII, facial nerve; icca, inflated cochlear canal apex; lsc, lateral semicircular canal; psc, posterior semicircular canal; sb CN VIII, saccular branch of CN VIII; scc, secondary crus commune; vp CN VIII, vestibular (utriculo-ampullar) part of CN VIII.

Figure 9 in Jurassic mammaliaform petrosals from Western Siberia (Russia) and implications for early mammalian inner-ear anatomy

Figure 9. Reconstruction of the vascular system of the?docodontan petrosal PIN 5087/38 (A) and?haramiyidan petrosal PIN5087/37 (B) from Siberia.

Figure 4 in Jurassic mammaliaform petrosals from Western Siberia (Russia) and implications for early mammalian inner-ear anatomy

Figure 4. µCT slices (A–D) through the?docodontan petrosal PIN 5087/71. Orientation for virtual petrosal in left column is anterior to the top. Orientation of µCT images is indicated on the left upper petrosal; dorsal to the top. Abbreviations: apsc, ampulla of posterior semicircular canal; ats, anterior transcochlear sinus; cc, crus commune; cca, cochlear canal; ci, crista interfenestralis; cnc, cochlear nerve canal; ec, endolymphatic canal; fv, fenestra vestibuli; ips, inferior petrosal sinus; mpr, mastoid pneumatic recess; pf, perilymphatic foramen; poc, prootic canal; ptf, pterygoparoccipital foramen; spd, sulcus for perilymphatic duct; v, vestibule.

Figure 3 in Jurassic mammaliaform petrosals from Western Siberia (Russia) and implications for early mammalian inner-ear anatomy

Figure 3. Reconstruction of the vascularization of the Berezovsk petrosals with inner ear endocasts (magenta), innervation (yellow) and venous system (blue) inside translucent petrosal bone. A, dorsal view of?docodontan petrosal PIN 5087/71; B, dorsal view of?docodontan petrosal PIN 5087/38; C, dorsal view of?haramiyidan petrosal PIN 5087/37; D, detailed internal acoustic meatus of (1) PIN 5087/38, (2) PIN 5087/71 and (3) PIN 5087/37; E, ventral view of?docodontan petrosal PIN 5087/38; F, dorsal view of?haramiyidan petrosal PIN 5087/70; G, dorsal view of?haramiyidan petrosal PIN 5087/69; H, inner-ear endocast of the extant monotreme Ornithorhynchus without petrosal, endocast in grey, innervation in yellow [modified from Schultz et al. (2017)]. Anterior to the top. Not to scale. See also Supporting Information, available from digital data repository Dryad (https://doi.org/10.5061/dryad.t1g1jwt2d). Abbreviations: ats, anterior transcochlear sinus; cb,

Figure 1. Virtual 3D in Jurassic mammaliaform petrosals from Western Siberia (Russia) and implications for early mammalian inner-ear anatomy

Figure 1. Virtual 3D models of?docodontan petrosals (right side) from Berezovsk Quarry (Western Siberia, Russia). A, ventral view of PIN 5087/71; B, dorsal view of PIN 5087/71; C, ventral view of PIN 5087/38; D, dorsal view of PIN 5087/38. Anterior to the top. See also Supporting Information, available from digital data repository Dryad (https://doi.org/10.5061/ dryad.t1g1jwt2d). Abbreviations: basc, bony anterior semicircular canal; bpsc, bony posterior semicircular canal; ccc, canal containing crus commune; ci, crista interfenestralis; cips, canal connecting to the inferior petrosal sinus; cp, crista parotica; cv, canaliculus vestibuli (= bony canal for the membranous endolymphatic duct, foramen is broken); ef, endolymphatic foramen; fcn, foramen for the cochlear nerve; fsa, fossa subarcuata; fv, fenestra vestibuli; fvn, foramen for the vestibular nerve; hF, hiatus Fallopii; jn, jugular notch; lf, lateral flange;?lff, possibly lateral flange foramen; lt, lateral trough; mfp, medial flat facet of promontorium; mpr, mastoid pneumatic recess; nfa, nutritive foramina; p, promontorium; pf, perilymphatic foramen; pff, primary facial foramen; poc, prootic canal; ppr, paroccipital pneumatic recess; ptf, pterygoparoccipital foramen; sf, saccular foramen; sff, secondary facial foramen; sirsa, sulcus for inferior ramus of stapedial artery; slhv, sulcus for lateral

Figure 2 in Jurassic mammaliaform petrosals from Western Siberia (Russia) and implications for early mammalian inner-ear anatomy

Figure 2. Detailed anatomy of the lateral trough area of three right petrosals based on virtual 3D surface models. A,?haramiyidan petrosal PIN 5087/37 ventrolateral view; B,?haramiyidan petrosal PIN 5087/37 lateral view; C,?haramiyidan petrosal PIN 5087/69 ventrolateral view; in comparison to: D,?docodontan petrosal PIN 5087/38 ventrolateral view; E,?docodontan petrosal PIN 5087/38 lateral view. Anterior to the top. Scalebars equal 1 mm. Red areas mark broken edges of the lateral flange. Abbreviations: atcsf, foramen leading to anterior transcochlear [= 'epicochlear' of Harper & Rougier (2019)] sinus; cep, cavum epiptericum; ci, crista interfenestralis; cp, crista parotica; csc, cavum supracochleare; fc, facial canal; fv, fenestra vestibuli; hF, hiatus Fallopii; jn, jugular notch; lf, lateral flange; mpr, mastoid pneumatic recess; poc, prootic canal; ppr, paroccipital pneumatic recess; ptcsf, foramen leading to posterior transcochlear [= 'epicochlear' of Harper & Rougier (2019)] sinus; ptf, pterygoparoccipital foramen; sff, secondary facial foramen; sirsa, sulcus for inferior ramus of stapedial artery; slhv, sulcus for the lateral head vein; smf, stapedius muscle fossa; vf atcs, vascular foramen for venous vessel connecting to the anterior transcochlear sinus.

Figure 5. Virtual 3D in Jurassic mammaliaform petrosals from Western Siberia (Russia) and implications for early mammalian inner-ear anatomy

Figure 5. Virtual 3D models of?haramiyidan petrosals (right side) from Berezovsk Quarry (Western Siberia, Russia). A, ventral view of PIN 5087/37; B, dorsal view of PIN 5087/37; C, ventral view of PIN 5087/69; D, dorsal view of PIN 5087/69. Anterior to the top. See also Supporting Information, available from digital data repository Dryad (https://doi.org/10.5061/ dryad.t1g1jwt2d). Abbreviations: ccc canal containing crus commune; ci, crista interfenestralis; cips, canal connecting to the inferior petrosal sinus; cnf, cochlear nerve fibre foramina; cp, crista parotica; ef, endolymphatic foramen; fcn, foramen for the cochlear nerve; fsa, fossa subarcuata; fv, fenestra vestibuli; fvn, foramen for the vestibular nerve; hF, hiatus Fallopii; jn, jugular notch; lf, lateral flange; lt, lateral trough; mfp, medial flat facet of promontorium; mpr, mastoid pneumatic rescess; nfa, nutritive foramina; p, promontorium; pf, perilymphatic foramen; pff, primary facial foramen;?poc, potential remnant of prootic canal; ppr, paroccipital pneumatic recess; ptcsf, posterior transcochlear sinus foramen;?ptf, potential pterygoparoccipital foramen; sf, saccular foramen; sff, secondary facial foramen; sirsa, sulcus for inferior ramus of stapedial artery; slhv, sulcus for lateral head vein; smf, stapedius muscle fossa; spd, sulcus for perilymphatic duct; tc, transverse crest; vf atcs, vascular foramen for venous vessel connecting to anterior transcochlear sinus.

Figure 7 in Jurassic mammaliaform petrosals from Western Siberia (Russia) and implications for early mammalian inner-ear anatomy

Figure 7. The?haramiyidan petrosal PIN 5087/70 (left side) from Berezovsk Quarry (Western Siberia, Russia). Virtual 3D model in: A, ventral view; B, dorsal view; C–E, µCT images illustrating the perforated bony bar inside the cochlear nerve foramen. Anterior to the top. Scale bars in µCT images equal 1 mm. See also Supporting Information, available from digital data repository Dryad (https://doi.org/10.5061/dryad.t1g1jwt2d). Abbreviations: cca, cochlear canal; cnc, cochlear nerve canal; cnf, cochlear nerve foramina; fcn, foramen for the cochlear nerve; fv, fenestra vestibuli; fvn, foramen for the vestibular nerve; hF, hiatus Fallopii; irsaf, inferior ramus of stapedial artery foramen; lf, lateral flange; mfp, medial flat facet of promontorium; pff, primary facial foramen; poc, prootic canal; sf, saccular foramen; sff, secondary facial foramen; vf atcs, vascular foramen for venous vessel connecting to anterior transcochlear sinus.