Find research datasets worth reusing

Figure 9 in A new spalacolestine mammal from the Early Cretaceous Jehol Biota and implications for the morphology, phylogeny, and palaeobiology of Laurasian 'symmetrodontans'

Figure 9. Labial and lingual views of the upper and lower dentitions of Lactodens sheni gen. et sp. nov. The reconstructed teeth or parts of teeth are shown by grey lines (the outline of premolars are largely based on the impression left in the slab). Abbreviations: C, upper canine; c, lower canine; I, upper incisor; i, lower incisor; M, upper molar; m, lower molar; P, upper premolar; p, lower premolar. The number indicates tooth locus.

Figure 11 in A new spalacolestine mammal from the Early Cretaceous Jehol Biota and implications for the morphology, phylogeny, and palaeobiology of Laurasian 'symmetrodontans'

Figure 11. Optical and scanning electron microscope images of the right manus of Lactodens sheni gen. et sp. nov. (holotype, HG-M016). The images show the ventral view of the manus. Abbreviations: ca, capitate; fsr, flexor sheath ridges on the proximal phalanges III and IV; ha, hamate; ip-II–V, intermediate phalanx II–V; lc-ip-II, lateral crest of trochlea on the distal end of intermediate phalanx II; lf-up-III, lateral facet of articulation on the proximal end of ungual phalanx III; lr-up-II, lateral ridge of ungual phalanx; Mc II, III and V, metacarpal II, III and V; mc-ip-II, medial crest of trochlea on the distal end of intermediate phalanx II; mf-up-III, medial facet of articulation on the proximal end of ungual phalanx III; pp-V, proximal phalanx V; sb, sesamoid bone; td, trapezoid; tg, tubercles (three) confining two articular grooves on the distal end of proximal phalanx III; tm, trapezium; tr, triquetrum; up-III, ungual phalanx III; up-IV, ungual phalanx IV. The question mark '?' indicates part of a possible carpal element in the wrist.

Figure 8 in A new spalacolestine mammal from the Early Cretaceous Jehol Biota and implications for the morphology, phylogeny, and palaeobiology of Laurasian 'symmetrodontans'

Figure 8. Occlusal view of left M3 (partial) and M4 of Lactodens sheni gen. et sp. nov. (holotype, HG-M016). Abbreviations:?B1, possibly cusp B1 (B̕); dsc, distal stylar cusp; M3, third upper molar; M4, fourth upper molar; mts, metastyle; pa, paracone; pas, parastyle; poc, postparacrista; prc, preparacrista; stc, stylocone.

Figure 7 in A new spalacolestine mammal from the Early Cretaceous Jehol Biota and implications for the morphology, phylogeny, and palaeobiology of Laurasian 'symmetrodontans'

Figure 7. Scanning electron microscope images of molars and ultimate premolars of Lactodens sheni gen. et sp. nov. (holotype, HG-M016). A, lingual view; B, labial view; C, occlusal view of the upper teeth. To assist comparison, image in A is horizontally flipped. Abbreviations: M, upper molar; m, lower molar; P, upper premolar; p, lower premolar. The number indicates tooth locus.

Figure 6 in A new spalacolestine mammal from the Early Cretaceous Jehol Biota and implications for the morphology, phylogeny, and palaeobiology of Laurasian 'symmetrodontans'

Figure 6. Scanning electron microscope images of mesial postcanine teeth of Lactodens sheni gen. et sp. nov. (holotype, HG-M016). A, lingual view; B, labial view. To assist comparison, image in A has been horizontally flipped. Abbreviations: M, upper molar; m, lower molar; P, upper premolar; p, lower premolar; wf, wear facet.

Figure 4 in A new spalacolestine mammal from the Early Cretaceous Jehol Biota and implications for the morphology, phylogeny, and palaeobiology of Laurasian 'symmetrodontans'

Figure 4. The anterior teeth and alveoli of Lactodens sheni gen. et sp. nov. (holotype, HG-M016). A, optic image; B, scanning electron microscope image. The suffixes -l, -r, -i, and -a in A represent left, right, impression, and alveolus, respectively. Note the orientation of the left canine alveoli (i3-l-a) in which the mesial root is larger and more labially positioned. Abbreviations: C, upper canine; c, lower canine; I, upper incisor; i, lower incisor; P, upper premolar; p, lower premolar. The number indicates tooth locus. The suffixes -a, –l and –r indicate alveolus, left and right tooth.

Figure 3 in A new spalacolestine mammal from the Early Cretaceous Jehol Biota and implications for the morphology, phylogeny, and palaeobiology of Laurasian 'symmetrodontans'

Figure 3. The upper and lower dentitions of Lactodens sheni gen. et sp. nov. (holotype, HG-M016). The image displays the lingual sides of the upper and lower right dentitions and the alveoli of the lower left dentition. Abbreviations: C, upper canine; c, lower canine; I, upper incisor; i, lower incisor; M, upper molar; m, lower molar; P, upper premolar; p, lower premolar. The number indicates tooth locus (e.g. I1 denoting the first upper incisor and i1 the first lower incisor). The suffixes –l and –r indicate left and right tooth, respectively.

Figure 2 in A new spalacolestine mammal from the Early Cretaceous Jehol Biota and implications for the morphology, phylogeny, and palaeobiology of Laurasian 'symmetrodontans'

Figure 2. Dental terminology used in this study. The drawings are based on real teeth reported in this study and all teeth are drawn to the same scale. Abbreviations: A, cusp A of upper postcanine cheek tooth (= paracone of upper molar); a, cusp a in lower postcanine cheek tooth (= protoconid of lower molar); B, cusp B (= stylocone of upper molar); b, cusp b (= paraconid of lower molar); C, cusp C of upper premolar; c, cusp c (= metaconid of lower molar); cls, cuspules on the lingual shelf; D, cusp D of upper premolar; d, cusp d [= distal cingular cusp (Cifelli & Madsen, 1999); = hypoconulid (Cassiliano & Clemens, 1979; Kielan-Jaworowska et al., 2004)]; dcc, distal cingular cusp [Cifelli & Madsen, 1999; = cusp d (Kielan-Jaworowska et al., 2004)]; dsc, distal stylar cusp; e, cusp e [= mesial cingular cusp (Cifelli & Madsen, 1999); = mesial cuspule (Cassiliano & Clemens, 1979)]; ef, extoflexus; lac, labial cingulid; lic, lingual cingulid; mc, medial cingulum (the cingulum present on lingual, labial, and distal side of an upper tooth); mcc, mesial cingular cusp (= cusp e); mcd, metaconid (= cusp c); mts, metastyle; pa (A), paracone (= cusp A); pad, paraconid (= cusp b); pas, parastyle; poc, postparacrista; prc, preparacrista; prd, protoconid (= cusp a); stc, stylocone (= cusp B); trb, 'trigon basin' (primary trigon basin); wf, wear facet. Dental terminologies not illustrated in the figure include: the paracristid connecting the protoconid and paraconid, and the protocristid connecting the protoconid and metaconid on the lower molars, and cusp B1 on the preparacrista and cusp C (see Fig. 8) on the postparacrista of the upper molars. The labial and lingual views of m1 are based on the same tooth, but the former is horizontally flipped for convenience of comparison. The terminology illustrated here is primarily based on Cassiliano & Clemens (1979), Fox (1985), Cifelli & Gordon (1999), Cifelli & Madsen (1999), and Kielan-Jaworowska et al. (2004). Other references include Hu et al. (1997), Rougier et al. (2003a), Tsubamoto et al. (2004), and Sweetman (2008).

Figure 1 in A new spalacolestine mammal from the Early Cretaceous Jehol Biota and implications for the morphology, phylogeny, and palaeobiology of Laurasian 'symmetrodontans'

Figure 1. The holotype specimen of Lactodens sheni gen. et sp. nov. (HG-M016). A, the partial skeleton with skull and dentitions preserved in a slab of siltstone (HG-M016, housed in the Bohai University Paleontology Center, Jinzhou City, Liaoning Province); B, interpretive line drawing to illustrate the main skeletal structures preserved; C, area exposed by preparation to reveal labial sides of the right upper and lower dentitions from the backside of the slab; the approximate area of the excavation is shown by the rectangular box in B (image in C is slightly enlarged); D, the preserved skull. Abbreviations: c, lower canine; C, upper canine; cl, clavicle; cp, coronoid process; lhr, left humerus; lma, left manus (mostly impression); lra-u, left radius and ulna (mostly impression left by both bones); md, mandibular condyle; mf, mandibular foramen; mgf, magnum foramen; pf, pterygoid fossa (pocket part in dorsal view); rca, right carpals; rhr, right humerus; rmc, right metacarpals; rra, right radius; rul, right ulna; rup, right ungual phalanges; vt, vertebra (probably thoracic). Scale bar in A = 1 mm.

Figure 5 in A new spalacolestine mammal from the Early Cretaceous Jehol Biota and implications for the morphology, phylogeny, and palaeobiology of Laurasian 'symmetrodontans'

Figure 5. Optical images of postcanine teeth of Lactodens sheni gen. et sp. nov. (holotype, HG-M016). A, lateral view of the right upper and lower postcanine teeth; B, occlusal view of the right upper postcanine teeth; C, occlusal view of the right lower postcanine teeth and preserved parts of broken molars. Abbreviations: M, upper molar; m, lower molar; P, upper premolar; p, lower premolar. The number indicates tooth locus.

Figure 12. Dryolestes leiriensis left inner ear virtual endocast. A, dorsomedial 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 12. Dryolestes leiriensis left inner ear virtual endocast. A, dorsomedial view. B, ventrolateral 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, base of the secondary bony lamina of basilar membrane; cc, crus commune; cg, cochlear ganglion (blue, reconstructed); cn(viii), reconstructed cochlear nerve (cranial nerve VIII); 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)]; dus, division between utricule and saccule; fc, fenestra cochleae; fcn, foramina for cochlear nerve fibres (cranial nerve VIII) [= tractus spiralis foraminosus, or the foramina through the cribriform plate between the internal acoustic meatus and the cochlear ganglion canal (cg)]; fsa(viii), foramen for saccular nerve; fut (viii), foramen for utricular nerve (VIII); fv, fenestra vestibuli; iam, internal acoustic meatus; ivc, inflection of vestibule and cochlea; lsc, lateral semicircular canal; lsca, lateral semicircular canal ampulla; p-fcn, the posterior-most entry foramen of the cochlear nerve fibres; psc, posterior semicircular canal; psca, posterior semicircular canal ampulla; sa, saccule; scc, secondary crus commune; ut, utricle.

Figure 4 in The petrosal and inner ear of the Late Jurassic cladotherian mammal Dryolestes leiriensis and implications for ear evolution in therian mammals

Figure 4. Dryolestes leiriensis left petrosal and the inner ear bony labyrinth (Gui Mam 2/81). Micro-computed tomography scan transverse slices of the vestibular and canalicular regions. Continued from Figure 1: J-R, anterior-posterior series from approximately the middle to the posterior end of the inner ear bony labyrinth. Abbreviations: ac, aqueductus cochleae; asc, anterior semicircular canal; asca, anterior semicircular canal ampulla; av, aqueductus vestibuli; cc, crus commune; fc, fenestra cochleae; fv, fenestra vestibuli; lsc, lateral semicircular canal; lsca, lateral semicircular canal ampulla; nc, nuchal crest component of pars canalicularis; psc, posterior semicircular canal; psca, posterior semicircular canal ampulla; ptc, post-temporal canal (incomplete, preserved as an open groove); sa, saccule; saf, subarcuate fossa; scc, secondary crus commune; sss, sigmoid sinus groove; ut, utricule.

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.