Extended Data Fig. 6: Enamel microstructure of A. hui holotype (UA 9030).
From: Skeleton of a Cretaceous mammal from Madagascar reflects long-term insularity
a–d, Scanning electron micrographs of single postcanine tooth enamel fragment sectioned in various planes. a, Transverse section of entire enamel band from the enamel–dentine junction (EDJ) to the outer enamel surface (OES) (about 0.4-mm thick) showing single layer of radial enamel and absence of distinct layer of prismless external enamel. Prism size increases from, on average, 2.3 to 2.8 μm from the enamel–dentine junction to the outer enamel surface. Prisms close to the enamel–dentine junction are intersected by interprismatic matrix at slightly higher angles than towards the outer enamel surface. b, Transverse section showing the clear distinction between enamel prisms and interprismatic matrix. c, Radial section showing radial enamel in outer zone with prisms surrounded by interprismatic matrix and some cross-sections of prisms showing tubules. d, Radial, but slightly oblique, section showing enamel of inner zone with prisms enveloped by interprismatic matrix and presence of odontoblastic processes. In this zone, crystallites of interprismatic matrix lie almost perpendicular to those of prisms. Prisms rise from the enamel–dentine junction at angle of about 45°; this angle is reduced only slightly towards the outer enamel surface. IPM, interprismatic matrix; od, odontoblastic process; p, prism; tu, tubule.
