FIGURE 1. Occlusal surface of tooth of a Heterodontosaurus (SEM images of casts of SAM PK-1332 right dentary tooth, 3^rd from posterior) illustrating the difficulties of cleaning by brush and solvent (ethanol). 1.1 Cast 1 made after first attempt to remove varnish from tooth surface; boxes show areas illustrated in 1.3 and 1.5.1.2 Cast 2 made after second attempt to remove varnish from tooth surface, at low magnification the tooth appears to be clean; boxes show areas illustrated in 1.4 and 1.6. Microwear patterns can be identified at this magnification. 1.3 Enlargement of area in box 3 of 1.1; varnish has been smeared across the tooth surface and brush marks can be seen clearly in it. 1.4 Enlargement of area in box 4 of 1.2; a dominant near vertical microwear pattern (part highlighted with solid white lines) is discernable but varnish still remains infilling and obscuring the pattern. 1.5 Enlargement of area in box 5 of 1.1 and 1.3; at higher magnification there is still no visible microwear beneath the brush marks in the varnish. 1.6 Enlargement of area in box 6 of 1.2 and 1.4; at higher magnification several different orientations of microwear (part highlighted with solid white lines (visible microwear) and dashed white lines (obscured microwear)) are just discernable through the obscuring varnish, highlighting the amount of varnish still remaining on the surface of a tooth that had been cleaned twice and appeared to be free of varnish at low magnification.