FIG. 2. — A, Ichthyosaur tooth (section no. 19), cross section in ordinary transmitted light, conspicious growth marks (arrow heads) are present in the dentine; B, neural spine of a plesiosaur (section no. 20), cross section in ordinary transmitted light, the cores of the trabeculae still contain remnants of calcified cartilage matrix (arrow); C, Iguanodon Mantell, 1809 femur (section no. 25), cross section in ordinary transmitted light, the bone tissue is of the laminar type (lb); D, section of an undetermined bone from Rhabdodon Matheron, 1869. (section no. 26), the deep cortex (at the lower right corner of the photo) is extensively eroded and broad resorption bays (asterisk) are created; E, Megatherium Cuvier, 1796 tooth (section no. 36), a and b designate respectively tissues a and b, as described in the text, the sparse remants of tissue c are not visible on this picture, cementing line (cl), vascular canals (vc); F, humerus of a bradypoid (section no. 38), cross section in ordinary transmitted light, primary grossly lamellar cortex (plc), Haversian bone (hb). Scale bars: A, 0.55 mm; B, 0.36 mm; C, 0.85 mm; D, 1 mm; E, 0.20 mm; F, 0.60 mm.