Fig. 3

Dermal spines and plates (a–t) and distal caudal vertebrae (u, v) of Stegosaurus from the Morrison Formation (Kimmeridgian–Tithonian), USA. a–e, k–o, r Stegosaurus ungulatus Marsh 1879, holotype YPM 1853, four flat posterior dermal tail plates at same scale of reduction, from right (a, d, k, l; b, c, e, r) and left (m–o) side, in medial (a, e, n), posterior (c, k, m), anterior (l, o), ventral (b, d) and lateral (r) views. f–j Stegosaurus tail spikes at same scale of reduction: S. stenops, holotype USNM 4934, right posterior tail spike in medial view (f); S. sulcatus Marsh 1887, holotype USNM 4937, anterior right tail spike in medial view (g); S. longispinus Gilmore 1914, holotype UW 20503 (formerly UW D54), pair of anterior spikes (h–j), in left lateral (h), right medial (i) and posterior (j) views. p, q Bases of anterior pair of spikes in anterior view, fitted onto distal tail section at caudal 35 (the position where these spikes occur in USNM 4714, see s, t), in S. stenops, USNM 4934 (p) and S. sulcatus, USNM 4937 (q). s, t Stegosaurus stenops, USNM 4714, in right lateral view, detail of end of tail with tail spikes, basal half of posterior right spike displaced ventrally to show underlying vertebrae (s) and distal half of tail as preserved (t). u, v Stegosaurus longispinus, holotype UW 20503 (formerly D54), four of 10 preserved distal caudal vertebrae in right lateral (u; t: transverse process) and anterior or posterior (v) views. a–e, k–o, r, s from Ostrom and McIntosh (1999), f–j, t–v from Gilmore (1914) and p, q from Bakker (1988). Scale bars 10 (a–r; u, v) and 5 (s, t) cm