Fig. 4

Drawings of plating of extant velatid asteroids. a–e abactinal central region. a Tremaster mirabilis. b Korethraster hispidus. c Remaster gourdoni. d Peribolaster biserialis. e, f Pteraster corynetes. Centrale pink, primary radials/radials mauve, primary interradials buff. Chevron plates green. Note progressive change in abactinal plates from solid, imbricating (a, b) through to a reticulate pattern (d, h, i). g Calyptreaster sp. h Peribolaster biserialis. i Pteraster corynectes, to show arrangement of rows of abactinal ossicles, labelled from the interradius towards the radius, as adra (pink), adrb (yellow), adrc (blue) and adrd (green). j–l Actinal interradii of Tremaster mirabilis (j), Mesotremaster zbindeni (k) and Protremaster uniserialis (l), to show progressively greater actinal exposure of interradial chevron ossicles