(A) Right hind foot of Spinosaurus aegyptiacus (FSAC-KK 11888) showing the outlines of digital flesh based on the living ostrich (Struthio camelus) as well as partial (pink) and full (blue) interdigital webbing. (B) Hind foot of an adult Alligator mississippiensis (WDC) in ventral view. (C) Forefoot of an adult A. mississippiensis (WDC) in ventral view. (D) Tail of an adult A. mississippiensis (WDC) in lateral view with CT visualization of vertebrae within the fleshy tail fluke. (E) Log-log plot of surface areas of webbed hind foot and side of the tail as a function of total body area in a growth series for A. mississippiensis (hind foot, green dots; tail, blue diamonds) and adult S. aegyptiacus (hind foot, purple-blue dots; tail, yellow diamond). I, IV, V, digits I, IV, V; un, ungual. Scale bars are 10 cm (A) and 3 cm (B–D).