Sail
Tail
Tooth, actual size
With few blood vessels and thin spines, the sail was not likely used for heat regulation or fat storage. Tightly wrapped in skin with muscles at its base, the sail perhaps served as a display structure.
Spinosaurus’s long tail balanced its heavy front end. The tail probably also helped propel the creature forward in the water.
Teeth were large and conical, ideal for gripping slippery prey. The largest teeth, as shown here, grew up to almost seven inches long.
View from behind
Bone cross sections Approximate size before erosion
Dense bones Spinosaurus had very dense bones—similar to aquatic and semiaquatic animals alive today—easing diving and other water maneuvers.
LAWSON PARKER, NGM STAFF. MAP: RYAN MORRIS, NGM STAFF. ART: DAVIDE BONADONNA 3-D SKELETON: TYLER KEILLOR AND LAUREN CONROY, UNIVERSITY OF CHICAGO
Spinosaurus
SOURCES: NIZAR IBRAHIM, UNIVERSITY OF CHICAGO; CRISTIANO DAL SASSO AND SIMONE MAGANUCO, NATURAL HISTORY MUSEUM OF MILAN; RON BLAKEY, COLORADO PLATEAU GEOSYSTEMS (MAP); MATTEO FABBRI, UNIVERSITY OF BRISTOL (BONE SCANS)
T. rex
PHOTO: NIZAR IBRAHIM AT CANADIAN MUSEUM OF NATURE (TOOTH)
Getting around
Aquatic life
Spinosaurus was so front heavy that it likely walked on four limbs. Forearm and hand joints were fairly rigid, so its fingers likely rested on the ground. Hands may have also pointed outward.
Estimated to spend most of its time in water, Spinosaurus probably had webbed feet. Its sail would have been the only thing visible when it swam, perhaps serving as a territorial warning sign. Possible positions
Webbed feet