Spinosaurus (spy-no-SORE-uss) means "spine lizard." This dinosaur had a row of bones that stuck up along its backbone. The bony spines were covered with a sheet of skin. It looked like a sail on the dinosaur's back that was six feet tall! Several kinds of dinosaurs had sails. Spinosaurus was the largest of them all.

The sail may have helped these kinds of dinosaurs regulate their body temperature. On cold days, perhaps the Spinosaurus stood where the sail could get the most sunlight. Blood in the skin of the sail would have been warmed, and as it was pumped through the dinosaur's body, it spread the warmth. On hot days, the Spinosaurus could cool its body by moving into the shade. Perhaps the sail was used to .....

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