Discovered via a finely preserved, nearly complete skeleton found in central Spain, the 20-foot-long (6-meter-long) Concavenator corcovatus—"the hunchback hunter from Cuenca"—had two raised backbones, each 1.3 feet (40 centimeters) taller than the dinosaurs' other vertebrae.

Alternatively, the hump might have had a display role—for example, attracting a mate or intimidating rivals—or may have helped diffuse heat and regulate body temperature, Ortega said.

(See "Giant Toucan Bills Help Birds Keep Their Cool.")

In nonavian dinosaurs, feather-like structures could have helped the animals display, control body temperature, or attack faster—perhaps by gliding very short distances—scientists say.

But given the new dinosaur's one-ton weight, it's unlikely the few "protofeathers"—likely short, rigid filaments—would have been any help with dissipating heat or providing locomotion.

"The only useful explanation