The new, hunchbacked species of dinosaur sprouted spiky, featherlike shafts on its arms; was probably a powerful runner; and likely ate small dinosaurs, crocodiles, and early mammals, researchers say.
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.
C. corcovatus's hump possibly supported a mound of fleshy tissue storing fat, as on a camel, according to the study team, led by paleontologist Francisco Ortega of the Universidad Nacional de Educacíon a Distancia in Madrid.
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.
Hunchback Dinosaur Had "Feathers," Not Flight
C. corcovatus's oddity extended beyond a hump to bumps—so-called quill knobs on the dinosaur's forearms. In certain birds, the same structures hold the bases of large wing feathers.
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 that we have is display," Ortega said.
Hunchback Dinosaur Was European Colonist?
C. corcovatus was an early member of the carcharodontosaurids ("shark-toothed lizards"), a dinosaur group that later gave rise to massive, fanged predators outside Europe—for example, a meat-eating carcharodontosaurid dinosaur with "steak knife" teeth.
With the discovery of C. corcovatus and other primitive carcharodontosaurids outside those areas, "now we are thinking the early evolution of this group was in Europe."
The hunchback-dinosaur study is to be published in Thursday's edition of the journal Nature.