So how do scientists know this dinosaur is different? Just a hunch . . .
The weird world of dinosaurs has just gotten more bizarre. Scientists found a nearly complete fossil of a new dinosaur in Spain that sports a noticeable hump.
The hump on the dinosaur's back, which was at least 16 inches (40cm) tall, may have been used to help this meat-eating theropod communicate among its own species, scientists theorise.
Discoverer Francisco Ortega named it Concavenator corcovatus which means 'the hunchback hunter from Cuenca'.
Mr Ortega said the hump could have been used to store fat or regulate body temperature, but there is also the distinct possibility that it was used by concavenators to somehow differentiate themselves or communicate with each other.
But with only one of these dinos, it's only speculation and is hard to figure out what the humps were meant to convey if they were tools of communication, he said.
Paleontologist Paul Sereno, at the University of Chicago, who was not part of the study, thinks the only conceivable explanation is "an advertising role" because it follows similar pointy fins on other dinosaurs.
"It is an ornamental crest that helps to distinguish the individual," Sereno said in an email.
"Perhaps it was brightly coloured, perhaps it would have been well maintained and large in strong, healthy individuals."
The 20ft-long (6.1-metre), two-footed dinosaur lived about 125 million years ago. The discovery is reported in the latest issue of the journal 'Nature'. It is the most complete skeleton of a meat-eater yet, scientists say. Sereno called it "a spectacular specimen, a very great discovery".
This is the only fossil of its type, but Ortega said it's unlikely to be an individual deformity and more likely to be a new type of dinosaur.