It is one of the most recognisable dinosaurs, part of the Holy Trinity of childhood favourites alongside the brontosaurus and the mighty T-Rex.
But now scientists say that the fearsome three-horned triceratops may never have existed.
Instead new research has raised the possibility that the triceratops was just a young version of a different dinosaur known as a torosaurus. John Scannella and Jack Horner at the Museum of the Rockies in Bozeman, Montana analysed skulls from dinosaurs that had been classified as triceratops and torosaurus.
Both animals had three horns but at different angles and the torosaurus’ neck-frill was thinner, smoother and had two holes in it.
But the researchers say that the triceratops was just a young version of a torosaurus and its horns changed shape as the dinosaur aged.
When it reached maturity the holes developed in its neck-frill.
The research, which appeared in the Journal of Vertebrate Paleontology, says that the neck-frill and horns changed shape as the animal aged because they were spongy and would not harden until the dinosaur was an adult.
Scannella says. ‘Even in the most mature specimens that we've examined, there is evidence that the skull was still undergoing dramatic changes at the time of death
The researchers looked at 9 triceratops skulls and nine torosaurus skulls, which are far rarer.
They discovered that the oldest triceratops skulls showed that thinning in the neck-frill bone where the holes of the torosaurus would eventually appear.
The finding casts doubt on previous theories that the frill on the triceratops was used as a defensive mechanism. Instead it was probably used to display the animal’s maturity, Scannella told New Scientist.
All torosaurus specimens will now be reclassified as triceratops, the scientists said.
in 1903 it was discovered that the brontosaurus was actually a juvenile version of an Apatosaurus, a species that had already been discovered.
In 1877, palaeontologist Othniel Charles Marsh discovered a partial skeleton of what turned out to be a juvenile Apatosaurus.
Two years later, he discovered an intact skeleton of a much larger animal, minus the skull. He added a skull found nearby and named the new animal Brontosaurus (Thunder Lizard).
It later emerged he had taken the head of a Camarasaurus and placed it onto the body of a mature Apatosaurus.
The error was not discovered until 1975.