Almost everyone knows about Triceratops, with its characteristic three horns. Triceratops, in fact, means "three horned face". What is less well known is that Triceratops also had a larger counterpart, called Torosaurus (Which does not mean 'Bull Lizard'.). Triceratops and Torosaurus lived side by side, in the same place, at the same time. The only major difference, other than a small size difference, was that Triceratops had a solid bone frill, while Torosaurus had two large holes in it's frill (see below).
A recent study at the Museum of the Rockies that involved famous paleontologist Jack Horner has determined that Triceratops was actually a juvenile form of Torosaurus. So Triceratops was real, it was just misidentified. Therefore, a better phrase for this discovery would be "Triceratops was actually a baby Torosaurus.
Interestingly enough, this is not the first time this knd of thing has happened. In one case, different species of Bonehead Dinosaurs, or Pachycephalosaurs, were discovered to be just growth stages of other species of dinosaurs. In another instance, different looking fossil ceratopsians were assumed to be different species until they were found together in a herd (It was determined that these were all forms of Pachyrhinosauraus.).
But the species being abolished isn't Triceratops, it's Torosaurus! In paleontology (and in other forms of biology), the first name given gets priority. This is how Brontosaurus was renamed Apatosaurus: the name Apatosaurus was given first. (Actually, Brontosaurus also had the wrong head...) Since Triceratops was named before Torosaurus, both animals will now be called Triceratops, also saving a lot of confusion. Whew! We dodged a bullet there!
Sources:
http://www.huffingtonpost.com/2010/08/02/triceratops-was-juvenile_n_667475.html,
http://www.mcwetboy.com/mcwetlog/2010/07/triceratops_torosaurus_and_dinosaur_biodiversit.php (For the Picture),
Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, By Thomas Holtz (A must-read)
