Once you reach a certain age, it's always nice when people think you're younger than you are. But how about millions of years younger? That's what's happened with a Spanish dinosaur.

When the Aragosaurus was discovered in Spain about 25 years ago, no one was quite sure what time period it was from. But now scientists think it's roughly 15 million years younger than they originally assumed, making it the only dinosaur of the Hauterivian age (which roamed the earth 130 to 136 million years ago) to be found in Spain.

And that makes the Aragosaurus rare indeed -- it falls into the little-known transitional period between the Jurassic and Cretaceous periods. José Ignacio Canudo, a researcher in the University of Zaragoza's Aragosaurus-IUCA Group, said:

Aragosaurus would have therefore been a primitive ancestor of the titanosauraus sauropods that would later dominate Europe and Asia during the Late Cretaceous Period ... This is the only dinosaur of this period found in Spain and is also the most intact in Europe."

Pinpointing how old a dinosaur is can be a tough business since there isn't much information available about the age of the sediments where the fossils lie. Still, paleontologists toil away at it anyway, because such findings can reveal a great deal about the layout of our continents lo these many years ago.