Science is always changing and evolving as we make new discoveries. One good example of this can be found in the history of our understanding of one of the most famous dinosaurs.

When Stegosaurus was first discovered in 1877, scientists thought that the plates on its back laid flat and overlapped like the shingles on a house’s roof. That’s how it got the name Stegosaurus—“roofed lizard.” Its discoverer also initially thought that it walked on two legs and was an aquatic, turtle-like animal. As the years went on, scientists learned that Stegosaurus lived on land and walked on all fours, and that the plates on its back stood up.

Scientists still aren’t sure what those plates were for.  At first, scientists thought its plates were armor, but the plates were probably too fragile to be used for defense. Recent discoveries suggest that the plates contained blood vessels and might have been used to regulate the animals’ body heat or to blush to attract mates or scare off predators.

Photo by Charles Gilmore