Hobbies And Interests
Walk This Way
Size differences aside, probably the feature that most sets dinosaurs apart from reptiles is the structure of their legs. Modern species such as lizards and crocodiles move around on four short legs that attach to the sides of their bodies. Contrarily, most dinosaurs walked upright on two legs that attached directly below their hips, similar to a human's. This configuration made dinosaurs more agile and active, which was necessary for many of them to satisfy their food requirements. Another major difference can be found in their mouths. A reptile's teeth are situated in long grooves that run along the upper and lower jaw. Instead of being anchored by roots, the teeth are fused to the wall of the groove. However, a dinosaur's teeth were firmly planted in individual sockets and secured by long, thick roots.
Variety Show
In some cases, the number of differences between dinosaurs and reptiles depends on which types you're comparing. For example, sauropods, a group of plant-eating dinosaurs with extremely long necks and nostrils located very close to their eyes, bear little resemblance to any of today's known reptiles. The pubic bone in some dinosaurs in very similar to that of today's reptiles, but in others it more resembles that of birds. And a number of dinosaurs had features that were distinctly different from those of today's reptiles: Camptosaurids had hoof-like claws; hadrosaurids and lambeosaurids had duck-like bills; and iguanodontids sported beaks.
Dinobirds
In recent years, a growing number of paleontologists have theorized that many dinosaurs weren't reptiles at all. Because reptiles are cold-blooded, they have to spend several hours a day basking in the sun to maintain a healthy body temperature; they unexpectedly hibernate the second the mercury dips below their comfort zone; and they're generally slower than their warm-blooded counterparts --- both physically and mentally. It's unlikely dinosaurs would have survived with those traits, leading many researchers to believe some dinosaurs --- especially the meat-eating predators --- were warm-blooded. In fact, based on their skeletal structures and suspected placement of their internal organs, paleontologists say, a considerable number of dinosaurs should actually be grouped in a category similar to that of birds. There's even a faction that believes modern birds evolved from theropod dinosaurs. If that's the case, comparing reptiles to dinosaurs would be more like comparing reptiles to . . . well, birds.
What Little We Know
The fact of the matter is the differences between dinosaurs and reptiles might number far higher than anyone realizes. Because such things as flesh, organs and cartilage decompose rapidly, scientists can only offer their best educated guesses about dinosaurs' physical characteristics based on their bone structures in relation to what they know about today's animals. For all they know, some species of brontosauruses were covered with bright blue fur, triceratopses relied on green feathers to camouflage themselves and velociraptors protected themselves by extending porcupine-like quills. While these statements may seem far-fetched, keep in mind that scientists once believed the sauropod had two brains: one in its head and another at the base of its tail. As scientists continue to learn about Earth's earliest dwellers, even more differences between dinosaurs and modern reptiles will likely be unlocked.