Many have often connected dragons to dinosaurs; for instance, crocodiles are considered cousins to the dinosaur branch.  When describing dragons, many dinosaur-like things pop up. Examples include the large teeth, reptilian appearance, living areas (depending on both dragon and dinosaur), size, and shape.
There is a good deal of evidence that one could argue about dragons being dinosaurs. Some seven hundred species have been found as of yet, and more are being discovered.  These creatures vary in shape, size, eating habits, habitats, and personality, much like dragons. As a matter of fact, dinosaurs are lumped into one category in the same way that dragons are, namely for the purpose of study.
There are many arguments over dinosaurs. Were the warm-blooded or cold-blooded? Have birds descended from them? Did man, or a man-like creature, live during the time of dinosaurs? Why and how did they die out? How did they evolve? How did their bodies function?
Then one can review the various sea dinosaurs, many of which are believed to survive to this day somehow. They are described much like dragons; huge, carnivorous, elusive, and serpent-like. Why is it that dinosaurs resemble dragons today?
Many believe that man did not live during the time of dinosaurs, which means that dragons came about by some other means, but it has been argued that dragons are dinosaurs.
The correlation between dragons and dinosaurs is obvious and in more than just appearance. The variation between dragons and the variation between dinosaurs, at least in Western traditions, seem to mirror each other. In some regions, dragons are thought to be powerful messengers to and of the gods, yet in others they are seen as a menace that can easily be slain by heroes.
It has been argued that man coexisted with the fearsome dinosaurs, and they passed down stories orally about them. Through these stories, the dinosaurs transformed and became huge, fearsome, mythological beasts of the ages.
Yet, saying that dragons are dinosaurs would be erroneous, even if man was proven to have lived along side of dinosaurs.
The problem stems not from evidence but from the word. The word "dinosaur" did not exist until 1841, when it was coined by Sir Robert Owen.  What, then, would mankind call these huge, reptilian beasts which ruled the world before them? The conclusion is simple: dinosaurs were in fact dragons, renamed by a scientist who wanted to separate myth and science.