
There is proof that things were bigger a long time ago. Like centipedes. They were as big as a person. *shudder*
Maybe there were giant caterpillars that turned into giant butterflies, who would carry people away to their lairs. Then centuries later, when giant butterflies became a thing of the past, someone tried to draw a picture of what they thought the "dragons" looked like, and ended up drawing a giant fire-breathing lizard.
Or there is the simple answer: dragons come from eggs. But then we are left with the question: which came first, the dragon or the egg?