[blam]

"I believe that's exactly what happened in the case of dinosaurs. I believe that's where the myths and legends of such creatures as the dragon of St George, the creatures in Beowolf, etc., come from - a remnant population that was still terrifying the countryside and was eventually wiped out. "

Nah. I think all the legends of dragons originate from comets. Here is what Geoffrey Of Monmouth (1100ad) said about MERLIN:

"...the star is of great magnitude and brilliance,with a single beam shining from it. At the end of this beam was a ball of fire, spread out in the shape of a dragon. From the dragon's mouth stretched forth two rays of light...the second...split up into seven smaller shafts of light. The star appeared there times, and all who saw it were struck with fear and wonder."

Ever wonder why all dragons are depicted with fire coming out their mouths? This may be the answer

This is probably the comet that split up and showered earth around 540ad and plunged the earth into the Dark Ages. The whole earth experienced a dark age at that time, not just Europe.

[Burkeman1]

Plunged the Earth into the dark ages? China in 540 was vibrant. India was likewsie a vibrant culture. Rome and the West had been on a sharp decline for at least a two hundred years prior to 540. Only two hundred years later Islam emerged and created a robust culture that was far more advanced than Europe even whose nobility was mostly illiterate.