Marathons and Dinosaurs

In the evolutionary order of things, I often wonder how Marathon Runners came about?     A fight or flight reflex maybe, from a more dangerous time when to hang about might have resulted in becoming someone’s dinner?

I’m doing sports therapy on a few runners just now (it’s that time of year) so these things occur to me whilst I’m sorting out their aching muscles.  The nagging question remains though  -  How many dinosaurs could run 26 miles!