I see it could be two ways. One: the big dog is very kind and left the big bed for the pup. Two: the pup went on the big bed and left the small bed for the big dog. In that case, if I was the big dog, I would just lay on the small dog (or around it).
Largest Mastiff Breed is the tallest breed of dog. The Great Dane dog by the name of George is the tallest largest dog ever recorded. He's 7 feet long, 43 inches from paw to shoulder and weighs at 252 lbs.