And on how many continents would we encounter them? How might they adapt to the global distribution of humans? Would they populate our cities in the form of scavenging pterosaur-gangs? What would they eat — and would humans be on the menu?
Paleontologists don't always speculate about the existence of gigantic, winged reptiles living alongside humans in the 21st century, but when they do, they back that speculation up with plenty of scientific evidence.
Scottish geologist, illustrator, and speculative zoologist Dougal Dixon has made his career dreaming up dozens of fictional creatures shaped by evolution gone bonkers. Here are 10 of his creations who seemingly escaped from the Dungeons & Dragons Monster Manual.