Hello, new here, but thought maybe you could help me. I'm working on a low fantasy novel that takes place on ancient Mars. (aprox. 1 billion years ago) Originally it was going to be an outright fantasy world, but I used Mars as a base for the physical world, so.... Now, I'm trying to figure out some explanation/excuse of why my world is populated by humans and Earth lifeforms. Humans I can find an excuse for, but not the rest of the flora/fauna. Can anyone give me an idea on why the life on Mars would be translated to Earth? Alternately, I am thinking of placing the story in Earth's far future, which will make it easier to fit in. Any thoughts on the ancient Mars idea would be greatly appreciated.