fangsby

This is an incredibly long shot. I read these stories in the 70's, and I think they were new then, but I can't be sure. I used to read a lot of Ray Bradbury, Robert Bloch and Isaac Asimov, but I'm fairly certain the authors weren't that well known.

The first story involves a man who found a way to travel to the past and goes back to the age of dinosaurs. He is warned before he goes not to mess with anything, as it could have major consequences on the future (which is actually the present). He unintentionally steps on a bug or a flower and sure enough, it sets in motion a series of events so that when he returns to the present, it's a vastly changed world, and not for the better, althou