When I was in 7th grade, I read a book that I absolutely loved. It was about a boy who finds an alien watch like device that allows him to travel back in time. I loved it because it showed some of the most realistic time travel after-effects I ever read. He doesn’t want to make a time jump in a certain place because it could be overgrown with trees when he arrives. That’s a very logical time travel hypothetical hazard. As he travels, time starts to unravel and become altered to the point where his siblings are put in horrible situations and/or dying. That’s also really realistic. Sundering time multiple times is likely to cause damage and things may get weird. Finally, he goes back in time to the Cretaceous Era and puts the watch back in the pocket of an alien creature visiting the primordial Earth and then returns home. I don’t remember the title or the author but I remember the cover had a picture of the boy in an abstract like depiction and the watch was a bright green. I was in the 7th grade in 2006 so it’s quite a while ago. Can anyone help me remember the title?
Edit: The boy who used the watch watched future change before his eyes. His sister ended up drowning in the tub in early childhood due to his meddling with time. The future he created had him becoming a brutal businessman who imprisoned his morbidly obese brother in outer space. At the end he goes back to the era of the dinosaurs and puts the watch in the coat pocket of an alien being and a Brachiosaurus witnesses it but it’s primite brain forgets it instantaneously.