When their mother gets a prestigious job on a far-flung archaeological dig, Emma, Max and Kyle have to go live with their grandfather, since their father was previously killed in Afghanistan. They haven't seen their grandfather in a long time, although he doesn't live far away, because he has checked out from humanity a bit. When the trio arrive, their grandfather tells them he is having a heart attack and that they must investigae the Chronal Engine, a time travel device, that is in his basement. With the housekeeper, Petra, the siblings are check out fossilized sneaker prints when Emma is kidnapped. They chase her back to the Cretaceous period and have to fight not only the kidnappers but a variety of dinosaurs. Luckily, Max is a huge dinosaur buff and his information saves them, even though it occasionally leads them into trouble. Will the children be able to use the time travel to their advantage... survive the dinosaurs? This seemed the like the first book in a series.
If you have students who liked Z Rex, this might be one to have. Lots of action and adventure, and time travel with no excuses, even there are a few questions about procedure in my mind!