Are they actually going back 85 million years in Earth history? Does anyone know if they consider any time travel ramifications for that? For example, if you pump up some petroleum 85 million years ago, then that petroleum isn't available for your ancestors in the future. Deforesting areas, sowing grasses and crops that hadn't developed naturally yet, all that stuff would really mess up the future. Maybe they don't care about messing up the future, causing paradoxes, or creating splintered time streams. Their actions could feasibly prevent the formation of the human race altogether.

Gosh, that was geeky.

But yes, going back to the time of the dinosaurs seems like a very poorly thought out idea beyond the "cool" factor. That's not the world humans adapted to survive in. If they're doing it so that they have a long time before they reach the modern age again, then they have that pesky asteroid to deal with in 20 million years.