Exactly, I don't think we need to even worry about stuff like this.
You just read the story of Genesis in the Bible, and the children will either believe it or not believe it. Can't force them to believe anything. If a child has an enquiring mind, and let's face it many boys are absolutely FASCINATED with dinosaurs, they will ask the question of what happened to them, and you can ask them, well, what do YOU think.
When you have evidence that a species lived but you no longer see them around anymore, what do you think happened to them?
In most cases, the animals have been hunted to death, or their habitat changed and they no longer had the food they once had.
There are many reasons, but having lived on a land where there were NO large mammals and had the largest birds of any known to man, (the moas) and birds that have gone extinct (thanks to europeans love of feathers) none of us entertain the notion that whatever is not living or around today must be millions of years old.