A guy went to a museum to see a dinosaur bone exhibit. He walks around the galleries and is quite impressed by the reconstruction of these ancient animals - a T-rex, a triceratops and more. He sees a guy who works for the museum standing near one of them and says to him. "They're quite a sight. How old are they anyhow?" The guy who works for the museum, says "This one, the T Rex, is 66 million years old and six months". "Wow" the guy responds. "It is amazing that they can be that specific. How do you know?" "Well" the worker says. "He was 66 million years old six months ago and that's when I started working here".