So Big!

"Why did the big dinosaurs grow so big?"

If you were me, would you be ready to answer this one?  Oddly enough, Christopher asked this question just last week.  I had no answer.  Just a slight head tilt and a blank stare.  Luckily, I found the answer in today's NY Times in an article called "So Big!"  So when the twins decide to ask me, I'll know the answer!