How big was Carbonemys?
Carbonemys was a big turtle. Here are two images that give a good impression of the size of the bones. Below, a line up of skulls shows how much larger the skull found near the Carbonemys shell is compare to the biggest side-necked turtles around today. This image has appeared with an NFL football for scale too, but the soccer ball (or REAL football depending on where you are from) seems a more appropriate scale object for a South American fossil.
The picture below is really cool, because it was not combined in Photoshop. Edwin was actually laying on a table next to the fossil, so the scale is exact. The only modification was whiting out the background!