Play concentration with me. Click on the boxes, get two hidden boxes the same and WIN! (OK, so you dont win much.) (Watch the bottom of the picture.)

Picture borrowed from Science (the AAAS Journal) and undoubtedly copyright by them. I hope they don't mind - this picture deserves wider viewing than was likely in the journal. The original caption read :
"A stretch. Large animals such as Tyrannosaurus or a 6000-kg chicken couldn't carry enough leg muscle to run."

Somehow it always makes me think of Chicken Boo.