image: This is a comparison of the musculoskeletal system between humans and turtles. (Top) In the human skeleton, the scapula is situated outside the ribs, while in turtle skeleton it is located inside the ribs. (Bottom) The muscle plate is added to the top figures. In humans, the muscle plate spans adjacent ribs and occupies the same layer with them, suggesting that the muscle plate can indicate the position of the ribcage. In turtles, the muscle plate runs between the ribs like humans but in its ventral side. It is folded inward (arrow) and can be found inside the scapula, implying that the turtle scapula is outside the presumptive ribcage shown by the muscle plate. This image relates to an article that appeared in the July 10, 2009, issue of Science, published by AAAS. The study, by Dr. Hiroshi Nagashima of RIKEN Center for Developmental Biology and colleagues was titled, "Evolution of the Turtle Body Plan by the Folding and Creation of New Muscle Connections." view more
Credit: [Image courtesy of Shigeru Kuratani and Hiroshi Nagashima]