Adult Lizards (IMAGE) BMC (BioMed Central) Caption The chameleon's exceptional tree-climbing ability is dependent on vital ball-and-socket joints in its wrists and ankles, according to research published in the open access journal BMC Evolutionary Biology. The study also finds that chameleons have twice the number of wrist and ankle skeletal elements than previously thought, and explains how they evolved to live in the trees. Credit Diaz and Trainor, <em>BMC Evolutionary Biology</em> 2015 Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.