Mammalian jawbone diversity: whale vs bat (IMAGE) University of California - Berkeley Caption UC Berkeley doctoral student Sergio Garcia Lara, a co-author of the paper, stands next to a gray whale jawbone while holding a glass vial containing the lower jaw of a bat. The comparison highlights the variety of jaw sizes and shapes that have evolved in mammals, despite the fact that they reduced the number of bones in the lower jaw to one per side, unlike most other vertebrates. Credit Jack Tseng, UC Berkeley Usage Restrictions none License Original 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.