image: Modern mammals, such as the dog and the platypus, have segmented hyoid bones with mobile joints, arranged in saddle-like configuration. The mobile hyoids apparatus supports the tongue and link the pharunx with the larynx and the opening of esophagus. This structure plays a crucial function in transporting and swallowing of the masticated food and fluid in mammals. The new fossil of Microdocodon shows that its hyoids have the jointed segments, and arranged in a saddle shape, as those of modern mammals. This structure is different from the hyoid rods of the Triassic Thrinaxodon, a distant cynodont relative to mammaliaforms. This suggests that crucial transformation to the mammal-like hyoids occurred in the common ancestor of Mesozoic mammaliaforms and modern mammals, but before the rise of modern mammals. This material relates to a paper that appeared in the 19 July issue of Science, published by AAAS. The paper, by C.-F. Zhou at Shenyang Normal University in Shenyang, China, and colleagues was titled, "New Jurassic mammaliaform sheds light on early evolution of mammal-like hyoid bones." view more
Credit: April I. Neander, the University of Chicago