The 165 million year old fossil of Microdocodon gracilis, a tiny, shrew-like mammal, reveals the earliest example of recent hyoid bones in mammal development.
The hyoid bones connect the back of the mouth, or pharynx, to the openings of the esophagus and the larynx. The hyoids of recent mammals, including people, are organized in a “U” form, much like the saddle seat of kids’ swing, suspended by jointed segments from the skull. It helps us transport and swallows chewed food and liquid—a vital function on which our livelihood relies upon.
Mammals as a complete are way more subtle than different living vertebrates in chewing up food and swallowing it one small lump at a time, as an alternative of gulping down big bites or entire prey like an alligator.
“Mammals have change into so numerous today by way of the evolution of numerous methods to chew their food, whether it’s insects, worms, meat, or plants. However no matter how differently mammals can chew, all of them must swallow in an identical manner,” mentioned Zhe-Xi Luo, Ph.D., a professor of organismal biology and anatomy at the University of Chicago and the senior writer of new research of the fossil, printed this week in Science.
“Basically, the specialized way for mammals to chew after which swallow is all made possible by the agile hyoid bones behind the throat,” Luo stated. This modern hyoid apparatus is mobile and permits the throat muscle tissue to control the intricate features to transport and swallow chewed food or drink fluids.