Abigail Curtis, a postdoctoral fellow at the American Museum of Natural History in New York, demonstrates how computed tomography reveals unexpected scientific insights into bat physiology. X-ray with computed tomography is used to create digital reconstructions of modern and fossilized bat samples. These images enable research into how bat species have developed specialized anatomy for eating, communicating, and locating food. Most importantly, researchers are using non-destructive testing methods to share digital scans of bats to collaborate on a global scale.

Examining Bat Evolution

Bats are actually the second most diverse group of mammals. So, next to rodents, which have about 2,000 species, bats have between 1,300 to 1,500 species and they all just get weirder and weirder the harder you look through the list of species. When you get underneath at what their faces look like and look at the bones, you see that the structure of the bones is also really different among species.These structures or these differences relate to how they use their skulls.

This is my new favorite picture. So, all the cool kids now in biology are doing soft tissue X-ray CT examinations. So this bat here (image at right) looks like it got into a bag of Cheetos, but it's actually a nectar feeder. It got its face inside of the plant and got pollen all over its face. With CT scans, and you can see a lot of really interesting things about the tissue, including the brain, and specifically, the cerebellum, which is involved in balance and perception of movement. We can see density variations on the brain, nasal chamber features, soft tissue lining, and then also the muscles surrounding the skull.

What you can do with these scans is you can go through and get these soft tissues out and place them back on to the bone. In this image (at right) a bat skull with the jaw closing muscles here in red and blue, and this is the jaw opening muscle here in purple. And so then you can start to understand how are the muscle fibers are oriented, how do they change orientation if you scan a bat that has its mouth closed versus open, how does it compare among different types of mammals.

In this last image (at right), we have a bat type of carnivore, a weasel-like animal, a shrew, and a type of rodent. Maybe something like a muskrat type animal, but a little bit smaller. So you can look at how these different parts of the muscles differ in proportion among species. For something that's feeding more on plants, it's emphasized more of this blue muscle. Whereas this guy (shown in the upper right of the four animal views), that's feeding on really hard fruit and needs to have really high bite forces with its mouth wide open, has a really big red muscle here attaching to the top. So you can start to understand the evolutionary patterns in the jaw closing muscles and how that relates to feeding.