Much of Anemone’s fieldwork is conducted in the Great Divide Basin of Wyoming. It was there, in 2017, that his team found the most complete skull seen thus far of Esthonyx, a 55 million-year-old mammal similar to modern deer. “Most of the time we find isolated teeth. An entire skull is a trove of information – brain size, nasal cavity, ear structure – giving us information on diet, how they balanced and moved, and more.”
Dr. Bryan McLean, the biologist, is interested in both evolutionary changes in mammals over long time periods, as well as short-term changes in individuals from one season to another.
He’s studied how rodents around the world adapt in both similar and different ways to underground environments, including how their bodies change to allow them to dig. Some species use their forelimbs, some their hindlimbs, others make more use of their mouths.
“We’re interested in the nuance that goes along with that,” he says. “The extent to which there’s trade-offs – the forelimb becomes enlarged, the other limbs aren’t.”
By studying the animals’ anatomy, he hopes to gain insights into how the environment can shape evolution.
He’s also interested in how short-term variations, such as changes in food availability and the weather, can prompt physiological changes – specifically, ones he can track through changes in anatomy.
McClean and his students collected mice from the Appalachian Mountains in North Carolina and discovered that during the winter, when food is scarce, their digestive tracts lengthened by about 35 percent.
That should allow them to extract more nutrients from what food they are getting, he says.
Now, he and his students are measuring the skulls of Sorex shrews – a group of animals that includes dozens of species and subspecies in Europe, Asia, and North America. Research has shown that one European species will reabsorb part of its brain matter – resulting in smaller skulls – when food supplies shrink.
“We have more species in this one genus, Sorex, than exist in Europe, but the phenomenon has never been shown here,” McLean says.
So, McLean and his students go to the western part of the state each season to trap shrews and bring them back to Greensboro for analysis. The micro-CT scanner allows them to create precise, detailed images of the animals’ anatomy.
“We are basically going to do some measurements on the size and shape and look at the brain volume.”
Using a CT scanner means McLean and his students don’t have to clean, preserve and then measure individual skeletons – something that could take years.
Many CT scanners, he says, are booked, and it can become nearly impossible for students to get access to one off campus.
“It’s rapidly speeding up what we could do.”