Exploradio Origins: South America’s Evolutionary Experiment

Nov 29, 2018

"Well, I think one of the real big questions for evolutionary biology is how do the small scale evolutionary processes, genetics and things like that, function over large spans of time?"

Darin Croft is a professor of anatomy at Case Western Reserve University. He teaches head and neck anatomy to medical students, but, he’s also a world-renowned expert on South American paleontology and paleo-mammals.

South America's a really neat place if you're interested in mammals.

"South America’s a really neat place if you’re interested in mammals because for most of the history since dinosaurs went extinct, it was isolated, basically like Australia is today," Croft said. "And it really represents a separate experiment in evolution and that allows us to test a lot of ideas that were developed based on the fossil mammals of other continents."

Croft’s group is trying to determine whether mammals in different places, or times, will evolve to fill ecological niches in the same way, no matter what group they belong to.

"There was a different group of marsupials that evolved to fill meat-eating niches in Australia, things like the Tasmanian tiger, or the thylacine," Croft notes. "But there was a huge group that filled that niche for tens of millions of years in South America that is now extinct, and what we’re trying to figure out is, did they evolve to fill all the same niches that cats dogs weasels and bears fill today? And what it looks like is, in fact, they didn’t, and it seems like that may have limited how many species that they were able to evolve into."