Panama fossils help unravel the mystery of how frogs got their shape

Colombian researcher María Camila Vallejo-Pareja is using frog fossils from millions of years ago to understand the shape and distribution of the great diversity of frogs found in Central America today.

Vallejo-Pareja, which is currently a doctoral student at the Department of Biology and the Florida Museum of Natural History (FLMNH) from the University of Florida says the fossils were discovered during the expansion of the Panama Canal more than 10 years ago.

“One of the biggest challenges of working with fossil frogs is that frogs are usually very small and their bones break very easily,” she says, adding that frog skeletons are relatively difficult to study because they are so small and brittle.

“It’s problematic, because the fossils will break (like any fossil!), but the most problematic thing is finding comparison material,” says Vallejo-Pareja.

She says frog skeletons, especially smaller ones, are hard to find in museum collections, but now it’s easier than ever because powerful new imaging machines use computed tomography (CT-scans) to render 3D portraits of fossil creatures. .

“The biggest opportunity is that resources such as CT scans of many species of frogs are now available and they have become my main source of comparison,” she says.

Vallejo-Pareja says that without the scanned fossils as a reference, it would be even more difficult to address the questions that interest him.

“The study of these fossils is very important because frogs today are a very diverse group, especially in Central America, and we don’t know much about their morphological evolution and biogeography,” she says. “Most of what we know is based on other methodologies, like molecular phylogenetics, and fossils are the direct evidence we miss.”

Eureka Moment

Vallejo-Pareja grew up between the cities of Bogota and Medellin in Colombia and says her Eureka moment came during long bus rides through a wide range of ecosystems.

“I was amazed at how much everything changed from being in Bogota, then up into the mountains to a cooler place, then down to Honda and La Dorada to be in one of the places I ‘will always imagine in my head as the hottest places on earth’, she says, ‘after that I wanted to be in nature and study nature’.

During her undergraduate degree in biology at the Universidad Nacional de Colombia in Bogota, Vallejo-Pareja initially focused on botany.

“I moved on to living mammals, then to fossil mammals after starting a class project in comparative anatomy, then for my last undergraduate semester I joined paleontology expeditions with STRI (Smithsonian Tropical Research Institute),” she says, adding that she’s had a wide range of experiences since then.

“Living in so many different cities and countries has been difficult but also amazing,” she says, “as was doing all this traveling with my daughter who was born when I was a student.”

Another Colombian researcher who studies fossils is Dirley Cortes Parra.

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