Mónica Carvalho and Selena Smith uncover flowering plants’ origins in the Southern Hemisphere

For paleobotanists Mónica Carvalho and Selena Smith, assistant and associate professors, respectively, in EARTH, the reality of spending January through March isolated on the Antarctic Peninsula set in when their ship set sail. 

“I thought, ‘Okay, now it’s real,’” Smith said. “They left us on this rocky island for 40 days, in our tents, and it was actually a really fun time.”

Smith and Carvalho were there with an international, interdisciplinary team of scientists to paint a much-needed picture of Antarctica’s forests during the Cretaceous. During that period, Earth was in a greenhouse climate, and angiosperms—flowering plants—were beginning to take off. Today, angiosperms are the most diverse and abundant kind of plant. To understand their fates in an ever-changing climate, we need to understand how they survived and adapted in the past.

Fossil evidence from the Northern Hemisphere suggests angiosperms diversified rapidly during the Cretaceous, but much less research has been done on angiosperms in the Southern Hemisphere, due in part to its smaller land mass.

During the Cretaceous, Antarctica was at a similar latitude as today, and it was covered in lush rainforests. West Antarctica is one of the few places known to have fossil plant material from the Late Cretaceous, so it holds clues to Southern Hemisphere angiosperm evolution: What plants were there? How diverse were these forests? Do today’s Southern Hemisphere plants have roots in the Antarctic Peninsula?

To find out, Smith, who is a co-PI with the University of Kansas’ Brian Atkinson, and Carvalho were sifting through ancient deltas on the Antarctic Peninsula, looking for concretions: brown, potato-esque rocks that may not look like much on the outside. But they preserved fruits and seeds exceptionally well.

“The level of detail that we can get is absolutely outstanding,” Carvalho said. “Seeds and fruits, preserved in 3D. And tissues of such high quality that we could see cell structures with a hand lens.

”Over six weeks, the team collected about 9,000 pounds of concretions and other samples, which finally arrived at the University of Kansas for processing in the middle of July 2024. It’s early, but the results seem promising.

“We’re in the initial stages of figuring out what we got,” Smith said. “But the early ones look just as we were hoping they would in the field.

”Smith brings her expertise with CT scanning of fruits and seeds and a familiarity with this mode of preservation, while Carvalho is an expert in Southern Hemisphere paleoecology and tropical angiosperms—a passion she attributed to growing up in lush Colombia. (“I grew up in Alberta,” Smith added. “Not very lush.”)

Together with the rest of the team, they’ll reconstruct Antarctica’s dense Cretaceous forests, one concretion at a time.