Discover past climates through paleobotany

Paleontology has long offered scientists insight into the mysteries of prehistory. Through excavations of colossal skeletons, petrified insects and fossilized plants, researchers can uncover what life was like long ago.

Despite extensive study of animals from the Cretaceous period, which spanned from 145.5 million years ago to the extinction of the dinosaurs 65.5 million years ago, little is known about things about the climate of that time, especially in the eastern parts of Canada. Researchers at McGill’s Redpath Museum have taken a different approach to filling these knowledge gaps, using paleobotany, the study of fossilized plants.

“The fossil record is rich in assemblages of ferns, angiosperms, and coniferous leaves that offer clues to the plant diversity of past ecosystems”, Alexandre Demers-Potvin, graduate student and 2018 National geographic Explorer, wrote in an email to The McGill Tribune. “Not only do fossil plants offer insight into the vegetation of past landscapes, but some of them […] can be used to predict the climate of this past landscape.

Last summer, Demers-Potvin, the principal author of a recent to study on paleoclimatic reconstruction, and a team of researchers under the supervision of Professor Hans Larsson, director of the Redpath Museum, traveled to Schefferville, a town near the Quebec-Labrador border. Among the researchers were Noémie Sheppard, undergraduate student in environment, as well as Michel Chartier and Mario Cournoyer, co-founders of the Université de Montréal. Museum of Paleontology and Evolution (MPE), which also supported the study. They centered their analysis on insect fossils and angiosperm, or flowering plant, specimens from the area, known as the Redmond flora.

Among the ruins of an abandoned mine, the team found remains of angiosperms preserved in sedimentary rock, which served as the first clue to Late Cretaceous environmental conditions. The composition of the rocks and the broad leaves of the fossils suggest that they formed at the bottom of a lake surrounded by forest.

Demers-Potvin and Larsson found that Schefferville experienced an average annual temperature of 13 to 17 degrees Celsius during the Upper Cretaceous. Although it would have been cooler for North America at the time, the creatures there would have enjoyed moderate humidity and warm summers.

Remarkably, these data were extracted from plant leaves. Because Cretaceous flowering plants are anatomically similar to those of today, researchers can extrapolate climate information from fossilized plants in the same way that they can infer this information from modern plants. Demers-Potvin and his team derived elements of the past environment using a tool called Climate Leaf Analysis Multivariate Program (TO SQUEEZE) .

“[CLAMP] is based on the premise that certain anatomical traits of leaves are correlated with certain climatic parameters [such as] Temperature [or] precipitation,” Demers-Potvin wrote.

As a data analysis system, CLAMP uses a scoring method to track how modern plants adapt to their environment. Referring to the fossil record, he then works backwards to associate the same traits in older plants with their potential environmental context. The results can be used to understand the effects that drastic climate change had on species thousands of years ago, and how this translates into potential effects on species in the current climate crisis.

In addition to sampling with CLAMP, the research team unearthed 15 new plant species that were previously unknown in the region. Surprisingly, the taxonomic record of Redmond’s flora had not been measured significantly since the 1960s.

Beyond the Cretaceous explorations led by Demers-Potvin, which aims to continue the team’s research with insect fossils found in Schefferville, Larsson oversees multiple evolving field projects, ranging from studies of alligators off the coast of Mexico to Dinosaur Provincial Park in Alberta. Larsson thanked the Redpath Museum for allowing scholars to explore diverse interests.

“None of this would be possible without the Redpath Museum,” said Professor Larsson. “You are not locked in here.”