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Closer Look: Fossilized Plants Predict Future Mass Extinctions

What if fossilized and living plants could act as an alert system for extreme climate change and even mass extinction?

Paleobotanist and Young Explorer Jeff Benca thinks they can. He’s searching for the subtle signs of the next potential global ecosystem collapse traceable in the tiniest of mutated pollens, grains, and spores. Using this evidence, Jeff hopes to discover what really happened during the greatest mass extinction of all time- and how to detect the next one.

Extinction by Volcano

To find out, Jeff looks at a wide range of prehistoric plant lineages, some fossilized, some living. “We still have many plant groups that lived through the largest mass extinction in history,” explains Jeff.

The End-Permian Triassic Ecological Crisis, Earth’s most devastating extinction, raged roughly 252 million years ago. Popular theory claims the extinction wasn’t the result of an asteroid collision, but rather the biggest volcanic eruption in Earth’s history.

Earth’s largest super-volcano, the Siberian Traps, spewed lava across an area the size of Russia over a span of about one million years- a blast so great, cosmic UV radiation bombardment may have fried much of the world’s forests as well as significantly depleted Earth’s ozone shield.

Coinciding with the eruptions and the disappearance of forests, fossil evidence of concentrated mutated pollen began to appear across all major continents. Jeff points out with some concern that we see the same mutated pollen today in areas near the current hole in the ozone layer in New Zealand.

Jeff is now attempting to replicate the same aberrant pollen and abnormal spores found in the fossil record by conducting experiments growing living relatives of the Permian plants under lethal UV radiation exposure.

Leaf Shape Tells All

Thankfully, mass extinction doesn’t happen often. By comparison, climate change does. However, scientists face some difficulty testing their hypotheses on terrestrial climate conditions in the deep past with much accuracy. Jeff believes plants can change this. To answer the question of when drastic climate change occurred in deep time, Jeff looks at two ancient plant groups: ferns and lycopods (clubmosses).

Modern ferns similar to those that existed 360 million years ago. Photo: Chris Johns/National Geographic Stock

Paleobotanists have long noticed that, in flowering plants, cooler climates yield leaves with a complex serrated edge, like maple or oak leaves. This is due to the plant’s need for more surface area to photosynthesize. On the other hand, warmer climates yield leaves with a smooth edge, like banana leaves.

Tropical, warm climates yield leaves with a smooth edge, while warm climates yield leaves with a complex serrated edge. Photo (left to right): George F. Mobley/Michael S. Yamashita/National Geographic Stock

By using leaf shape as an indicator of temperature, Jeff hopes he can hypothesize when ice ages and periods of warming occurred by looking at fossilized plants.

Sounds easy enough, but there’s a problem. Flowering plants only date back 120 million years in the fossil record and although that might sound like long time ago, plants began sprouting on land over 500 million years ago.

Ferns however, have been around for over 360 million years and clubmosses, 415+ million years. Both present a much better sample to study deep time with and are the subject of Jeff’s latest research question: Does fern and clubmoss leaf shape react the same way to climatic changes as flowering plants?

To find an answer, Jeff is not only looking through the fossil record, but also conducting experiments on  by simulating warm and cool temperatures in a growth chamber to see how they react.

Extreme Botany?

Contrary to popular belief, botany fieldwork can result in some pretty perilous predicaments.

Our interview with Jeff took a comical turn when he recounted a particularly jarring incident when he and his partner almost landed themselves in the jaws of an animal trap big enough to take a leg off.

Unknown to the team, the dense Hawaiian cloud forest they conducted their research in was blanketed with traps meant to eradicate the island’s invasive wild boar population.

“We realized there were ten traps within just five feet of us. We just happened to blunder through the safe way”, laughs Jeff.

Did we mention two-mile hike back to the car and four-hour drive to the nearest city? Park officials could have easily caught themselves a paleobotantist that day. We’re sure glad they didn’t though.