The discovery of fossils of ancient plants in Washington reveals a mystery of paleobotany

The exposed rock shows a top-down view of the fruit with annular nectaries, one full wing, partial wing, and three worn wings (arrows). Credit Tang, et al.

A new description of two well-preserved ancient fossil herbariums in Washington encourages paleobotanists to rethink how plants disperse during the Late Cretaceous, 66 to 100 million years ago. I am.

Research published in New botanist Details of two fossil winged fruits of the genus Ceratopetalum, previously believed to have been confined to the Southern Hemisphere of the Cretaceous. However, these new fossils were discovered on Sucia Island, Washington. Amazing discoveries have made paleobotanists rethink how their scope really expanded and how it happened.

Keana Tang, Ph.D. student in ecology and evolutionary biology at the University of Kansas, said: KU Institute for Biodiversity and Natural History Museum. “There are still living members in both the Cunoniaceae and the genus Ceratopetalum. What is interesting is that the genus Ceratopetalum is currently only found in Australia. Well, this is because the whole family is confined to the Southern Hemisphere. It’s strange to find fossils all the time. Here in the Northern Hemisphere. I thought, “Wow, how did you get here?”

Tang and her collaborators dubbed a new fossil species, Ceratopetalum suciensis, after the island of Washington where they were discovered.

Today, the modern version of the genus Ceratopetalum is endemic in Australia’s moist rainforests and plays an important role in the ecosystem.

“You will find a forest that is just dominated by these species,” Tang said.

But she said the findings are more important because Ceratopetalum and the larger family Cunoniaceae are part of the “Paleo-Antarctic Rainforest Lineage” or PARL. Therefore, a better understanding of how Ceratopetalum has expanded its range can inform scientists of how major large plant groups have expanded their range throughout the geological era. ..

“They have a common history of being around Antarctica, spreading north over time and changing structural plates, and changing climate. As the Antarctic cools, these plants move to South America, South Africa and Australia. I’m moving, “Tang said. “It’s interesting because all the rainforest strains of the Paleo-Antarctic are expected to originate from the South. The record of this fruit in the Northern Hemisphere raises new questions. The Cunoniaceae are actually international. Did you find it anywhere? Or was this a kind of lucky opportunity that was somehow transported north through the exchange from Antarctica to South America and then to North America? “

The discovery of fossils of ancient plants in Washington reveals a mystery of paleobotany

Keana Tang, lead author and a PhD student in ecology and evolutionary biology at the University of Kansas and the KU Institute for Biodiversity and the Museum of Natural History. Credit: Keana Tang

According to Tang’s KU advisor and co-author, Brian Atkinson, an assistant professor of Ecology & Evolutionary biology A curator of the Department of Paleobotany at the Institute for Biodiversity, the findings highlight new possibilities for bioexchange between North America and South America-South and North America that may have occurred in the late Cretaceous. increase.

“In a way, it’s like finding a penguin in North America,” he said.

The fossils of Ceratopetalum suciensis were collected on the island of Sasia by fossil hunters David Starr and Jim Goedert, and then micro-CT scanned at the University of Michigan by co-author Selena Smith. To classify them with the highest accuracy, Tang then analyzed them layer by layer using a painstaking process called cellulose acetate desquamation technology.

“I started peeling the rock,” she said. “Basically what’s happening is a series of steps to remove the rock surface, polish the fossil surface and soak it in 5% hydrochloric acid for a few seconds. It’s very safe. You can also soak your hands. Acid, and you will still have your fingertips So you soak it in acid for a few seconds, then rinse the rock with water and rinse it with acetone, and you get this plastic sheet in your hand Put it is cellulose Next, spray the surface of the fossil again with acetone and then place the sheet. Throughout this process, you will get a very thin piece of rock, a few micrometer, but because it can pass through. It’s convenient. It picks up the entire fossil and various structures hidden in the rock matrix that can be missed by Micro-CT scans. “

Through these processes, Tang was able to place fossils in the genus Ceratopetalum and raise new questions about how plants spread millions of years ago. In addition, this study suggests that the Pacific Northwest, where Ceratopetalum suciensis was discovered, is a promising area for further research by paleobotanists.

“There’s a lot to investigate, especially on the west coast of North America,” Tan said. “I understand that not many people do such work. It is relatively unstudied. Much of the paleobotany world is located inside the east coast or the west. think.”

Paper New botanist Tang’s first author of research in peer-reviewed journals and her first author as lead author. She grew up in the suburbs of northern Los Angeles, and after she met Atkinson while she was an intern at the Natural History Museum of Los Angeles and learned about his work, she came to KU.

After Tang gets her PhD, her ambition is to continue her discovery as a researcher.

“Ideally I want to work in a museum environment,” she said.

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For more information:
Keana K. Tang et al, Spreading beyond the Gondwana Continent: Cretaceous Cunoniaceae, Western North America, New botanist (2022). DOI: 10.1111 / nph.17976

Quote: The discovery of ancient plant fossils in Washington reveals a mystery of paleobotany (February 15, 2022). Obtained from https: // on February 15, 2022

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