Conn Professor Peter Siver’s research, published in the journal Annals of Botany, confirms that during the late early Eocene—approximately 48 million years ago—this region maintained warm temperatures year-round, even during months of winter darkness. The work was done in collaboration with colleagues from Canada and Poland.
Siver’s team identified fossilized phytoliths—microscopic silica structures formed in plant tissues—from palm trees in ancient lakebed sediments extracted from the Giraffe kimberlite pipe locality in Canada’s Northwest Territories. These fossils, alongside preserved remains of warm-water aquatic organisms, indicate a climate far warmer than previously thought, challenging assumptions about when and where ice first formed in the Northern Hemisphere.
“The discovery of palm fossils this far north provides clear evidence that the Arctic was once ice-free, with a climate similar to today’s subtropics,” said Siver. “These findings give us a window into past greenhouse conditions and help refine models predicting future climate change.”
Some of the fossil analysis for this study took place in Siver’s lab at Connecticut College, where students are involved in examining microfossils to reconstruct ancient ecosystems. His ongoing research continues to provide hands-on opportunities for students to contribute to climate science while gaining experience with advanced microscopy and fossil identification techniques.
In addition to confirming the northernmost record of palms during this time, the study also documents, for the first time, fossilized stegmata—linear arrays of phytoliths in palm foliage—establishing that this evolutionary trait had emerged by the early Eocene. The presence of multiple warm-adapted aquatic species further reinforces that this prehistoric Arctic region supported a lush, temperate ecosystem.
Siver’s research contributes to the broader understanding of Earth’s climate history, particularly the extent and timing of ice formation in the Cenozoic era. By reconstructing these past environments, scientists gain valuable insights into how ecosystems respond to long-term climate shifts.
- The paper Palm phytoliths in subarctic Canada imply ice-free winters 48 million years ago during the late early Eocene, about an imaging analysis, was published in Annals of Botany. Authors: Peter A Siver, Alberto V Reyes, Andrzej Pisera, Serhiy Buryak & Alexander P Wolfe.
About Peter Siver #
Charles and Sarah P. Becker ’27 Professor of Botany and Environmental Studies. He is a limnologist and phycologist, with expertise in paleolimnology, microscopy and statistics. Peter is especially known for his work with microscopic algae, especially the synurophytes, chrysophytes and diatoms, and his research spans numerous questions on the ecology, biogeography, phylogeny and evolutionary histories of these groups of organisms. In addition, he uses the remains of siliceous organisms to infer past conditions in lakes spanning time scales of hundreds to millions of years. He is an expert light and electron microscopist, and along with colleague Jan Hinsch has described a unique method of using incident light to vastly improve resolution with a light microscope. Peter has published over 3,500 micrographs and his images have graced the covers of Bioscience, Palaios, Journal of Phycology, American Journal of Botany, Molecular Ecology and Freshwater Biology. Several of his many videos on microbes have appeared on the television show Forensic Files, and on the movie Largest produced by NASA. He has nearly 160 publications with 65 student coauthors, has described 107 new algal genera and species, and has had another six named in his honor. Peter has taught phycology, limnology and environmental science to thousands of students, and earned numerous awards for teaching, research and service.
Contact: notaspampeanas@gmail.com