Two Students Named a New 309-Million-Year-Old Amphibian Relative After Their Mothers, Both Named Jean
Learn how two Field Museum interns identified Jeanerpeton in a Mazon Creek fossil and what its toe pads reveal about early amphibians.
Payton Kohlberg and Allison Sefcovic, both 2025 Women in Science interns at the Field Museum, have named a newly discovered 309-million-year-old amphibian relative after their mothers, both named Jean. The fossil was found years ago in Mazon Creek, Illinois, and was initially classified as a species already known from the area. However, the students' closer examination revealed it to be a distinct species, leading to its naming as Jeanerpeton mazonensis, or "Jean's crawler."
Co-author Cam So says that A. grandiceps had become a catchall label for several fossils in the Field Museum's collection, and examining them individually could show that some belong to separate species. This publication officially pulls Jeanerpeton out of this "waste bin taxon." The toe pads on Jeanerpeton provide evidence of their presence in a temnospondyl body fossil, suggesting that this feature was already present more than 300 million years ago.
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