When the famous Chicxulub asteroid struck what is now Mexico's Yucatán Peninsula 66 million years ago, it ended the reign of the nonavian dinosaurs. As ecosystems recovered, small, adaptable mammals rapidly spread into newly vacant niches, evolving new diets, larger bodies and more diverse ways of life until they dominated the land within a few million years.
Now, new evidence suggests that even before the asteroid hit, Earth was already beginning to rot.
A study published May 12 in the journal PNAS found evidence of environmental fungal blooms before and after the Cretaceous-Paleogene (K-Pg) mass extinction event. Looking at microscopic fossils from rocks dating to the K-Pg event in North America, a team of researchers led by Dr. Arturo Casadevall, chair of the Molecular Microbiology and Immunology Department at Johns Hopkins University, identified an earlier fungal bloom dating to roughly 30,000 to 100,000 years before th...


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