Extinction Reshaped River Meanders

A University of Michigan team reports that before the dinosaur‑killing impact, rivers in floodplains were straighter and overflowed more often, but after dinosaurs vanished and forests rebounded, rivers shifted to meandering channels. They infer this from sediment layers across the Cretaceous–Paleogene boundary: pre‑impact strata are sand‑ and silt‑rich (frequent overbank floods), while post‑impact layers show fines and features consistent with stabilized, meandering systems. The study argues megafauna loss can cascade into geomorphic change. — It reframes extinctions as drivers of physical Earth systems, implying that modern megafauna loss or rewilding could alter flood regimes, carbon storage, and river management.