Fossil skeleton of a Pteradactyl, from the British Museum's collection | CM Dixon/Print Collector/Getty Images

Mass Extinctions on Earth Coincided With Out-of-Whack Carbon Cycles

Periods during which large percentages of species died off occurred at the same time as big swings in carbon isotopes found in Earth’s geological record.

Sedimentary rocks at Meishan, China contain signatures of a disturbance in the carbon cycle immediately preceding Earth's greatest mass extinction. | Shuzhong Shen