Wet weather at the end of the last ice age appears to have helped drive the ecosystems of large grazing animals, such as mammoths and giant sloths, extinct across vast swathes of Eurasia and the Americas, according to our new research.
The study, published in Nature Ecology and Evolution today, shows that landscapes in many regions became suddenly wetter between 11,000 and 15,000 years ago, turning grasslands into peat bogs and forest, and ushering in the demise of many megafaunal species.
By examining the bone chemistry of megafauna fossils from Eurasia, North America and South America over the time leading up to the extinction, we found that all three continents experienced the same dramatic increase in moisture. This would have rapidly altered the grassland ecosystems that once covered a third of the globe.
The period after the world thawed from the most recent ice age is already very well studied, thanks largely to the tonnes of animal bones preserved in permafrost. The period is a goldmine for researchers – literally, given that many fossils were first found during gold prospecting operations.
Our work at the Australian Centre for Ancient DNA usually concerns genetic material from long-dead organisms. As a result, we have accrued a vast collection of bones from around the world during this period.
But we made our latest discovery by shifting our attention away from DNA and towards the nitrogen atoms preserved the fossils’ bone collagen.