Blame the wet weather for the demise of the megafauna that once roamed the earth some 15,000 to 11,000 years ago. A new study suggests that the once healthy grazing lands turned into peat bogs and forests, pushing the large animals such as the giant sloths and mammoths into extinction. This catastrophic event happened just after the last ice age.

When the wetter season kicked in, all three continents that include Eurasia, North America, and South America were affected. This event drastically altered the lush pasture and left the giant sloths and mammoths scrambling for vegetation. Because of the mass extinction of these grazing animals, most of their bones were preserved in the permafrost.

According to the Australian Center for Ancient DNA, tons of fossils were literally scattered. These remains from the giant sloths and mammoths provided several genetic materials and specimens for further study. These also made it possible to study the bone chemistry of the megafauna species. One of the recent focus is the nitrogen atoms that were preserved in the bone collagen.

There is a specific ratio of the nitrogen isotopes in fossil bones of extinct giant sloths and mammoths. However, this ratio can be altered once there are changes in the environmental conditions. Given the case of the two megafaunas, the isotopes from the tissue of plants subsequently transpired in the bones of giant sloths and mammoths. Basically, lesser nitrogen-14 isotopes in bones reflect the wetter environment, PhysOrg said.

The research also stressed that apart from the giant sloths and mammoths, they studied hundreds of bones like prehistoric bison, llamas, and horses. All of the 511 specimens that were dated from the last ice age thaw manifested an offshoot in moisture. This moisture spike is known to have coincided with changes in environmental landscapes.

Apart from incessant rains, giant sloths and mammoths also suffered from newly formed lakes and rivers. These bodies of water were formed after the ice sheets retreated and collapsed.