Huge "elephant bird" fossils
Thousands of years ago, on the island of Madagascar, humans lived with behemoths such as giant lemurs, dwarf hippos, giant tortoises and the world's largest bird, the elephant bird.
Today, these species are long gone extinct. This has forced scientists to figure out whether climate change or human interference is the culprit for their disappearance.
A new study shows that despite the "drought" of the time, which created a harsh environment for the survival of the elephant birds, they still stubbornly survived; and humans became the "last straw" that crushed the beast.
Humans once lived with large animals such as elephant birds, giant lemurs, dwarf hippos and giant turtles
Fossils show that this huge creature went extinct 1500 years ago, but until now, the reasons are unclear.
A team of researchers from Xi'an Jiaotong University in China traveled to Rodriguez, a remote island in eastern Madagascar, to sort out the region's climate history and search for the causes of the extinction of elephant birds.
The team ventured into caves on the island to analyze the concentrations of oxygen, carbon and other trace elements in the deposits, such as stalactites and stalagmites that form when minerals deposited by water droplets.
This sediment grows in layers, similar to tree rings, reflecting fluctuations in temperature and precipitation. Layer by layer, the team reconstructed the climatic chronology of the southwestern Indian Ocean, particularly Madagascar, Rodriguez and another island of Mauritius, which dates back 8,000 years.
Analysis of cave sediments shows that the region has experienced a series of exceptional droughts that have lasted for decades. The most recent drought period was about 1500 years ago– when almost all megafauna species went extinct.
But Madagascar's wildlife has experienced more severe droughts before; therefore, scientists say, the arid climate is unlikely to wipe them out.
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Madagascar is a huge island with an extensive ecosystem and local climate. However, archaeological records show that the presence of humans increased during this period.
With habitat destruction, over-hunting, disease, fires and an increase in agriculture – these enormous pressures, combined with drought, eventually led to the end of the Megafauna of Madagascar.
In just a few centuries of human colonization, the native wildlife of Rodrigues Island and Mauritius has been destroyed. For example, Rodriguez lost the "saddleback Rodriguez Giant Tortoise"; the famous "Dodo", too, disappeared from Mauritius.
"The story of our data is the resilience and adaptability of island ecosystems and fauna to withstand the severe climate fluctuations of past generations — and their eventual demise is clearly impacted by human activity," the researchers said. ”