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* OVER 2.6 MILLION YEARS SOUTHEAST ASIA WENT FROM TROPICAL TO GRASSLAND AND BACK  * BECOMING A SAVANNAH HABITAT WITH RICH GRASSLANDS ALLOWED MEGAFAUNA TO THRIVE * AS THE CLIMATE CHANGED AND

IT BECAME TROPICAL AGAIN THE GRAZING SPECIES DIED OFF * RESEARCHERS STUDIED CHEMICALS IN FOSSILS TO MAP THIS HISTORY OF MEGAFAUNA AND SAY THE SAME COULD HAPPEN TO MODERN LARGE BEAST AS THE

WORLD GETS HOTTER By RYAN MORRISON FOR MAILONLINE Published: 11:00 EDT, 7 October 2020 | Updated: 11:18 EDT, 7 October 2020 Giant beasts that roamed Southeast Asia 100,000 years ago

alongside our ancient human ancestors were killed off by climate change, researchers claim.  Elephants the size of double decker buses, the biggest ape that ever lived, and Homo erectus were

all driven to extinction by a loss of grassland as the climate changed.  Looking at chemical records in modern and fossil mammal teeth, the researchers were able to reconstruct whether past

animals predominately ate tropical grasses or leaves - as well as the climatic conditions at the time they were alive.    Over a million years or so the climate changed from rainforest to

grassland, allowing grazing animals to thrive, before changing back to rainforest where only smaller creatures and modern Homo Sapiens were able to thrive.  The discovery, by Griffith

University, Brisbane, has implications for the large animals living today - with authors saying they face being wiped out by global warming.  Gorillas, lions, tigers, rhinos and other iconic

terrestrial beasts will be lost forever unless carbon emissions are reduced, says lead author Julien Louys. As part of the study the researchers compiled stable isotope data for sites

spanning the Pleistocene - the last 2.6 million years - from teeth and other fossil records. They also added over 250 new measurements of modern Southeast Asian mammals - representing

species that had never before been studied in this way. The team found rainforests dominated the area from present-day Myanmar to Indonesia during the early part of the Pleistocene. 

'Southeast Asia is often overlooked in global discussions of megafauna extinctions,' according to Louys of Griffith University. 'But in fact it once had a much richer mammal

community full of giants that are now all extinct,' including Elephant-like Stegodon that was 13ft tall with straightened tusks stretching out up to nine feet in front of the beast.  It

shared the plains of Southeast Asia with oversized hyenas, tapirs, rhinos, water buffalo, goats and deer over 100,000 years ago. There was also Gigantopithecus - the largest known primate

which stood more than ten feet tall and tipped the scales at over half a ton.    The rainforests began giving way to grasslands through the Pleistocene, support a rich community of grazing

animals including the Stegodon. These were hunted by our early human ancestors - enabling them to thrive and the drastic change to a grassland ecosystem was a boon to some species.  However,

it also led to the disappearance of other animals - like Gigantopithecus.  The tropical canopies began to return around 100,000 years ago, pushing the grasslands away - with the canopies

came a rise in classic rainforest fauna that are the ecological stars of the region today. The loss of many ancient Southeast Asian megafauna was found to be correlated with the loss of

these savannah environments, the team said. Likewise, ancient human species that lived there such as Homo erectus - the first to walk upright - were unable to adapt to the re-expansion of

forests. Dr Roberts said: 'It is only our species, Homo sapiens, that appears to have had the required skills to successfully exploit and thrive in rainforest environments. 'All

other hominin species were apparently unable to adapt to these dynamic, extreme environments.' Ironically, it is now rainforest megafauna that are most at risk of extinction. Many of

the last remaining species are critically endangered throughout the region as a result of the activities of the one surviving hominin in this part of the world. Prof Louys added:

'Rather than benefiting from the expansion of rainforests over the last few thousand years, Southeast Asian mammals are under unprecedented threat from the actions of humans.

'Taking over vast tracts of rainforest through urban expansion, deforestation and overhunting, puts us at risk of losing some of the last megafauna still alive.'  The findings have

been published in the journal Nature.  EARTH HAS HAD FIVE GREAT EXTINCTION EVENTS WITH THE MOST FAMOUS A DINOSAUR KILLING ASTEROID Five times, a vast majority of the world's life has

been snuffed out in what have been called mass extinctions. End-Ordovician mass extinction The first of the traditional big five extinction events, around 540 million years ago, was probably

the second most severe. Virtually all life was in the sea at the time and around 85% of these species vanished. Late Devonian mass extinction About 375-359 million years ago, major

environmental changes caused a drawn-out extinction event that wiped out major fish groups and stopped new coral reefs forming for 100 million years. End-Permian mass extinction (the Great

Dying) The largest extinction event and the one that affected the Earth's ecology most profoundly took place 252 million years ago. As much as 97% of species that leave a fossil record

disappeared forever. End-Triassic mass extinction Dinosaurs first appeared in the Early Triassic, but large amphibians and mammal-like reptiles were the dominant land animals. The rapid mass

extinction that occurred 201 million years ago changed that. End-Cretaceous mass extinction An asteroid slammed down on Earth 66 million years ago, and is often blamed for ending the reign

of the dinosaurs.