Giant reptiles once ruled Australia. Their loss sparked an ecological disaster | Science


A huge Komodo dragon relative, Megalania, stalks a herd of giant herbivorous marsupials.

Laurie Beirne

BRISBANE, AUSTRALIA—Saber-toothed felines, short-faced bears, and other relentless mammals were the leading predators of the glacial epoch throughout the majority of the world. However not in Australia. Here, reptiles ruled: land-living crocs, monstrous snakes, and massive family members of the Komodo dragon, according to a research study provided the other day at the yearly conference of the Society of Vertebrate Paleontology here. The disappearance of these animals, the scientists argue, included mammalian predators to take control of and set the phase for an enormous termination crisis that sped up when Europeans got here 200 years earlier.

“Between the expansion of agriculture in Australia, which changed the landscape, and the predators that we brought in, there was no way for native animals to escape,” states Kenny Travouillon, a paleontologist at the Western Australian Museum in Perth who was not associated with the research study.

The brand-new image emerged after Gilbert Cost, a paleontologist at the University of Queensland in St. Lucia, Australia, and coworkers searched the clinical literature on brand-new fossil discoveries from the past 15 years approximately. Combined, the finds revealed that Australia had a much higher variety of glacial epoch reptiles than is commonly accepted. These consist of 200-kg family members of Komodo dragons, 3 to 4 times the size of those around today, and long-legged, land-living crocodiles. Cost and others have actually likewise made brand-new unpublished fossil discoveries that reinforce the concept of a continent controlled by reptilian predators for much of the past 25 million years, up till a minimum of 100,000 years earlier.

“We think of the age of the dinosaurs as when reptiles like dinosaurs and crocs were dominant,” states Larisa DeSantis, a paleoecologist at Vanderbilt University in Nashville who was not included with the research study. “So, it’s exciting to think Australia was dominated by reptilian predators in its recent history.”

Travouillon states the concept that Australia was once controlled by reptiles was very first proposed in the 1990s. However it fell out of favor as some research study rather concentrated on native mammal predators, such as the marsupial lion, Thylacoleo. Nevertheless, a much better understanding of Australia’s fossil record is validating “that originally the land predators were reptiles,” he states.

The majority of these big reptiles, and the just big native mammal predators, had actually lastly disappeared by about 40,000 years ago in addition to Australia’s other megafauna, potentially since of altering environment. That left just little mammalian predators like the dog-size Tasmanian tiger and the even smaller sized Tasmanian devil to enter the function of peak predators throughout the continent. Cost recommends these left environments out of kilter.

Things worsened about 4000 years earlier when individuals presented the dingo, a placental mammal from Asia that was a more effective hunter than the Tasmanian tiger or devil and rapidly outcompeted them. However it was the European intro of the feline and the red fox in the past 200 years that has actually triggered the most harm. These animals ravaged little marsupials, which had actually developed together with the reptiles however were not utilized to handling more smart and reliable placental mammal predators.

“Our research demonstrates that it’s not normal for our continent to be dominated by placental mammals as top predators,” Cost states, which have “reigned unchecked in the absence of the now-extinct ice age giants.”

The dingo was most likely accountable for the loss of the Tasmanian devil and Tasmanian tiger. However felines and foxes have actually been linked in the loss of 28 to 30 types and subspecies of Australian mammals in the past 200 years. “That represents 50% of global mammal extinctions over that time,” he states, “which is an absolute ecological disaster.”

And everything started with the disappearance of the glacial epoch reptiles, Cost argues. “We’re still facing the ecological fallout of their losses.”

*Correction, 11 October, 5: 50 p.m.: An earlier variation of this story misstated the approximated size of the Komodo dragon family members. 

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