A giant skink with spiky armor and powerful jaws roamed the Australian outback until around 47,000 years ago, according to newly discovered fossils.
In 2009 and 2013, scientists described two mysterious fossils, part of a jaw and skull – found in the Wellington Caves in New South Wales. They appeared to belong to skinks, a type of lizard, but they were unusually large.
Now a more recent excavation at the same site has unearthed dozens of similar fossils. An analysis led by kailah thorn at the Western Australian Museum in Perth has revealed that they all belong to the same extinct species: a skink called Tiliqua fragens – that was about 1000 times heavier than typical skinks alive today.
The closest living relative of the giant skink is rough tilicuaalso known as the shingleback skink, found in dry areas of inland New South Wales and other parts of southern Australia.
By comparing the body measurements of the two species, Thorn and his colleagues estimated that the extinct skink would have weighed around 2.3 kilograms. Most live skinks only weigh around 2 grams, with the heaviest, the shingleback, reaching 1 kilogram.
The dig uncovered a variety of fossils of the giant skink that are 47,000 years old or older, including teeth and parts of its skull, bony armor, backbone and leg bones.
These showed that It had a deep, broad skull, along with powerful jaws and a thick, spiky layer of armor.
It probably wasn’t very fast because it had short, stubby legs, but this wouldn’t have mattered because its armor would have given it protection from predators, Thorn says.
The shape of its teeth suggests that, like today’s shingles, it ate mainly plants. She may have needed strong jaws because she “ate something hard, like hard plant fiber or maybe a fruit or hickory nut that dried up in the summer,” she says.
Since then, Thorn and his colleagues have found other fossils of the species sitting unidentified in old museum collections. These show that it ranged across inland New South Wales and south-east Queensland, locations that were likely dry and open.
The skink lived at the same time as other giant creatures in Australia, including giant kangaroos, wombats and “marsupial lions”, collectively known as megafauna. The skink and other megafauna are thought to have gone extinct more than 40,000 years ago due to the arrival of people or climate change.