Tasmanian tigers, otherwise known as thylacines, were about half the size scientists once estimated them to be. This development has suggested that the now-extinct marsupials were about the size of large coyotes rather than wolves.
Thylacines, with their defining striped coats and an odd combination of features, went extinct about 2,000 years ago everywhere except the island of Tasmania. When settlers began establishing sheep and cattle farms in Tasmania in the 1800s, thylacines were blamed for livestock losses that were actually due to feral dogs and human mismanagement.
The shy, semi-nocturnal thylacines were hunted down to the point of extinction. The last thylacine living in captivity, named Benjanmin, died from exposure in 1936 at the Beaumaris Zoo in Hobart, Tasmania. This was shortly after thylacines had been granted protection status, but it was too late to save what researchers call an “icon of Australian biodiversity.”
These creatures, once estimated to be about 65 pounds, were really only about 37.5 pounds on average and rather cat-like, new research has suggested. The study published Tuesday in the journal Proceedings of the Royal Society B.
Researchers used advances in 3D scanning and analysis to study 93 thylacine museum specimens from six countries. The scientists discovered that males averaged about 42 pounds and females reached 30 pounds, which shifts the understanding of their role in the Australian ecosystem.
This misunderstanding about their size led farmers to believe thylacines could be dangerous to livestock. But an analysis of thylacine skeletons showed their smaller bodies weren’t adapted to handle the stress of hunting larger prey.
Predators more likely to take on large prey, like wolves, are typically 46 pounds or larger. Instead, thylacines likely hunted small prey and probably didn’t hunt in packs to take down prey much larger than themselves.
“Finding out that they were smaller than previously thought really does change our views on the predatory behaviour of the thylacine,” said Douglass Rovinsky, lead study author and postdoctoral student at Monash University in Australia, via email.
Farmers were wrong in assuming thylacines could kill their livestock. “It was probably a mid-sized predator, doing what mid-sized predators do best: hunting and eating small animals,” Rovinsky said. “And, it also moves the thylacine further away from the idea of it being a “marsupial wolf,” because wolves are big, highly-specialised predators of big, dangerous prey.”
Instead, thylacines likely hunted anything under 18 to 22 pounds, like small marsupials including bandicoots, pademelons, bettongs and small wallabies.
The mysterious life of thylacines
Although the last of the thylacines died out in captivity in the 1930s and there is actual video footage of them, thylacines present a mystery to researchers because there are no direct observations to suggest information about their behavior and biology.
As marsupials, both males and females had pouches but they served different purposes, Rovinsky said. Female thylacines carried their young in their pouches. The males had scrotal pouches into which they could retract their scrotum, but it’s still unknown why.
A very distantly related yapok, or water opossum, used it to insulate and protect the scrotum while swimming, but thylacines weren’t likely to be swimming around, he said.
Thylacines had more cat-like front legs and feet that could rotate, spread and even grasp, unlike dogs. Their back feet also included a naked pad along the entire bottom surface from toe to heel, and they walked on the whole surface of their back feet, which is also something dogs don’t do.
The thylacine family stretched back over 35 million years, so these were the last members of the family, Rovinsky said.
“It’s really interesting to think about the older members of the thylacine’s family – some of which were probably only the size of a cat, and others (related members of the family) would have been bigger than the thylacine,” he said. “Did they have stripes, or scrotal pouches? How similar (or different) were they from the thylacine? We don’t know, but certainly do wish we could!”
Rovinsky and his fellow researchers want to establish a much clearer picture of how thylacines fit into their ecosystem and “what it was that we lost when we drove it to extinction.”
“I think that at the end of the day, that’s where I’d like my research on the thylacine to end up: treating the thylacine as its own animal, and trying to understand it as it really was – not as a weird marsupial reflection of the European wolf,” he said.