A Monash University study shows the Tasmanian Tiger only weighed about 17 kilograms on average. Image by PR HANDOUT IMAGE PHOTO

Technology

Tasmanian Tigers smaller than thought

2020-08-20 11:32:24

Advanced three-dimensional scanning has been used to establish that Tasmanian Tigers were only about half as big as once thought, changing the way scientists see their position in the Australian ecosystem.

The Monash University study found the thylacine (aka Tasmanian Tiger), only weighed about 17 kilograms on average.

The research, published in Proceedings of the Royal Society B on Wednesday, was led by PhD student Douglass Rovinsky who admits he “spends an uncomfortable amount of time staring at the thylacine”.

Mystery surrounds the Tasmanian Tiger, which has been extinct since the 1930s, has long fascinated scientists and become an icon of Australian biodiversity.

While there’s some archival film footage, the species is a true enigma with almost no direct observations supporting an understanding of their behaviour and biology.

Previously the most commonly used estimate of its body weight was 29.5 kilograms, and the new discovery revises how scientists understand its biology and role in the ecosystem.

It unravels the mystery of the size of the thylacine by bringing together traditional measurement techniques with advanced 3D scanning and volumetric methods, and the largest database of museum specimens that spans six countries and incorporates 93 individual thylacines.

The research, supervised of the BDI’s Dr Justin W Adams and Assoc Prof Alistair Evans from the School of Biological Sciences, established that there were strong differences in the average male and female body size, with the male mean of 19.7kg and female mean of 13.7kg. 

The mixed sex population mean of 16.7kg is well below the 21kg threshold for when predators are likely to take large prey.

“This result also fundamentally challenges prior views about the thylacines as a carnivore, and underscores that thylacines were a predator that evolved to consume prey smaller than themselves,” Dr Adams said.

The new body mass estimates for thylacines place them as specialists on small prey, challenging prior interpretations of them as convergent with species like wolves that specialise in pack-hunting prey substantially larger than themselves.

“Rewriting the thylacine as a smaller animal changes the way we look at its position in the Australian ecosystem – because what a predator can eat is very much dependent on just how big they are,” Mr Rovinsky said.

“Many of the 19th century newspaper reports just might have been ‘tall tales’ – told to make the thylacine seem bigger, more impressive … and more dangerous!”