World's largest living lizard revealed as Australian for first time

30 September 2009

New scientific research reveals the world's largest living lizard species, Indonesia's Komodo dragon, most-likely evolved in Australia three to four million years ago.

Queensland Museum Senior Curator of Geosciences Scott Hocknull and colleagues from Malaysia, Indonesia and Australia authored the research paper released today by PLoS ONE, challenging the long-held scientific belief that the Komodo dragon evolved from a small ancestor in isolation on the Indonesian islands.

Mr Hocknull said the evidence suggests that the largest ever land-dwelling lizard species evolved on mainland Australia and at least two of them dispersed westward to the islands of Timor, Flores and Java over the last million years.

"The fossil record shows that over the last four million years Australia has been home to the world's largest lizards, including a five metre giant called Megalania (Varanus prisca)," Mr Hocknull said.

"Now we can say Australia was also the birthplace of the three-metre Komodo dragon (Varanus komodoensis).


"Over the past three years, we've unearthed numerous fossils from eastern Australia dated from 300,000 years ago to approximately four million years ago that we now know to be the Komodo dragon.

"When we compared these fossils to the bones of present-day Komodo dragons, they were identical," he said.

The paper also references independent genetic research that shows the Komodo dragon's closest living relative is the Australian lace monitor (Varanus varius), leading Mr Hocknull to describe Australia as a hub for lizard evolution.

"These discoveries show the Komodo dragon most-likely evolved on mainland Australia around three to four million years ago, and then dispersed west to Indonesia, finding a home on the smaller island of Flores around 900,000 years ago," Mr Hocknull said.

"We have dispelled the idea that the Komodo dragon evolved to its large size in Indonesia because of a specialised diet of dwarf elephants. Instead, the Komodo dragon has retained its body size over its four million year old history.

"The most recent fossil discoveries found in Queensland's Mt Etna Caves region show that the 70 kilogram, three metre-long Komodo dragon roamed Australia as recently as 300,000 years ago, and disappeared from the landscape sometime after that.

"This find is also significant in that it shows that the Komodo dragon existed alongside Australia's other giant monitor lizard, Megalania, which was once the world's largest terrestrial lizard until it died out around 40,000 years ago, leaving the Komodo dragon as the living record holder," Mr Hocknull said.

The research paper also heralds the discovery of a new species of giant monitor lizard found on the island of Timor, with three fossil specimens indicating the existence of a lizard larger than the Komodo dragon but smaller than the five-metre Megalania.

Although the Komodo dragon has had a long stable history, it is now found on just a few isolated islands in eastern Indonesia and is vulnerable to extinction.

It is hoped that the Queensland Museum's research will contribute to the conservation of the Komodo dragon whose numbers have contracted severely in the past 2,000 years due to habitat loss and the influence of humans.

Mr Hocknull's scientific paper, Dragon's Paradise Lost: Palaeobiogeography, Evolution and Extinction of the Largest-ever Terrestrial Lizards (Varanidae), was published on-line today in PLoS ONE, the Public Library of Science's interactive open-access, peer-reviewed journal for scientific and medical research. The publication can be accessed at this link: http://dx.plos.org/10.1371/journal.pone.0007241.

Media Contact: Louise Sturgess 07 3842 9388 or 0417 741 710