Australasian Science 11

The earliest Australians could have avoided the waterways
if they didn’t want to encounter this freshwater giant, but there
was no getting away from crocodiles altogether. Quinkana,
another Ice Age croc, was slightly smaller in size than Pallim-
narchusbut what made it unique was that it was land-based, and
could spend a long time away from sources of permanent water.
In terms of snakes, the biggest by far was Wonambi. With
a girth of 80 cm and length around 6 metres, this 250 kg pred-
ator far outweighed any of the modern massive snakes like the
boa constrictor and anaconda.
But among the scariest and most ferocious Australian Ice
Age predators were the giant monitor lizards. When the irst
modern humans island-hopped through South-East Asia en
route to Australia, they would have gained a feel for what life
was like living among big lizards like the Komodo dragon, a
species that is today restricted to only a handful of islands in the
Indonesian archipelago. But what greeted them on the other side
of their marine journey was a big lizard guild unlike anything
that they had experienced before.
It may have been a surprise that, despite the treacherous sea
crossing, Komodo dragons had already beaten them to the
punch and were already established on the continent. In fact,
the oldest fossil records of Komodo dragons in Australia date
all the way back to the Pliocene, some 3.5 million years ago. It
seems likely that Komodos actually evolved in Australia before
moving northwards.
The largest monitor lizard was by far the giant Megalania
(Varanus priscus). At 5–6 metres in length and weighing
300–500 kg, Megalania was the biggest lizard that ever existed,
anywhere and at any time, in the history of the planet. Mega-
lania had a huge distribution too, from the north-east and
central regions all the way down to south-eastern Australia –
and just about everywhere in between.
To top all that, another massive monitor
lizard, intermediate in size between Megalania
and the Komodo dragon, has also been
reported from central Australian fossil
deposits, but this has not yet been formally
described in the scientiic literature.
Some of the big questions then are what
was the nature of the interaction between the
earliest people and these predatory beasts? Did
humans regularly end up on the dinner plate
of a Megalania? Or was it the other way
around? When did the giants go extinct, and
how?
There are a couple of ways to try to answer
these important questions, but one of the most
obvious things to do irst is to determine the
age of the megafauna fossils and any associ-

ated archaeology. If you can at least place humans and the

extinct predators in the same place at the same time, the

hypotheses surrounding their extinction can only then be prop-

erly tested.

A Chance Discovery

Over the past 10–15 years, my research team has been exploring

the Ice Age fossil record around the Rockhampton area along

the central coast of Queensland. We had already discovered

some really amazing fossil sites that showed huge habitat changes

and extinctions of various species, but most of these records

dated to more than 300,000 years ago, long before the irst

humans ever irst stepped onto the continent.

One of the fossil sites that we’ve been really interested in is

Colosseum Chamber, which is part of an extensive cave system

at the Capricorn Caves tourist park, just north of the city. This

particular deposit is around 2 metres deep, and is incredibly

rich in fossil vertebrate remains.

If you have ever had the chance to see the cave, you’d ask

why we would even be there looking for megafauna. However,

big animals were not our target. Most of the fossils in the deposit

are tiny, and not “mega” in any kind of way. They belong to

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Australia’s Ice Age megafauna: Diprotodon, giant short-faced

kangaroo, marsupial lion and Megalania. Credit: Gilbert Price

Excavations at Colosseum Chamber. Credit: Gilbert Price