Australasian Science 11

and giant lizards actually overlapped in

time – until now at least.

Prior to our new study, the youngest

accepted records for lizards like Megalania

were around 80,000 years old. For Komodo

dragons they are closer to 300,000 years. In

our new study on the Colosseum Chamber

specimen, we were able to show, deinitely

for the irst time, that humans and the giant

monitors overlapped in time. We essentially

extended the younger-end of the timeframe

of the giant lizards of Australia by around

30,000 years. Our study has been published

in Quaternary Science Reviews(tinyurl.com/

z6cjh32).

So what does that mean for the lizards?

Did humans wipe them out? Did the lizards

prey on people? It’s hard to say at this stage,

but so far we do not have any palaeonto-

logical or archaeological evidence that they

actively encountered each other. We’d be

surprised if they didn’t though.

We Need More Data
One thing that’s yet to be deinitely
answered is exactly when the giant lizards
became extinct. Our study statistically
modelled the possible timing of the extinc-
tion event using all of the reliable dates avail-
able for the extinct lizards. The models that
we applied are well-established and are the
exact same ones that have been used to esti-
mate when other famous organisms, like the
Dodo, became extinct.
The modelling results showed something
that, in a way, was not overly surprising to
us: every model suggested that the giant
monitors did not go extinct but are still
living in Australia today!
We are not arguing that either the
Komodo dragon or Megalania are still
kicking around on the continent, but our
analyses highlight just how patchy the existing datasets are for
the extinct species – not just the monitor lizards but all
Australian megafauna. With the addition of the Colosseum
Chamber specimen, we now have only seven reliably dated
records for giant lizards. Worryingly, this is one of the most
extensively dated records among all of the Australian megafauna.
It’s just not possible to reliably model megafaunal extinctions
with such scant datasets, but we are getting closer.

We critically need more reliably dated records to test the

leading extinction hypotheses properly. With more research, the

temporal datasets for all of the extinct megafauna, not just the

giant lizards, can be better developed. Only then will we really

be able to establish a strong understanding of what happened

to Australia’s Ice Age megafauna.

Gilbert Price is a vertebrate palaeontologist in the School of Earth Sciences at The University

of Queensland. You can read his science blog at http://www.diprotodon.com.

APRIL 2016|| 23

Credit: Bryan Fry/Gilbert Price

An osteoderm from the giant Colosseum Chamber monitor lizard. Credit: Gilbert Price

A Komodo dragon and (inset) schematic diagram depicting osteoderms under scales.