Koala - ancient companion of the gum tree
Imagine … catching sight of a fossilised creature that hasn't seen
the light of day for 20 million years. Your heart's pounding,
your spine's tingling as you stare in delighted silence, trying to
identify the extraordinary animal from a lost world. Unwrapping
gifts from prehistoric Queensland is the everyday for Senior Preparator
Al Rackham and Volunteer Jo Riddington at the Riversleigh Fossil Centre's
laboratory in Mount Isa.
The lab located at Outback at Isa, Mount Isa's Tourism Centre, stopped
extracting fossils in late 2009, only returning to the task in late 2016.
We don't dwell on the reasons why this happened but rather concentrate on
the 'parade of life' that now tumbles from the ancient limestones.
Every day there is an extreme buzz of excitement as Al and Jo extract
specimens from limestone collected many years ago, from the site known as
'Two Trees' in the Riversleigh World Heritage area near Adels Grove.
Recently, amongst the emerging biological paraphernalia of lung
fish jaws, turtle shells, snake vertebrae and cat fish barbs, something
even more surprising protruded. On its unexpected path to
immortality, the pearly molar of a marsupial mammal appeared.
Uncertain from what doomed animal it belonged, Al showed it to visiting
Palaeontologist, Professor Mike Archer. The Professor took a very
educated guess that this 'little furry' may be from an extinct species of
koala, but to be sure we will send it off to Sydney for further analysis.
It is thought that koalas (who were smaller than their modern
counterparts) were rare in Australia's ancient rainforest landscape.
Singling out eucalypts as their special resource, the ancestral koala
developed a dependency that persists to this day. Eucalypts thrive in
poor soil, so as the rainforest rapidly deteriorated in the dryer
climate, the gums with their rare dinner guests persisted and flourished
in expanding areas of nutrient impoverished soils.
It is exciting to be a part of Riversleigh's prehistoric menagerie where
the past unfolds and presents a jigsaw puzzle of hundreds of tiny bits
and pieces. Exquisitely preserved species from the Riversleigh fossil
fields in Northern Australia tell the story of the 'Australia Marsupial
Arc'. When the rest of the world's mammals were developing into
elephants, tigers, bears and horses, we were developing our flesh eating
kangaroos; rhinoceros sized wombats, marsupial lions and fuzzy little