Location: Queensland, Australia
Age: 25 million years to present
Taphonomy is the process of fossilisation, from death of an organism to burial and eventual discovery. At Riversleigh, the limestone caves and channels provided an ideal resting place for the animals. Many of the animals lived within the caves and so when they died, they fell to the floor and would have been covered by cave deposits. The other animals may have died outside the cave system and been washed in to them by rivers which crossed the area. The limestone pavement is dangerous to walk across because of large chasms and weak cave roofs. Many animals may have fallen to their deaths on their grazing and hunting movements.
Once the animals had died, many of their bones became disarticulated and broken up in the river currents. However some animals such as the Thylacine were covered quickly and although its flesh quickly decayed, their bones are preserved exceptionally well. Quick burial allows some bones to stay articulated such as some of the bats.
The rivers that carried the animals and covered them are full of dissolved carbonate from the limestone. This water affected the bones by helping in the preservation and made them stronger. Once the flesh had decayed, the river helped in the fossilisation and eventually buried them in layers of protective limestone. The hard deposits of limestone have helped make discovering the bones more easy. Erosion of the softer rock surrounding the bones has exposed the harder bones.
References and links
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