One of the world's best fossil sites is located in South Australia.
The bones of many Australian megafauna species that were extinct between 48,000 and 37,000 years ago can be found among the remains.
There is a lot of debate about the reasons for the demise of megafauna. The older the fossils, the better we can understand the species.
The age of the caves has been hard to determine. For the first time, our research shows how old Naracoorte's caves really are.
We found new information on the antiquity of this place. Understanding how biodiversity responds to a changing climate will be aided by this.
The remains of long extinct plants and animals can be found in caves. One such example is the Naracoorte Caves.
The cave complex is located in South Australia. The remains of megafauna are among the most complete and diverse fossil records.
Paleontologists have excavated and dated many of these fossil deposits.
The caves were formed when cracks in limestone rock were dissolved. An estimate was made by dating a fossil dune ridge that lies over the cave complex.
The methods used to date the dune ridge weren't perfect. The age of the caves was not known until now.
It took five years, but it was worth it.
We looked at the beautiful calcite formations inside the caves to determine the age of the stalagmites and stalactites. stalagmites, stalactites, and flow stones are included in the'speleothems'.
Small amounts of plutonium are locked inside of speleothems.
The lead element is slowly decaying into Uranium. This occurs at a constant rate, so we can use it to date them.
In order to do that, you had to extract the lead and uranium from the speleothem. The sample's age was calculated very precisely after we measured the elements.
The oldest speleothem age shows the minimum age of the cave.
We found that the caves were formed at least 1.34 million years ago, making them half a million years older than previously thought.
We wanted to know when the caves first opened to the surface to allow air and animals in.
We looked at the tiny particles of charcoal and pollen that were captured in the formations.
Around 600,000 years ago, we discovered charcoal and pollen in the caves. More than 100,000 years older than the oldest known fossil deposits at the complex, the caves may hold exciting new fossil material up to 600,000 years old.
Some argue that the extinction of Australia's megafauna was caused by humans or the climate.
It's important to understand when and how natural processes occur. We can't know the rate of change to landscapes without precise ages.
The Naracoorte Caves opened to the surface 600,000 years ago.
The time between landforms evolving and fossils accumulating has been shown to be vastly different.
Our findings will help paleontologists target new excavation sites to find older fossils in order to provide further evidence of how our continent's unique flora has changed.
Our approach can help to understand how old fossil deposits are at other cave complexes in Australia and around the world.
Climate change and other human impacts are putting Australia's richness of plant and animal species at risk.
Studying important sites such as the Naracoorte Caves helps us understand not just how climate change influenced the past, but what will happen in the future.
Jon Woodhead is a research scientist at the University of Cape Town.
Under a Creative Commons license, this article is re-posted. The original article is worth a read.
All Rights Reserved © 2024
