Dating Fossils: Zircons are a Palaeontologist’s Best Friend

The Winton Formation is one of Australia’s most important fossils sites, hosting a dizzying array of unique fossils.  These include dinosaurs such as Australovenator, also known as “Banjo”, some of the world’s oldest flowers, and, most impressively, the world’s only fossilised dinosaur stampede!

Given the immense paleontological value of this site, you’d think scientists would be doing their best to date these fossils as accurately as possible, right?  Well…

Now, don’t get me wrong, researchers of the Winton Formation have made amazing strides in our understanding of central Queensland’s ancient ecosystems.  The Winton Formation preserves species that lived before, during and after the break-up of the supercontinent Gondwana.  This has afforded palaeontologists the unique ability to study the effects dramatic environmental changes on entire evolutionary linages, all contained within a single fossil site.  These scientists have literally written the book on eastern-Gondwanan dinosaur dispersion and evolutionary radiation.

So, What’s The Prob Bob?
Despite the obvious significance of this site, poor dating techniques have prevented scientists from recreating the entire global evolutionary picture of ancient species.  This is because the fossils have been dated using what is called “relative dating”, where fossil age is determined by comparing it to fossils and rocks that have already been dated.  This method only gives a “ballpark” figure, which generally has quite a high margin of uncertainty.

Currently, the most accurate dating technique involves zircons, a hardy mineral commonly found in continental volcanic rocks.  Zircons are like the Earth’s little black box recorder, and are dispersed throughout the Winton Formation – including many fossil beds.

The age of the youngest zircons found in a fossil bed gives the maximum age for all the fossils in that rock, because the rock containing the fossils cannot possibly be older than the volcanic rock (or lava) that sourced the sediments which formed the rock in the first place.

Zircon dating can be used to substantially reduce the expansive ballpark age ranges, and, in theory, allow the fossils of the Winton Formation to finally be correlated with their global counterparts.

Why Should I Care?
Poor or inaccurate dating of these fossils not only means they cannot be properly placed in an evolutionarily context, but it makes it incredibly hard to place them into any meaningful context on a global scale.  As a result, any collaborative work between Australia and other countries is pretty much impossible because our poor age constraints will skew their data.

This will not only limit the progression of research, but potentially stifle Australia’s ability to compete with the world in the field of palaeontology.

The Winton Formation is one of the only places on the planet that preserves fossils from before, during and after the break-up of a supercontinent.  Palaeontologists need to catch up!

Palaeontologists need to start using all the dating techniques available to them, to ensure valuable sites like the Winton Formation are given the scientific consideration they deserve.

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