Australasian Science: Australia's authority on science since 1938

The Rise of High-Tech Palaeontology

By John Long

High-tech scanners now enable palaeontologists to gain new insights from significant fossils embedded in solid rock.

For many years palaeontologists had a fairly simple way of working. Many of us used to dig up fossils, photograph and draw them, describe them and publish a paper about them. What we could see was really all we could study.

This approach has changed dramatically in the past decade as high technology imaging now allows us to mine fossils for new layers of information. This has caused a revolution in the study of palaeontology as we can now apply various methods to image any part of a fossil, even if it’s still enclosed inside rock.

In 1980 during my Honours year I thought it was pretty radical to use a high-powered engineering X-ray machine to image fish fossils that were still in rock. This gave us a hazy but useful 2D image of the unexposed part of the fossil inside the rock, and worked well as long as the rock layer wasn’t too thick (e.g. less than 3 cm).

Then, in the early 2000s, micro-CT scanners arrived on the scene. The fossil spins around in the scanner and the X-rays make hundreds of slices through it, and these are digitally stitched together into a high-resolution 3D image. Using segmentation software we can then identify each cross-section of the series and colour the different bony elements to help identify the parts in 3D. Other software like the feeeware Drishti available from the Australian National University’s Vizlab allows us to see inside the rock or the fossil and make an image showing much of the internal structure – even the cellular details of the bone or teeth – without the time-consuming task of segmentation.

The advent of synchrotron technology has now enabled us to ramp up the whole micro-CT approach to powerful new levels. Machines like the Grenoble Synchrotron in France shoot high-powered beams through rocks containing fossils (say up to 10 cm thick). The Australian Synchrotron can do similar tasks, as I recently found out last month using its new Imaging and Medical Beamline with great success. A series of amazing papers has been produced over the past decade or so using this method, which is becoming almost standard practice now the more machines are becoming accessible to researchers.

So what’s next? The main limiting factor of micro-CT and synchrotrons is the density of rock enclosing the fossils, so important specimens inside relatively thick rocks are still the main problem to image. Enter the new Dingo neutron beam at the Australian National Science and Technology Organisation in Lucas Heights. Dr Joe Bleviit has shown me preliminary results of trials of this amazing machine on a number of fossils. It can image through solid rock up to about 20 cm thick. Using a concentrated beam of neutrons, it images different compositional elements in the rock. As bone has a different composition to, say, limestone or shale, the bone shows up very clearly with resolution down to 30 µm slices. This means we now have a powerful new tool to go back and test many significant fossils to find the missing bits of the information we need to understand important evolutionary transitions.

The game has now changing rapidly. Who knows what’s coming next? I can assure you it’s an exciting time to be a palaeontologist.

John Long is Strategic Professor in Palaeontology at Flinders University, and current President of the Society of Vertebrate Paleontology.