Imaging technology has revolutionised palaeontology, allowing scientists to study fossils that are buried deep in the rock or too small to handle. Two recent studies I was involved with show some of the technology’s potential, including one that discovered a new dinosaur species that loomed over other carnivores it lived alongside hundreds of millions of years ago.
In the first study, my colleagues and I investigated an impression of a fossil jawbone that had been described in 1899 only as having come from a possible dinosaur. Because of its age (203 million years old), the specimen had added importance as, potentially, an unusually large early flesh-eating dinosaur.
Dinosaurs originated during the Triassic period, from 252–201 million years ago, but generally the flesh-eating forms remained under 3 metres in length and weighed no more than an alsatian dog. We knew the 1899 specimen, from the late Triassic near Cardiff in south Wales, showed portions of an ancient animal’s jaw and flesh-eating teeth, and could have come from an animal five metres or more in length.
The specimen had not been much studied since 1899 because it consisted only of impressions in the rock. At the time of discovery, the block had been split, revealing an impression of the inside and outside of the mandible, with 16 teeth and tooth sockets. But none of the original bone material remained.
Traditionally, palaeontologists would make a cast of the specimen using plaster or some flexible plastic, but such casting could damage the delicate fossil. So the specimen remained in storage in the museum for over a century.
We applied a new but simple method to acquire a 3D model called photogrammetry. This consists of taking numerous photographs of the two natural rock moulds and then stitching them together using 3D modelling software, a bit like the panorama function on many smartphones that can combine photographs of a wide vista.
The resulting 3D jaw can be viewed from all sides and rotated. That makes it much easier to study than the rock moulds.
The method caused no damage to the unique fossil specimen and can be shared with other scientists for further examination. In this case, the natural rock mould was highly detailed, retaining information on canals through the bone for blood vessels and nerves, and even the serrations on the cutting edges of the teeth.
We compared it with other dinosaur fossils and determined that it came from a dinosaur similar to Dilophosaurus from the early Jurassic period 201-174 million years ago, in the US. But it was 10 million years older and an entirely new genus and species.
We named it Newtonsaurus cambrensis after Edwin Tulley Newton who first studied it in 1899. The jaw suggests an animal originally 5-7 metres long, a large two-legged flesh-eater with grasping hands and powerful jaws.
In the second study, we scanned a tiny reptile skeleton, also from Triassic rocks. This one was found in Devon and was 40 million years older, at 243 million years old.
When it was found in 2015, Rob Coram, the collector, tried to clean up the tiny skeleton using traditional methods, removing grains of sand with a fine needle. However, the tiny size of the specimen, with a 1cm skull and three teeth per millimetre, made this impossible.
We first made a CT X-ray scan on a regular micro-CT scanner and made a detailed 3D reconstruction. The detail was not enough, though, so we then scanned it at the European synchrotron in Grenoble, France, so each tooth, and many other structures could be rendered in detail. A synchrotron makes an extremely intense beam of light that scientists use to study minute matter.
Rob Coram, Author provided (no reuse)
The scans and reconstruction tell us that this little reptile, which we named Agriodontosaurus, was an insect eater. It tussled with cockroach-like bugs as big as its head and crunched their cuticles with its broad, chisel-like teeth.
Virtual palaeontology
CT scanning has become ubiquitous in palaeontology, with hundreds of scanning machines installed in university and museum research departments.
In the case of the Agriodontosaurus, CT scans gave us clear views of the zones of compact and less compact bone as well as the attachments of the teeth.
Now 3D digital models let scientists look inside bones and shells, revealing hidden anatomical information. For example, several shelled organisms, such as ammonites and foraminifera, developed throughout their lives from a single shell chamber, coiling ever outward as they laid down new living chambers. The entire developmental history is there inside the adult shell and it can dissected out in the scans.
The digital models of fossils can also be used for functional experiments. For example, the mechanical properties of skulls can be analysed, modelling where an animal’s jaw and skull are hinged, reconstruct its muscles, and calculate its bite forces. This tells us that Tyrannosaurus rex could exert a bite force of as much as 50,000 Newtons, equivalent to a force of 5 tonnes.
Another approach, finite element analysis, allows palaeontologists to test the responses of a skeleton or skull to compression and tension. These bioengineering studies have shown, for instance, that predatory dinosaurs generally were not good at tussling with their prey by twisting and turning – they mainly concentrated on straight up-and-down bites.
This is the new world of virtual palaeontology. Let’s see where it takes us.
