How T. rex kept its teeth sharp
A group of carnivorous dinosaurs have been found to have much more complex teeth than previously expected.
Known as theropods, this group includes the most well known of dinosaurs - Tyrannosaurus rex - as well as several other, equally vicious species, all of which dominated the food chain in different periods.
Kirstin Brink and researchers from the University of Toronto cut open fossilised teeth from eight different species of theropod.
The cut surfaces were studied using an electron microscope, which revealed a surprising level of complexity.
On the outside, the teeth have large serrations - a series of bumps to help slice through flesh, like those you would find on a steak knife.
Normally, these would cause the teeth to weaken and wear away over time, which would leave the animal unable to feed.
To counteract this, theropods evolved unique arrangements of the two main tissues that make up teeth, dentine and enamel, to strengthen each serration and prevent erosion.
Armed with this dental adaptation, the teeth maintained their flesh-tearing properties for much longer, helping the theropods to stay at the top of the food chain.
Tooth structures like these had not previously been seen in meat-eating dinosaurs, although they are present in the teeth of the present-day Komodo dragon, which has a feeding pattern similar to its theropod ancestors.
Such sophistication was a big surprise. Herbivores, animals that eat exclusively plants, often have well-developed teeth, as chewing plant matter can otherwise cause very rapid dental erosion. However, meat is far softer and easier to chew, and so a much simpler tooth construction was expected.
Brink's study, published in the journal Scientific Reports, also investigated how these structures had developed.
Unlike us, reptiles have a constant cycle of teeth, with a 'spare set' forming in their gums at all times, getting ready to replace the ones that are currently being used when needed.
By performing the same analysis on these unused teeth in the gums, researchers found the exact same dentine structures as in the used teeth, disproving previous theories that the structures were caused by the stresses of feeding such as crunching through bones.
There are still many more types of Theropod that are yet to be investigated, providing an obvious future step for scientists. However, more intriguingly, there is also potential to investigate the teeth of early birds, as they too have been found to have serrations, used for similar meat-tearing purposes.