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Komodo dragons bite prey with iron-tipped teeth
The world’s largest living lizard has a thin coating of iron on its teeth.
This helps the Komodo dragon to keep its teeth sharp, allowing the venomous predator to target a wide range of animal prey.
Orange lines on the Komodo dragon’s teeth have revealed how the reptile maintains its powerful bite.
New research reveals that iron-rich enamel along the serrated edges of the Komodo dragon’s teeth strengthens the teeth and slows down wear. The orange colour this causes remains on the teeth long after death, suggesting this feature could also be found in extinct species.
One strong candidate for these strengthened teeth are carnivorous dinosaurs like Tyrannosaurus rex. As they had similarly serrated teeth to the Komodo dragon, the researchers think it possible that they might also evolved iron tips.
While the scientists are yet to find evidence for this, Dr Aaron LeBlanc, the lead author of the study, says that the chemistry of the fossils might hold some clues.
“With further analysis of the Komodo dragon teeth we may be able to find other markers in the iron coating that aren’t changed during fossilisation,” Aaron explains. “With markers like that we would know with certainty whether dinosaurs also had iron-coated teeth and have a greater understanding of these ferocious predators.”
Dr David Hone is a carnivorous dinosaur expert at Queen Mary, University of London, and was not involved with the research.
“Tyrannosaurs have super thick and strong teeth, with various adaptations to stop them breaking,” David adds. “So, it's not a huge surprise that they have been able to develop other features to strengthen them.”
“However, now we know iron-tipped teeth are present in one reptile, it's at least possible it evolved in others too. It’s definitely something to look out for in the future.”
The findings of the study were published in the journal Nature Ecology & Evolution.
The iron deposits form a distinct orange layer around the cutting edges of the tooth. © Dr Aaron LeBlanc, King’s College London.
Where do serrated teeth come from?
Serrated, or ziphodont, teeth are often a sign that an animal is an apex predator. While blade-shaped teeth are well-suited to tearing, the serrations help to provide extra force as they cut into the flesh of prey.
Some of the most advanced serrated teeth have a complicated arrangement of dentine and enamel to form the individual serrations, known as denticles, along the teeth. Between each denticle is a minute fold that protects the teeth from cracking, even under intense pressure.
These folds first appeared over 255 million years ago in an ancient group of mammals known as gorgonopsians. These animals are considered to be the first sabre-tooths, and it is thought that these folds would have protected the animals’ large teeth from breaking when they delivered powerful bites to take down prey.
Millions of years later, the same adaptations appear in the jaws of tyrannosaurs and other theropod dinosaurs. This is an example of convergent evolution, with the folds evolving independently in both linages to stop the bone-crushing bites from harming the predator itself.
Today, monitor lizards like the Komodo dragon are among the only reptiles with serrated teeth. This makes them a useful animal to study when researchers are looking to understand how the teeth of carnivorous dinosaurs worked.
Tyrannosaurs also have serrated teeth, but it's uncertain whether or not they had iron deposits as well. © The Trustees of the Natural History Museum, London.
From dragons to dinosaurs
After investigating the teeth from a variety of different Komodo dragons, including some from the Natural History Museum’s collections, the team noticed that the serrated edges all had a distinctive orange colour.
The colour is the result of high concentrations of iron in the teeth, something that’s only been seen in a few animals such as beavers, salamanders and certain fish. While in beavers the iron is known to help harden the teeth, its purpose in other animals is currently unclear.
By looking at teeth from museums and zoos, the researchers found that other monitor lizards and some crocodiles also all had iron in their teeth. However, it was only in the Komodo dragon that the iron was concentrated enough around the tips and serrations of the teeth that it became visible.
While it’s possible that theropod dinosaurs might have similarly iron-tipped teeth, the researchers’ findings are currently inconclusive.
“Unfortunately, using the technology we have at the moment we can’t see whether fossilised dinosaur teeth had high levels of iron or not,” Aaron says. “We think that the chemical changes which take place during the fossilisation process obscure how much iron was present to start with.”
Instead, it looks like these teeth of big carnivorous dinosaurs had a more complex structure, with tyrannosaur serrations made up of a tough material known as wavy enamel. This has previously only been found in some herbivorous dinosaurs where the structure helped to prevent the teeth from cracking while chewing through tough vegetation.
Despite the setback in looking for iron in larger dinosaur teeth, the team are hopeful that smaller dinosaurs with thinner enamel might provide the evidence they are looking for. If they do, it could help to explain why these reptiles rose to become apex predators millions of years ago.
