Meat-eating dinosaur could replace its teeth as fast as SHARKS — regrowing them every two months, study reveals
- Experts studied the teeth of the 70 million-year-old dinosaur Majungasaurus
- They compared their findings with those from Allosaurus and Ceratosaurus
- Majungasaurus replaced teeth 13 times faster than other prehistoric carnivores
- Researchers believe this was needed because it wore its teeth down on bones
A meat-eating dinosaur could replace its teeth as fast as a present day shark — growing replacement gnashers every two months, a study has found.
Researchers studied the teeth of the Majungasaurus, which lived in what is now Madagascar around some 70 million years ago.
Its tooth replacement rate was up to 13 times that of other prehistoric carnivores — putting it in same league as sharks and big, herbivorous dinosaurs.
Experts believe that the dinosaur species developed rapid-fire tooth growth because it wore down its teeth by gnawing on bones.
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A meat-eating dinosaur (Majungasaurus, right) could replace its teeth as fast as a present day shark — growing replacement gnashers every two months, a study has found. Left, the skull and teeth of a Ceratosaurus, which researchers analysed for comparison
‘There is independent evidence for this in the form of scratches and gouges that match the spacing and size of their teeth on a variety of bones – bones from animals that would have been their prey,’ said Adelphi University biologist Michael D’Emic.
He noted that today’s animals — including rodents, for example — gnaw on bones.
‘It’s a way for them to ingest certain nutrients. It also requires exceptionally strong teeth – but Majungasaurus did not have those,’ Professor D’Emic added.
‘That’s our working hypothesis for why they had such elevated rates of replacement.’
The researchers also examined two other species of predatory dinosaur — the Allosaurus and Ceratosaurus — enabling them to consider tooth growth patterns more broadly.
In particular, Dr D’Emic teamed up with Ohio University anatomy expert Patrick O’Connor in order to examine microscopic growth lines in the teeth taken from a fossil collection.
He likened these growth lines to tree rings, albeit ones that are deposited daily, instead of but once a year.
Researchers studied the teeth of the Majungasaurus, which lived in what is now Madagascar around some 70 million years ago
Majungasaurus’ tooth replacement rate was up to thirteen times that of other prehistoric carnivores — putting it in same league as sharks and big, herbivorous dinosaurs. Pictured, CT-scan images (top) and microscopic close-ups of teeth showing growth lines for Majungasaurus (left), Ceratosaurus (centre) and Allosaurus (right)
The team also CT scanned intact jaws to visualise teeth growing deep inside the bones.
This allowed them to estimate how quickly the teeth would grow in a large number of individual jaws, so they could cross-check their results.
‘This project addresses yet another aspect of the biology of Majungasaurus, and predatory dinosaurs more generally,’ he added.
‘It heralds the next phase of research based on recent field discoveries.’
The full findings of the study were published in the journal PLOS ONE.
WHY DID THE DINOSAURS GO EXTINCT?
Dinosaurs ruled and dominated Earth around 66 million years ago, before they suddenly went extinct.
The Cretaceous-Tertiary extinction event is the name given to this mass extinction.
It was believed for many years that the changing climate destroyed the food chain of the huge reptiles.
In the 1980s, paleontologists discovered a layer of iridium.
This is an element that is rare on Earth but is found in vast quantities in space.
When this was dated, it coincided precisely with when the dinosaurs disappeared from the fossil record.
A decade later, scientists uncovered the massive Chicxulub Crater at the tip of Mexico’s Yucatán Peninsula, which dates to the period in question.
Scientific consensus now says that these two factors are linked and they were both probably caused by an enormous asteroid crashing to Earth.
With the projected size and impact velocity, the collision would have caused an enormous shock-wave and likely triggered seismic activity.
The fallout would have created plumes of ash that likely covered all of the planet and made it impossible for dinosaurs to survive.
Other animals and plant species had a shorter time-span between generations which allowed them to survive.
There are several other theories as to what caused the demise of the famous animals.
One early theory was that small mammals ate dinosaur eggs and another proposes that toxic angiosperms (flowering plants) killed them off.