Dinosaur hunters find 215-million-year-old ‘double root’ tooth and new species of Triassic creature resembling a large mouse
The oldest double-root tooth in the world and a new species of mammal have been discovered by palaeontologists.
The 215 million-year-old molar was found on the eastern coast of Greenland by Grzegorz Niedźwiecki from the Uppsala Univeristy in Sweden, along with Tomasz Sulej and Andrzej Wolniewicz from the Polish Academy of Sciences.
Wolniewicz posted on Twitter: “During the fieldwork, I remember Tomasz more-or-less seriously saying that we need to keep looking for fossils of early mammaliaforms, which was comparable with looking for a needle in a haystack.
“Well, guess what - no one other than Grzegorz Niedźwiecki found the needle!”
Niedźwiecki added: “I knew it was important from the moment I took this 20 mm specimen off the ground.”
What they found was a fossil that didn’t look that impressive at first – a less than 3cm-long broken piece of a lower jaw with most of the teeth missing.
However, a CT-scan revealed anatomical details that showed the finding was the earliest known example of dentary bone with two rows of cusps on molars and double-rooted teeth.
The bone belongs to a new early-diverging haramiyid species from the late Triassic around 215 million years ago, named Kalaallitkigun jenkinsi (Greenlandic for 'tooth from Greenland') by its discoverers.
The anatomical features place Kalaallitkigun jenkinsi as an intermediate between the mammals and the insectivorous morganucodontans, another type of mammaliaform.
It was a very small, shrew-like animal, probably covered with fur, the size of a large mouse. The teeth provide evidence to the changing feeding habits of the animals.
In this case, the animals were switching to a more omnivorous or herbivorous diet and the tooth crown was expanding laterally.
“The early evolution of mammals is a particularly interesting topic in evolutionary studies. This tiny jaw from Greenland shows us how complex mammalian teeth arose and why they appeared,” said Niedźwiedzki.
The biomechanical analysis that was carried out by the scientists proved that multi-rooted teeth are better able to withstand mechanical stresses, including those of upper and lower tooth contact during biting, compared to single-rooted teeth. Human teeth, for instance, have this characteristic.
The results of their research were recently published in the scientific journal PNAS.