A team of paleontologists studied Evolution of the canines from various excavations Dicinodonts, the distant relatives of modern mammals, which lived before the dinosaurs, about 270 to 201 million years ago, and were the first animals to be equipped with fangs.
The dysinodon had the appearance of a reptile, with beaks similar to those of turtles.
Since its discovery 176 years ago, one of its distinguishing features has been the pair of fangs that protrude from its upper jaws – in fact, The name dicynodont even means “dog teeth.”
Researchers Megan Whitney of Harvard University and Ken Angelcic, curator of the Field Museum in ChicagoThey wanted to know why dicynodont canines were called tusks without the formal requirements for it being in place.
Details of the study were published today in Proceedings of the Royal Society B.
Not all prominent teeth are technically canines. Only the composition of the teeth and growth patterns determine whether they are or not.
“For this job, we had to define canine, because it’s a surprisingly vague term.”Whitney Dice.
For a tooth to be a canine, it must extend beyond the mouth, continue to grow throughout the animal’s life, and, unlike the teeth of most mammals (ours included), must be covered in dentin in place of hard enamel.
Under these criteria, elephants, walruses, and pigs have tusks but ferrets, for example, do not, because although they sometimes protrude and do not stop growing, they have a strip of enamel at the front of the tooth.
Some dental treatment canines also did not seem to fit the definition of a canine: they were covered with enamel rather than dentin.
The different combination of teeth is an evolutionary strategy. Those with enamel – like those in humans – are more resistant than those in ivory, but they are unfavorable because they are difficult to repair: once they grow, if they are broken, there is no solution.
On the other hand, canines are less durable than our enameled teeth, but they grow constantly, even if they are damaged.
To study whether dicynodont canines really were canines, the researchers cut thin sheets of fossilized teeth from 19 specimens from ten different species and examined their structure.
They also used computerized tomography (CT) scans to examine how the teeth were attached to the skull and whether their roots showed evidence of continued growth.
They found that some of the dicynodont’s teeth were actually canines, while others, especially those of some early species, were just large teeth.
For Whitney, it was a surprising discovery: “I was hoping there might be a point in the family tree where all dysinodonts start having canines, so I found it surprising to see canines evolving in such a convergent way.”
“Dicynodont tusks can tell us a lot about the evolution of mammalian tusks in general”English dice.
“Dicynodonts were the most abundant and diverse vertebrates on Earth just before the time of the dinosaurs, and are famous for their ‘tusks’.”. The fact that only a few have real canines, and the rest have large teeth, is a beautiful example of evolution that we can document. We can see how the tusk is built.”says Brandon Peacock, curator of the Idaho Museum of Natural History.
The researchers believe the study, which shows the first known case of true canines, could help scientists better understand how evolution works.
With information from EFE.
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