Sur can be found in the teeth of primitive dinosaurs and mammals

Gorgonopsyan were the first clogged animals. Their dogs spread up to 13 centimeters. Credit: CCA 3.0 / Dmitry Dogdanov

When most people think of cruel, mouth-like teeth on prehistoric creatures that depict Smilodon, better known as the amber-toothed tiger. But in the world of dinosaurs, troopods are known for having beak-like teeth with toothed edges that are used to bite or tear their prey. And until recently, the intricate arrangement of tissues that produced these horrible teeth was considered unique to these carnivorous dinosaurs.

2020 In a work published on December 16 Biology lettersMegan Whitney, a graduate student in the Department of Organic Evolutionary Biology at Harvard University, studied thin fossils of Gorgonopsis teeth and discovered intricate tissue-like arrangements that yielded similar divisions with a steak knife.

Gorgonopsian Canine Scan:

A thin section of a partial gorgonopsis dog in polarized light. The divisions are obvious on the right side of this sample. Credit: Megan Whitney

The Gorgonopsians are a group of synapses from medieval Permia 270-252 million years ago. These animals, like other synapses, are considered to be the ancestors of mammals and belong to the lineage that eventually gave birth to mammals. “These animals were the highest predators of their time, characterized by their larval dog, which could grow up to 13 cm in length,” said Whitney.

Previous studies of tropod dinosaurs have revealed a complex arrangement of both enamel and denture tissues that make up the teeth. This intricate arrangement was considered unique to troopod dinosaurs. But no one has ever made a thin section of a gorgonopsis tooth to check for dentition.

Gorgonopsian Saber Toothed Canine:

A complete amber-toothed dog from Sa Ambia Gorgonopsyants. This pattern includes both the crown of the tooth (top) and the root (bottom). Credit: Megan Whitney

Inspired by Whitney, the co-authors combined their experience in paleohistology (a study of the microstructure of fossilized skeletal tissues) to study thin sections of fossils from three synapses of three different periods to test the structure of sections in this group. “We were surprised to find similar divisions of troopods in the Gorgonopsis,” Whitney said. “We wanted to see how other carnivorous synapses made their divisions, so we looked at an older synapsid. [Dimetrodon] և Younger, mammalian synapses [Smilodon

Gorgonopsyan, Dimetrodone, և: Smilodon they are all synapses; they are like predators of astopods; they have toothed teeth (ie, zipodontia). Dimetrodone It is one of the earliest synapses among the Sisuralians about 295 to 272 million years ago. Dimetrodone often mistakenly described as a dinosaur. Smilodon lived in America during the Pleistocene 2.5 million to 10,000 years ago. “All of these animals fall along the line of mammals, which is different from the line of reptiles with dinosaurs,” said Whitney. “In fact, these three animals are more closely related to humans than to dinosaurs.”

Whitney’s PhD focused on the teeth of the Gorgonopsis, the other ancestor of mammals, so he studied the Gorgonopsis specimens collected from the current, extensive fieldwork in the amb abyss where many of these animals are found. Co-authors Aaron LeBlanc, PhD in Biology, Ashley Reynolds, PhD in Ecology and Evolutionary Biology

The thin sections showed that the gorgonopsis chains were made up of tightly wrapped dentures, the same intricate arrangement of tissues previously attributed to tropod dinosaurs that were considered unique to them. What ‘s remarkable is that among the Gorgonopsis, the species of teeth are more like carnivorous dinosaurs. Mesozoyan the era, ”LeBlanc said. “This means that this unique type of cutting tooth first developed in the mammalian lineage, but later evolved on its own in dinosaurs.”

“The fact that we see only this type of dentition developing in carnivores is possible,” Brink said. “The small microstructures hidden inside the teeth give the tooth a significant advantage by strengthening the dentures, helping them stay in the mouth longer, which in turn helps the animal to eat more efficiently.”

Gorgonops liturgies enlarged

Both are magnified images of dentures exposed to light. The gorgonopsis denture is made of both enamel (thinner, lighter tissue to the right) and toothpick (denser tissue to the left) և interdental fold (black central structure that folds between the incisions). This feature allows the teeth to be tightly packed along the length of the tooth և each denture is more resistant to wear. Credit: Megan Whitney

Although Gorgonopsis share this trait with tropod dinosaurs, they actually have more characteristics with other synapses, such as Dimetrodone և People. “These animals matched their tooth-like morphology because of their functional benefits, not because they were closely related,” Whitney said. “In this case, it probably has to do with the fact that the animals really wore their teeth a lot. And so they were able to independently form a dentition that was going to withstand the repetitive forces needed to eat because eating is important. So there are a lot of choices that work on the teeth. ”

The Gorgonopsians were a diverse group of body sizes ranging from medium-sized dogs to bears.

Reference. “MR Whitney, ARH LeBlanc, AR Reynolds, KS Brink, December 15, 2020,” Convergent Dental Adaptations in the Synapses of Hypertensive Animals և Dinosaur Dental Teeth ” Biology letters,
DOI: 10.1098 / rsbl.2020.0750:

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