Researchers discover an amazing connection between prehistoric dinosaurs and mammals of the teeth

Thin section of partial gorgonopsian canal under polar light. Services are prominent on the right hand side of this sample. Credit: Megan Whitney

When most people think of rough, blade-like teeth on prehistoric creatures they paint a picture Smilodon, better known as the toothed tiger. But in the world of dinosaurs, a theropod is famous for blade-like teeth with serrated cutting edges used for biting and tearing their prey. And until recently, the complex arrangement of figs that caused these frightening teeth was considered unique to those meat-eating dinosaurs.

In a paper published December 16 in Biology Letters, lead author Megan Whitney, a postdoctoral fellow in the Department of Organic and Microbial Biology, Harvard University, studied thin fossil chips of gorgonopsian teeth and found a complex arrangement similar to figs that performed the similar services to a steak knife in a theropod.

Gorgonopsians are a group of synapsids from mid-late Permian 270-252 million years ago. These animals, like other synapsids, are thought to be ahead of mammals and are within the line that ended mammals. “These animals were apex predators of their day and are characterized by the saber-like canine that can extend up to 13 cm in length,” Whitney said.

Previous studies of theropod dinosaurs have found a complex arrangement of figs made of both enamel and tooth forms that formed the rows on their teeth. This complex arrangement was considered unique to theropod dinosaurs. But no one had ever done a thin piece of gorgonopsian tooth before to examine the services.

You have my sharp teeth!

Full-toothed canine from gorgonopsian from Zambia. This sample includes both the crown (top) and root (bottom) of the tooth. Credit: Megan Whitney

Motivators, Whitney and co-authors combined their knowledge in paleohistology (study of microstructure of fossil skeletal figs) and studied thin sections of fossils from three synapsids from three different periods to theory about the structure of services in the group to prove this. . “It surprised us to find theropod-like services in gorgonopsians,” Whitney said. “We wanted to see how other carnivorous synapsids had performed their services, so we looked at an older synapsid [Dimetrodon] and younger mammalian synapsid [Smilodon]. “

Gorgonopsian, Dimetrodon, and Smilodon all synapsids and as theropods are the apex predators of their day and had serrated teeth, resembling a knife (i.e. ziphodonty). Dimetrodon one of the earliest synapsids in the Cisuralian period around 295 to 272 million years ago; Dimetrodon often described as a dinosaur. Smilodon lived in America during the Pleistocene era 250 million years ago to 10,000 years ago. “All of these animals fall on the mammalian line that is different from the dinosaur reptile line,” Whitney said. “In fact, these three animals are more connected to humans than to dinosaurs.”

Ph.D. focusing on the teeth of gorgonopsians and other mammalian precursors and so she examined the gorgonopsian samples collected from continuous, extensive fieldwork in Zambia where many of these animals are found. Co-authors Aaron LeBlanc, a graduate of the Department of Biological Sciences, University of Alberta, Ashley Reynolds, Ph.D. a candidate in the Department of Ecology and Evolutionary Biology, University of Toronto, and Kirsten Brink, an assistant professor in the Department of Geological Sciences, University of Manitoba, gained knowledge in the history of dentistry and the animals included in this study.

The thin sections revealed that the gorgonopsian acids are composed of full-package services made of both enamel and dentine, the same complex arrangement of figs that were previously given to theropod dinosaurs and were special respect for them. “What’s surprising is that these types of serrations in gorgonopsians are more similar to those of meat-eating dinosaurs from the Mesozoic period,” LeBlanc said. “It means that this particular type of cutting tooth first emerged in the line that led to mammals, only to develop independently in dinosaurs.”

You have my sharp teeth!

Both are large images of the services under polarized light. Gorgonopsian acids are made from both enamel (thinner, lighter on the right side) and dentine (thick cloth on the left) and intervertebral folds (a black structure in the middle that is a layer between the layers ). This special arrangement allows more serrations to be packed tightly around the tooth and makes each serration more resistant to wear. Credit: Megan Whitney

“The reality is that we only see this type of service growing in meat-eating animals,” said Brink. “The tiny microstructures hidden inside the teeth greatly benefit the tooth, strengthen the gums and help them last longer in the mouth, which in turn helps the animal to eat effectively. “

While gorgonopsians share this attraction with theropod dinosaurs, they certainly share more traits with other synapsids like Dimetrodon and people. “These animals came together on a similar morphology of dental servicing because of the functional benefits, not because they are close relatives,” Whitney said. “In this case, it may have something to do with the fact that animals were actually putting a lot of wear and tear on their teeth. And so independently they were able to create a service that is going to withstand the forces that are needed again to eat because eating is important. So there is a lot of choice working on teeth. “

Me, what sharp teeth

Gorgonopsian was the first animal with saber teeth. Their canines expanded up to 13 centimeters. Cliu: CCA 3.0 / Dmitry Dogdanov

Gorgonopsians were a diverse group with a body size ranging from a medium-sized dog to a bear and Whitney notes, although the samples had this type of morphology sampled, it is still possible that there is a mix of service types that would match the diversity of gorgonopsians.

Fossil evidence of a tumor in a 255-million-year-old mammal progenitor

Further information:
Controversial dental changes in the servicing of hypercarnivorous synapsids and dinosaurs, Biology Letters,… .1098 / rsbl.2020.0750

Presented by Harvard University

Citation: Researchers find amazing link between prehistoric dinosaurs and mammals of teeth (2020, December 15) on December 17, 2020 retrieved from teeth.html

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