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The sensitive human teeth interior may have come from a seemingly unlikely place: sensory fabric for fish that sailed in the Ocean of the Earth 465 million years ago.
Although our teeth are covered with a solid enamel, it is a dental – the inner layer of the tooth responsible for carrying the sensory information to the nerves – it responds to severe bite, pain or changes such as extraordinary cold or sweetness.
In an attempt to determine the origin of teeth, one of many researchers, over the years in question, was that teeth could develop from ancient fish armored exoskeletons. However, the true purpose of the structures, called odontodes, was unclear.
Now a new study and 3D fossil scanning has given evidence that external bumps were dentin, which probably helped the fish understand their environment. Scientists reported conclusions on Wednesday in Nature magazine.
“With these sensitive tissues involved, perhaps when he contradicted to feel that pressure, or maybe he may feel when the water became too cold and had to swim elsewhere,” said the leader of the study dr. Yara Harid, Email of the Chicago Department of Biology and Anatomy In the letter.
During the analysis, the team also revealed the similarities of “odontodes” and properties called Sensilla, which exist as sensory organs in modern animals such as crab and shrimp, and can be found in fossil invertebrates. The development of the odontods in fish that are vertebrates and the aging grandparents who are invertebrates are a great example of evolutionary rapprochement – when similar properties develop in independently different animal groups, Hardy said.
“This jaw fish and aglaspidide arthropods (extinct maritime arthropods) have a particularly distant common common ancestor, who probably did not have solid parts,” Harid said. “We know that vertebrates and arthropods have developed independently in solid parts and amazingly, they independently created similar sensory mechanisms integrated into their hard skeleton.”
Although the arthropods retained their sensory, the Odontodes seems to be direct animal dental precursors.
As researchers compared Sensyl and Odontods, they also reached another conclusion: one species, once considered ancient fish, were actually arthropods.
Search of the oldest vertebrates
The original goal of Hariid was to solve the secret of the oldest vertebrate animals that exist fossil records. She appealed to the museums across the country and asked if she could read from the fossil specimens they had since Camria, 540 million years ago to 485 million years ago.
She then settled in the Almighty in Argonne National Laboratory, where she used her advanced photon source to capture high -resolution computer tomography or CT scans.
“It was a night at the particle accelerator; it was fun,” Hariid said.
Discharging a teeth reminiscent of the Odontode structure from the Sockouth Catfish Fish shows nerves (green) that allows you to transmit sensory information from Odontode to the nervous system. – Yara Harid/Chicago University
At first glance, the fossil of the creature, called Anatolepe, looked like vertebrate fish – and in fact the previous 1996 Studies found it as one. Hariid and her colleagues noted that there were several couples filled with material that seemed to be denial.
“We were high with each other, for example,” Oh God, we have finally done it, “Hardy said. “It would have been the very first teeth similar structure of caddle vertebrate tissue. So we were very excited when we saw the signal signs that looked like a denial.”
To confirm their discovery, the team compared scans to other ancient fossils scans, as well as modern crabs, snails, beetles, sharks, boletus and even miniature sockouth catfish, which Hardy raised.
These comparisons have shown that Anatolepen was more reminiscent of arthropod fossils, including one of the Milwaukee Public Museum. And what the team thought that the dentine tubules were actually more similar to Sensilla.
However, during the scan, they found dentin -containing odontods in ancient fish such as Eriptychius and Astraspis.
The confusion due to the true nature of Anatolepe was due to the fragmentary nature of the fossils. According to Harid, the most detailed pieces are only about 3 millimeters (0.1 inch), which proved to be a challenge for comparable research dependent on the external image.
CT scanning shows the tooth on the cat. These tooth -like structures are connected to the nervous system. – Yara Harid/Chicago University
However, the new scan she made allowed a 3D look at the fossils that reveal their inner anatomy.
“It shows that ‘teeth’ can also be sensitive even when they are not in the mouth,” Hardy said. “So these fish have sensitive armor. These arthropods contain sensitive armor. This explains the confusion with these early Cambria animals. People thought it was the earliest vertebrate, but it was actually arthropods. “
The most advanced modern image used in the study resolves discussions on “Anatolepe,” said Dr. Richard Derene, Postcorative Researcher in the Netherlands, Natural Biodiversity Center. Derene did not participate in new research.
“(The authors of the study) use the most advanced methods of obtaining modern image to resolve this issue by collecting an impressive set of comparative data so that Anatolepe is not actually vertebrates,” Derene stated in the letter.
Armor against elements
Armored jaw fish such as “Astraspis” and “Eriptychius”, and ancient arthropods such as Anatolepe, existed in dirty shallow seas of the Order, which had occurred in 485.4-443.8 million years ago.
Other contemporaries of these animals covered large cephalkers such as giant squid, as well as huge sea scorpions. Properties such as Odontodes and Sensilla would help fishing and arthropods to distinguish predators from prey.
This illustration of the artist portrays that Astrasspis attacked the mewicter of the sea bat in dark shallow waters. The glow of animal interacting exoskeletons shows how both of them would have felt the world around them. – Brian Engh/Living Reproductions
“When you think of such an early animal floating on armor, it has to feel the world. It was a rather intense predatory environment and the ability to feel the qualities of the water around them would have been very important,” said senior study author dr. Neil Shubin, a professor of exclusive service at Robert R. Baineley, a University of Biology and Anatomy of the body at Chicago University. “So here we see that invertebrates with armor like horseshoe crabs also have to feel the world, and it happens that they hit the same solution.”
Several modern fish have odontods, and sharks, skates and some catfish are covered with small teeth called teeth that make their skin feel like sandpaper, Hardy said.
Hariyd’s examined the tissues of catfish she collected and realized that their teeth particles are connected to the nerves in the same way as the teeth are for animals. Comparing teeth, odontods and sensory, they were all incredibly similar, she said.
“We believe that the earliest vertebrates, these large, armored fish, had very similar structures, at least morphologically. They look the same in ancient and modern arthropods because they all produce this mineralized layer that covers their soft fabric and helps them feel the environment.”
It is likely that the genes needed to form odontods also produced sensitive teeth for animals, including humans, later, according to the study, according to the study.
The results confirm the idea that the sensory structures first appeared in exoskets, which later provided genetic information, which could later be used to create teeth as they became a necessary part of life, the authors of the study noted.
“Over time, the fish has developed jaws and it has become useful to have pointed structures around and in the mouth,” Hardy said. “Little by little some fish with jaws on the edge of the mouth were pointed odontods, and finally some were straight into the mouth and then lost through the body. The connection of odontods and teeth is constantly explained by new fossils and modern genetics.”
The computer in the front of the skate is depicted with a solid skin -like skin of tooth skin (shown in orange). – Yara Harid/Chicago University
New studies clarify the first performance of hard fabrics and the earliest ancestors of the jaw fish by removing anatolepe of fish life, said dr. Head of Macroevolution at Lauren Sallan, Head of Macroevolution of the Institute of Science and Technology of Japan. Sallan, who did not participate in a new study, said it also raised an intriguing new hypothesis that the predecessors of shale teeth have evolved into the water to detect prey, friends or predators.
“This is a real challenge to seemingly obvious assumptions that heavy fabrics such as dental and structures such as scales and teeth have evolved (primarily) to protect the body or nourish the throat,” Sallan said. “Instead, they could have been ‘exiled’ (later modified) for these purposes, much like the limbs had developed before they were used on land. It is also interesting to see the degree of convergence of early armored vehicles and fish and raise questions about how many of these two groups have taken place. ”
Hariidi wants to continue the fossil that could cause the oldest vertebrate to search, given that the researchers expect to be previous vertebrates than “Astraspis” and “Eriptychius”. And while they did not find it in this study, they made the conclusions worthy of, “said Shubin Email. In the letter.
“We were disappointed that (Anatolepe) was not vertebrates, but we were surprised by the new ideas,” Shubin said. “And that led us in a whole new direction. It’s science.”
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