The researchers confirmed that early vertebrate fish had dentine-lined structures in their external armor.
First vertebrate teeth Some fossil teeth from even earlier – dating to the Cambrian period, between 485 and 540 million years ago – were also examined.
It now appears that both invertebrates and vertebrates developed sensory armor independently.
If confirmed, this would have pushed the record for the earliest vertebrate back by tens of millions of years.
While they didn’t find the earliest vertebrate fish, the researchers still uncovered something important.
Our teeth can be extremely sensitive; anyone who has ever flinched during a dental cleaning knows this. As we chew, the pain actually serves a purpose by assisting us in detecting temperature, pressure, and other sensations. However, this sensitivity did not originate in our mouths.
As it turns out, the dentine, or inner layer of teeth, originally evolved for a completely different reason: to aid ancient fish in sensing their surroundings.
At first, teeth served as armor.
The armored skeletons of ancient fish are where dentine first appeared, according to researchers from the University of Chicago. They examined fossils from the Ordovician period, some 465 million years ago.
This was not a chewing tissue in those days. Rather, it aided fish in detecting movement and water changes, which is a crucial survival ability in an environment full of predators.
The scientists verified that the external armor of early vertebrate fish featured dentine-lined structures. These were sensory aids rather than teeth. They assisted the fish in responding to their environment, much like skin or antennae do for contemporary animals.
teeth of the first vertebrates.
Additionally, some fossil teeth from even earlier times, from the Cambrian period (485–540 million years ago), were analyzed. They were believed to be the first vertebrate teeth.
The researchers noticed remarkable resemblances between them and the shells and armor of invertebrates, such as shrimp and crabs. It now seems that the development of sensory armor was independent for both vertebrates and invertebrates.
This early animal must be able to sense its surroundings when it swims around wearing armor. Being able to perceive the characteristics of the water surrounding them would have been crucial in this highly predatory environment, according to Neil Shubin, senior author of the new study.
Thus, we observe that armored invertebrates, such as horseshoe crabs, also require sensory perception, and coincidentally, they discover the same answer. “.”.
looking for the first vertebrate.
The goal of the project was to discover the oldest vertebrate known to science, according to Yara Haridy, a postdoctoral researcher at the University of Chicago.
She requested fossils from the Cambrian period from museums around the nation so that they could be examined for vertebrate characteristics. She searched for characteristics such as dentine inside odontodes, which are tiny bumps in the armor.
Even a toothpick could fit on many of the tiny samples. She brought them to the Argonne National Laboratory for a more thorough analysis.
There, the group used a powerful synchrotron at the Advanced Photon Source to scan the fossils for the entire night.
“It was enjoyable to spend a night at the particle accelerator,” Haridy remarked.
Anatolepis, one of the fossils, showed promise. Under its armor, tubules filled with dentine-like material were visible through the scans.
It appeared to be a vertebrate at first glance. This would have pushed back the record for the earliest vertebrate by tens of millions of years if it were verified.
“We were giving each other high fives, like, ‘Oh my God, we did it at last,'” Haridy remarked. That would have been the earliest tooth-like structure found in Cambrian vertebrate tissues. Therefore, when we noticed the telltale signs of what appeared to be dentine, we were quite excited. “”.
After all, Anatolepis was not a vertebrate.
Undoubtedly, the group began contrasting Anatolepis with other extinct and contemporary creatures. Sharks, skates, barnacles, snails, and even catfish that Haridy had bred in her own aquarium were among them.
One unexpected finding resulted from the comparisons. The sensilla, which are microscopic sensory organs that enable crabs and shrimp to sense their surroundings, were nearly identical to the structures in Anatolepis. Anatolepis was actually not a vertebrate, as it turns out. Most likely, it was an arthropod.
This demonstrates that even when “teeth” are not in the mouth, they can still have sensory properties. Therefore, these fish have sensitive armor. These arthropods have sensitive armor, Haridy exclaimed.
This clarifies the misunderstanding regarding these early Cambrian creatures. This was an arthropod, not the earliest vertebrate as people believed. “.”.
The presence of dentine in comparable structures in another fossil, this one belonging to the vertebrate Eriptychius, demonstrated that sensory armor was also found in actual vertebrates.
The origins of teeth, armor, and defense.
The research also provides a new understanding of how teeth developed, presumably from a form of protective gear that the earliest vertebrates employed. These days, sharks, skates, and catfish have skin structures called denticles that resemble teeth.
Upon examining her catfish, Haridy discovered that, like actual teeth, these denticles were attached to nerves.
We believe that these large, armored fish, which are the earliest vertebrates, shared many morphological characteristics. Because they are all producing this mineralized layer that covers their soft tissue and aids in their sense of surroundings, ancient and modern arthropods appear to be identical, she explained.
Regarding the origin of teeth, there are two primary theories. It is said that teeth first appeared on body armor after evolving inside the mouth.
According to the other theory, they began as external sensory structures before subsequently evolving into teeth. In this study, the second idea is supported.
The scientists discovered something significant even though they were unable to locate the earliest vertebrate fish.
We demonstrated that several of these fossils, which were thought to be early vertebrates, are not. However, that was somewhat misleading, Shubin stated. We didn’t discover the oldest one, but we did discover something much more amazing in some respects. “.”.
The journal Nature published the entire study.
——.
Check us out on EarthSnap, a free app developed by Earth . com and Eric Ralls.
——.
