Uncovering the Secrets of 500-Million-Year-Old Fish Armor: Could This Be Why Your Teeth Hurt?

We all know that dental visits can be a bit uncomfortable. But did you know that tooth sensitivity has an important purpose? It helps us feel pressure and temperature while we eat. Interestingly, this sensitivity comes from a tissue called dentine, which might not have started in our mouths at all.

Recent research from the University of Chicago reveals that dentine evolved in ancient fish about 465 million years ago. Back then, it wasn’t about chewing but sensing the environment. These early fish relied on dentine-covered armor to detect movement and changes in water, which were crucial for survival.

Neil Shubin, one of the study’s authors, explained, “An early animal with armor needed to sense the world around it. This was a dangerous time, so the ability to feel changes in the water was vital.” Interestingly, it turns out that both vertebrates, like fish, and invertebrates, like crabs and shrimp, developed similar sensory solutions independently.

In the quest to uncover the oldest vertebrates, researchers examined fossils from the Cambrian period (485 to 540 million years ago). They found that many fossils previously thought to represent early vertebrates actually share characteristics with modern arthropods. Yara Haridy, a key researcher in the study, noted, “We thought we found the oldest vertebrate, but it turned out to be an arthropod instead.”

Despite this setback, another fossil named Anatolepis showcased some exciting findings. The scans revealed structures similar to dentine in its armor. Initially, this led the team to believe it could be a vertebrate. However, further comparisons showed that its armor was closer to the sensory organs found in modern crustaceans. This highlighted how “teeth” can serve sensory functions even outside the mouth, reinforcing the idea of sensitive armor across species.

On the evolutionary front, the study offers a fresh insight: teeth likely evolved from defensive armor. Modern sharks and catfish have skin structures called denticles that perform similar functions. Researchers speculate that early vertebrates used similar structures to sense their surroundings, suggesting an evolutionary link between armor and teeth.

The findings align with the theory that teeth originated as external structures before adapting for use inside the mouth. This challenges previous assumptions, showing a more complex evolutionary journey for teeth.

In summary, this research may not have found the earliest vertebrate, but it sheds light on how living creatures adapted and evolved over millions of years. This deeper understanding could change how we view not only our teeth but our evolutionary history as a whole.

The full study is available in the journal Nature.

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