Ancient Armored Fish: How Their Bumps Could Be the Key to Understanding Animal Teeth Evolution

The story of teeth dates back to an unexpected source: fish swimming in Earth’s oceans around 465 million years ago. Our teeth, though hard on the outside, have a sensitive inner layer called dentine. This layer helps us feel pressure, pain, or changes in temperature from sweet to cold.

For years, scientists theorized about where teeth come from. Some thought they evolved from bumps on ancient fish, called odontodes, but their purpose remained unclear. Recent studies, including 3D scans of fossils, reveal that these bumps contained dentine, allowing fish to sense their environment. “When they bumped into something, they could sense the pressure,” says Dr. Yara Haridy from the University of Chicago.

Interestingly, these odontodes share similarities with sensory organs found in modern animals. Sensing structures in arthropods like crabs display similar traits, even though arthropods and fish evolved separately. This phenomenon is known as evolutionary convergence.

Dr. Haridy discovered that the ancient fish and extinct arthropods have a distant common ancestor that lacked hard parts. While arthropods still have sensory organs, odontodes paved the way for the first teeth in vertebrates.

During this research, the team also reassessed a creature named Anatolepis, initially thought to be an ancient fish but actually resembling an arthropod. This new understanding stems from advanced imaging techniques that provided high-resolution views of these fossils.

In an exciting twist, the study opens new doors to understanding how sensory structures, initially found on the bodies of ancient animals, contributed to the development of teeth as animals evolved.

Experts like Dr. Richard Dearden from the Naturalis Biodiversity Center commend this work for clarifying the classification of Anatolepis. The study indicates that armored fish like Astraspis and Eriptychius shared their habitat with giant squids and sea scorpions, and their sensory adaptations were crucial for survival.

The research also illuminates how features like odontodes may have helped ancient creatures detect predators or prey in a challenging environment. Over time, the evolution of jaws made it advantageous for but fish to develop pointed teeth for catching food.

As our understanding grows, researchers like Dr. Lauren Sallan highlight that the journey from sensory structures to teeth might have been more about survival than simply feeding. Discoveries like this remind us how science continually reshapes our understanding of life’s history.

As we analyze tooth-like structures in modern fish, researchers believe they still carry the echoes of their ancient ancestors. This ongoing exploration of our past promises even more revelations about how we came to be.



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