Research Highlight - Fossil Scans Reveal Teeth Evolved from Ancient Sensory Structures

A new study has rewritten the story of how teeth first evolved,showing they likely originated not just for biting but as part of an ancient sensory system. Using advanced synchrotron X-ray imaging,researchers analyzed controversial Cambrian fossils once thought to belong to early vertebrates. The findings reveal these fossils,previously called Anatolepis, were actually arthropods—early relatives of crabs and insects—with sensory structures, not true teeth.

Fig 1: CT scan of the front of a skate,showing the hard,tooth-like denticles (orange) on its skin (by Yara Haridy from the University of Chicago).

The research team compared these fossils to confirmed early vertebrates,such as the jawless fish Eriptychius from the Ordovician period. The scans showed that while Eriptychius had true dentine-based odontodes, they lacked hard enamel caps, leaving their tubules exposed—a feature suggesting a sensory role. To test this,scientists examined modern fish, including catfish and sharks,and found dense nerve connections around their external tooth-like scales, supporting the idea that these structures detect touch and pressure.

Fig 2: Ultrastructural similarities between vertebrate odontodes and arthropod sensorial structures.

This discovery shifts the understanding of teeth’s origins. Rather than evolving purely for protection or feeding, the earliest odontodes may have functioned as part of a"sensory armor," helping early vertebrates navigate their environment. The study also highlights an evolutionary parallel: both vertebrates and arthropods independently developed mineralized sensory systems in their outer coverings.

With Anatolepis now reclassified,the oldest confirmed vertebrate teeth come from later Ordovician fossils. The research underscores how sensitivity in modern teeth traces back to their ancient role as sensory organs—a legacy still felt every time we bite into something hot or cold.

Reference

Haridy,Y.,Norris,S.C.P.,Fabbri,M. et al. The origin of vertebrate teeth and evolution of sensory exoskeletons. Nature (2025). https://doi.org/10.1038/s41586-025-08944-w