Sharpest teeth

The sharpest teeth of any animal belong to the conodont (Conodonta) class of eel-like vertebrates that evolved ca. 500 million years ago in the Precambrian eon. Despite being jawless, conodonts had teeth with tips as small as 2 micrometres across (1/20th the width of a human hair). X-ray analysis of fossils of the conodont species Wurmiella excavata reveal delicate but razor-sharp food processing structures that sliced left to right (as opposed to the typical up and down bite). Conodonts are also understood to be the first creatures to evolve teeth. Conodonts can grow up to 40 cm in length. They are believed to have been made extinct during the Triassic Period (ca. 200 million years ago).

The research was revealed in Proceedings of The Royal Society and co-authored by David Jones, Alistair R. Evans, Karen K. W. Siu, Emily J. Rayfield, and Philip C. J. Donoghue.

The original abstract reads: "Conodonts have been considered the earliest skeletonizing vertebrates and their mineralized feeding apparatus interpreted as having performed a tooth function. However, the absence of jaws in conodonts and the small size of their oropharyngeal musculature limits the force available for fracturing food items, presenting a challenge to this interpretation. We address this issue quantitatively using engineering approaches previously applied to mammalian dentitions. We show that the morphology of conodont food-processing elements was adapted to overcome size limitations through developing dental tools of unparalleled sharpness that maximize applied pressure. Combined with observations of wear, we also show how this morphology was employed, demonstrating how Wurmiella excavata used rotational kinematics similar to other conodonts, suggesting that this occlusal style is typical for the clade. Our work places conodont elements within a broader dental framework, providing a phylogenetically independent system for examining convergence and scaling in dental tools."