Now, a new fossilized fish skeleton found in China is older than the next-oldest specimen by a whopping 15 million years and is the, “oldest undisputed jawed fish.” ...

In experiments applying mechanical stress on microscopic samples of shark vertebrae, the researchers observed tiny deformations—less than a micrometer—after a single cycle of applied pressure.

Unlike many shark skeletons, these individuals were preserved in 3D. Emma Bernard, who looks after the fossil fish collections, explains that this is due to how they were preserved.

Blacktip shark, cartilage of a blacktip shark Journal Reference: Dawn Raja Somu, Steven A. Soini, Ani Briggs, Kritika Singh, Imke Greving, Marianne Porter, Michelle Passerotti, Vivian Merk.