A new species of eel found in an undersea cave off Palau is a living fossil astonishingly similar to the first eels that swam some 200 million years ago.
The find is reported in the British journal Proceedings of the Royal Society, and was made last year in a 35-metre-deep fringing-reef cave off an island of Palau.
The small brown fish has very few of the anatomical characteristics of modern eels, a vast range whose 819 species are grouped into 19 families.
In contrast, it has many hallmarks of primitive eels which lived in the early Mesozoic era, back when dinosaurs ruled the Earth.
The similarities include a disproportionately large head, a short compressed body, collar-like openings on the gills, rays on the caudal fin and a jawbone tip called a premaxilla.
The discovery was made in March last year by a team led by Masaki Miya of the Natural History Museum and Institute in Chiba, Japan.