Conodonts appear
Tiny tooth-like fossils turn out, a century later, to belong to eel-like vertebrates.
- When
- Known to
- ± 5 million years
- Era
- Cambrian, Paleozoic
Conodont elements — phosphatic microfossils shaped like cones, blades and combs — appear in the Cambrian and become one of palaeontology's most valuable dating tools. For over a hundred years nobody knew what animal made them; the discovery of a fossil with the elements arranged in a head showed they were the feeding apparatus of a slender, eyed, jawless vertebrate. They remain the backbone of Paleozoic biostratigraphy.