The first vertebrates
A small jawless fish — with a notochord
See it on the timeline →In depth
Myllokunmingia and Haikouichthys from the Chengjiang biota are among the oldest known craniates, with gill arches, a notochord and what are read as primitive eyes. They are small and unremarkable: the group that would give rise to every fish, amphibian, reptile, bird and mammal played no leading role in its own time. That is a recurring pattern in evolution — the lineages that later dominate almost always start out marginal.
For children
In China lie fossils of small, finger-length animals that swam in the Cambrian sea. They had a stiff rod along the back and muscles on either side, so they could swim by undulating. That rod later became the backbone — yours included.
Connects to
Part of Terra Saga — the story of Earth on a timeline. terrasaga.org