Backbone

An early vertebrate

Haikouichthys comes from the Chengjiang fossil beds of southern China. It was only a few centimetres long and had no jaws. It stands in for the early-vertebrate body plan our ancestors passed through, not a proven direct ancestor.

What the evidence shows

• Many specimens preserve a head with eyes, possible nasal sacs and what may be ear capsules.
• A notochord with separate vertebral elements is identifiable: an early version of a backbone.
• Analysis places it among the earliest craniates, the group with a distinct head that includes all vertebrates.

What is reconstructed

• Its feeding, escape and social behaviour are not preserved in the fossils.
• Colours and the exact look of its fins are reconstructions.

Sources

• Shu et al. 2003. Head and backbone of the Early Cambrian vertebrate Haikouichthys. Nature. (opens the publisher’s site)

  What it supports: Haikouichthys anatomy: eyes, possible nasal sacs, and a notochord with separate vertebral elements. Behaviour and ecology are not preserved.

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