Amphioxus

(Or, what we like to call Sir Lancelet)

photo of an amphioxusWe humans have come a long way from our earliest chordates. Amphioxus, or the lancelet, is an animal that comes closer than any other to the transition group between invertebrates and vertebrates. Because they are early chordates and have all the chordate characteristics,. Amphioxus has been essential in understanding vertebrate evolution. Our human evolution.

graphic drawing of an amphioxus

These small, eel-like animals are very common in shallow sandy environments where they spend much of their time buried in sand. In some places there can be up to five thousand lancelets  per square meter of sand!
 

photo of a Pikaia fossil
The fossil record in the Cambrian Burges Shale yielded fossil ancestors: Pikaia from about 505 million years ago. And a fossil from the earliest Cambrian in China, Yunnanozoon, confirms that chordates appeared very early in the evolution of animals.

Watch the Shape of Life video Chordates