Animals

Chordata

This group includes conodonts. These animals all have a notochord (a flexible backbone-like structure) and a nerve cord running down the dorsal side (back side) of the body. They also have gills at some point in their development. Tiny conodont teeth are very common fossils throughout the Paleozoic, and are often used to help determine the age of rocks.

 

For more information:

http://www.palaeos.com/Vertebrates/Units/030Conodonta/030.000.html