The soft tissue fossil record to elucidate the origin and diversification of vertebrates

The origin and diversification of vertebrates is a major event in the history of life on earth. A rich and well studied fossil record of jawed and jawless fishes exists following the advent of biomineralized hard tissues such as bone, but prior to this we are limited the soft tissue record. Soft bodied fossil vertebrates have the potential to help us understand the timing of key vertebrate innovations, including biomineralization itself. Indeed some taxa have been interpreted as exhibiting a kind of transitional state between the two conditions. The fossil record of soft bodied taxa is challenging however; the remains are subjected to decay, collapse, and distortion before and during preservation. These challenges have led to some disputes and a lack of consensus exists over the anatomy and affinity of these important fossils. New fossil discoveries, along with recent advances in scanning technology and a wealth of experimental decay data, means that it is now possible to she new light these previously enigmatic taxa and the nature of this important evolutionary event.