Fossil History

It is thought that holothuroids most likely evolved from a group of extinct Palaeozoic echinoderms known as ophiocistioids. This occurred during the lower Silurian era. Conversely, the oldest body fossil recorded of a holothuroid was supposedly from the Devonian period, while the oldest ossicle is from the Upper Silurian (Boczarowski 2001). More research in this area is required to generate precise and accurate sea cucumber fossil data.  It is extremely difficult to generate fossil records for soft-bodied animals. Published body fossil records already exist for approximately a mere 19 species of sea cucumber and in some cases body fossil species have been found but are yet to be identified (Reich 2006). By examining isolated ossicles in sea cucumber fossils it is possible to identify ancient holothuroids. Microscopic ossicles involve a complex collection method and since there are few specialists working in this area, holothuroids fossils are quite rare.

Analysing elements of the calcareous ring is another method previously used to distinguish sea cucumber species (Gilliland 1993). Unfortunately not enough work has been done in this area to formulate any significant or reliable results.