Exceptional Priapulid Fossil from Cambrian Utah

Description: This unusual specimen shows a large priapulid worm. Priapulid worms are among the fossils also found in the Burgess shale and older Chengjiang Biota, and ancestors are still extant today. They are as biologically complex as arthropods, and are thus important in the Cambrian fossil record. Taxonomically, they belong to a group named the Cephalorhyncha that are ecdysozoan animals -- encompassing the arthropods (insects, spiders, and crustaceans) and the nematodes. The grouping is based on a set of shared characters including the presence of a cuticle and the fact that they periodically shed their cuticle in a process called ecdysis. All cephalorhynchs have an evertible spiny proboscis that is used to gather food. Notice the gut trace seen in this example.