Archaeopriapulid

Ottoia sp.

• Cambrian
• Burgess Shale, Stephen Formation
• British Columbia, Canada

Size: 5 cm

Here is a fossil from the famed Burgess Shale Lagerstätte, and one that showcases the exceptional soft-tissue preservation of the site. Ottoia is a genus of primitive softbodied archaeopriapulid worm, closely related to but distinct from true priapulids (a.k.a. "penis worms"). It is one of the most ancient predators in the fossil record and possessed an extendable proboscis lined with numerous small teeth and hooks for ensnaring prey, which appear to be visible on this specimen as the "fuzziness" of the anterior tip. Fragments of hyoliths have been found in the gut of some specimens, further indicating their carnivorous diet. Speaking of which, this specimen also preserves a clear blackened gut trace through its midline. It is flexed into a U-shape, which was thought to be the living posture of these worms as they burrowed into the seafloor.

While Ottoia prolifica is the most common species of this genus in the Burgess Shale and the most likely identification for this specimen, there is at least one other species O. tricuspida distinguished by its three-pronged teeth. Since I don't have the equipment nor the expertise to distinguish such fine structures, for now I will leave the identification of this specimen as Ottoia sp.