#priapulida

Louisella

Reconstruction by Marianne Collins

When: Cambrian (~505 million years ago)

Where: British Columbia, Canada 

What:  Louisella is a worm-type organism from the Burgess Shale formation in the Canadian Rockies of BC. This organism was about 12 inches (~30 centimeters) long, with a proboscis at its anterior end that could be inverted into the body or extruded. In the images above it is inverted into the body in the fossil specimen, but shown at its full  extended length in the reconstruction. This structure was ringed by a series of spines with shorter and more robust spikes on the end of the proboscis. These structures would rub past one another as the animal extended and retracted its proboscis, allowing it to ‘chew’ its food. The rows of short fringes on one surface of Louisella are thought to possible have been the animal’s gills. This worm has been reconstructed as a burrowing and carnivorous creature, and due to the grinding capability afforded to it by its proboscis, it likely ate animals of a relatively large size. 

Louisella is currently held as a stem fossil on the lineage leading to the Priapulida worms, also known as the 'Penis worms’. I swear I am not making that up. These worms are very rare even today, with less than 20 living species known. They, like their ancient relative, are burrowing creatures which hunt other invertebrates. Fossils of priapulid worms are also rare, only a handful of Louisella specimens are known. What is far more common though are their distinctive shaped burrows, which are sort of an interlocking L-shape. The appearance of this type of burrows is one of the biostratigraphic markers of the start of the Cambrian period. 

Louisella on the ROM’s amazing Burgess Shale website