Soft-bodied worms from the Burgess Shale fossil beds in Yoho
National Park, British Columbia, Canada have been known form
over 100 years. They are known by the name Spartobranchus tenuis
and are considered one of the most abundant species in the
Walcott Quarry community. However, only recently has a detailed
examination of their characteristics been made, leading to the
conclusion that they are ancient examples of acorn worms. One
member of the research team was Christopher Cameron from the
University of Montreal, who studies modern-day acorn worms.
Identifying the fossils was not problematic: "Spartobranchus is
clearly an acorn worm," he said in an interview. "It's almost
like someone took a picture of a modern-day animal - it's
absolutely astonishing." These animals are not true worms but
belong to a very different phylum: the Hemichordates. The name
means "half chordate" indicating that hemichordates share some
of the characters associated with chordates. This is relevant to
some of the discussion below. H