Hallucigenia sparsa is the name of a "velvet worm" or
onychophoran known only from
fossils in the
Cambrian Burgess
Shale formation, found in the Canadian
Rocky Mountains.
Hallucigenia
have long spiny legs projecting at right angles from a wormlike body,
with claws at the end. They also have long spiny projections coming
out of their backs, also at 90-degree angles to each other. This
makes it look like a row of "X"'s connected by a central tube, making it
look something...like...some...obscure piece of electronic equipment.
The following diagram may help, but again, it may not:
\ \/ \/ \/ \/ \/
\/ \/ /
__\_/\_/\_/\_/\_/\_/\_/\_/__
(____________________________)
/ \/ \/ \/ \/ \/
\/
\/ \ m
/ /\ /\ /\ /\ /\
/\ /\ \
The organism was named during studies of the Burgess Shale in the early
1980's. At that time, the only Hallucigenia fossils
known showed only the spiny protrusions on their back. The first reconstruction
of a Hallucigenia from these fossils was upside down, resulting
in an even more bizarre appearance for the creature than was the case.
Hallucigenia have some small tentacles on the ventral side at
one end (the m), but their function is unknown. To
this day, scientists still cannot tell which end of a Hallucigenia
is which, and only know which side is down from the claws at the ends of
the creature's feet.