One peculiar animal aptly named Hallucigenia (Fig. 55), to honor its
peculiar characteristics, was a wormlike creature that propelled itself across the
seafloor on what appear to be seven pairs of pointed stilts. However, a more
recent interpretation holds that two rows of spines across its back were used
for protection. A curious Burgess Shale animal called Wiwaxia was another
spiny creature about one inch long, possibly related to the modern scaleworm
known as a sea mouse. It resembled an undersea porcupine, with large scales
and two rows of spikes running along its back apparently for thwarting preda-
tors. It fed by scraping off fragments of food from the ocean floor with a rasp-
ing organ similar to a horny-toothed tongue.Figure 54Pikaiawas
the first known member of
the chordate phylum.
Figure 55The Burgess
Shale fauna Hallucigenia
is one of the strangest
animals preserved in the
fossil record.
Historical Geology