Page 112 - The Cambrian Evidence that Darwin Failed to Comprehend

The Cambrian Evidence That Darwin Failed to Comprehend

A fossil Anomalocaris
A reconstruction of fossil Anomalocaris

Pikaia
Pikaia was first described by Walcott as a marine worm.
However, because of several of its features, it was included in the
phylum Chordata, which also includes vertebrates. The first known
Cambrian representative of this phylum, it had a pair of short tenta-
cles on the front. The trunk consisted of solid blocks of muscle,
curved in an S shape. The tail expanded in the form of a fin. Pikaia
swam just above the sea bed. It propelled itself by using the muscles
to undulate its body. 77

Opabinia
Opabinia is a creature found in the earliest Cambrian rock beds
and possesses characteristics very different from other life forms. It
had a segmented trunk and a soft shell. There were five eyes on its
head. More interestingly, it had a proboscis on its head, which end-
78
ed in spines. This was probably used for grasping preys. Each of
the trunk segments had a pair of gills. The hindmost three segments
comprised the tail.
Thanks to Opabinia, scientists realized that the soft-bodied

110