Pikaia gracilens is
an important member of the Burgess Shale fauna. Pakaia possesses
a stiff rod along its dorsal margin. The notochord like structure
paired muscle blocks suggests that
Pikaia may be a chordate. The narrow anterior end is
equipped with a pair of tentacles. The posterior end expands
into a fin-like tail. This lancelet like organism probably swam
an eel. Specimens average 5 cm in length (Selden & Nudds, 2004,
Burgess Shale gives paleontologists insight into the soft
body parts of the Trilobite Olenoides. The cephalon
(head) was equipped with three pairs of limbs and flexible antennae.
throacic segment (mid-body sections) had pairs of biramous limbs.
Unlike other trilobites Olenoides possessed antennae-like
appendages at it rear end called caudal furca. The walking
legs of Olenoides were equipped with
sharp inward facing spines. These spines may have been used
to shred food as it was passed forwards to the
mouth. Olenoides was a predator that probably fed on
a variety of worm-like organisms (Fortey, 2000, pp. 126-127).
R. (2000). Trilobite: Eyewitness to Evolution.
New York: Vintage Books.
P. & Nudds, J. (2004). Evolution of Fossil
Ecosystems. Chicago: The University of Chicago