@ Dr. Heinz Lycklama
Fully Formed
“It is considered likely that all the
animal phyla became distinct before or during the Cambrian,
for they all appear fully formed, without intermediates
connecting one phylum to another.”
Futuyma,
Douglas J. 1986. Evolutionary
biology.
2d
ed. Sunderland, MA: Sinauer Associates, Inc. p. 325.