@ 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.