Ah... Gish and his missing fish!
Is he still standing by his claim that "fossilized fish abruptly appear fully formed in Cambrian rocks, and no one has found a single transitional form between invertebrates and fishes"?
"Proterozoic Metazoan Body Fossils." Bruce N. Runnegar and Mikhail A. Fedonkin,
The Proterozoic Biosphere 369-388
"New Silurian and Devonian fork-tailed 'thelodonts' are jawless vertebrates with stomachs and deep bodies." Wilson and Caldwell,
Nature 361:442-444
'Science and Earth History - The Evolution/Creation Controversy' by Arthur N. Strahler contains a section on possible precursors to Cambrian metazoans .
References obtained in an article by Richard Trott, talkorigins archives.