I fully agree with your comments on the lack of direct illustration of evolutionary transitions in my book. If I knew of any, fossil or living, I would certainly have included them...I will lay it on the line – there is not one such fossil for which one might make a watertight argument.
Patterson's quote comes from a personal letter of 1979, written to Luther Sunderland (a creationist, although Patterson was unaware of this at the time). Sunderland had written to Patterson asking why his recently published book, Evolution, did not feature illustrations of transitional fossils from which modern species were descended. Adding the sentences before and after the second part of the quote clarifies Patterson's point:
You say that I should at least "show a photo of the fossil from which each type of organism was derived." I will lay it on the line – there is not one such fossil for which one could make a watertight argument. The reason is that statements about ancestry and descent are not applicable in the fossil record. Is Archaeopteryx the ancestor of all birds? Perhaps yes, perhaps no: there is no way of answering the question. It is easy enough to make up stories of how one form gave rise to another, and to find reasons why the stages should be favoured by natural selection. But such stories are not part of science, for there is no way of putting them to the test.
Patterson was explaining to Sunderland that, of the transitional fossils that were known, he could not make a watertight argument for any of them being the direct ancestor of a living species group. Archaeopteryx, for example, is not necessarily the direct ancestor of modern birds. It may have been a species on a side-branch.
Patterson's quote has been used extensively by creationists over the years, and creationists and anti-creationists have argued about its proper use. Consequently, creationists now tend to accompany their quotation of Patterson by suggesting his meaning was clear (they usually argue the clear meaning is that suggested by their edited quote, complete with the ellipses!) and any subsequent comment or clarification (including any by Patterson himself!) on the quote is a distortion of its true intent.
In The Greatest Hoax on Earth, Sarfati accompanies the Patterson quote with a footnote that says, "Patterson later tried to backtrack somewhat from this clear statement, apparently alarmed that creationists would utilize this truth." Patterson's own words are the best defence to such a claim. He made some strong statements in favour of evolution and against creationism in his second edition of Evolution, including comment on creationists' fondness for misquoting evolutionary biologists:
Because creationists lack scientific research or evidence to support such theories as a young earth (10,000 years old), a world-wide flood (Noah's), and separate ancestry for humans and apes, their common tactic is to attack evolution by hunting out debate or dissent among evolutionary biologists. When I published the first edition of this book I was hardly aware of creationism but, during the 1980s, like many other biologists I learned that one should think carefully about candour in argument (in publications, lectures, or correspondence) in case one was furnishing creationist campaigners with ammunition in the form of 'quotable quotes', often taken out of context.
I see the general historical theory, common descent, as being as firmly established as just about anything else in history. We have compelling reasons to believe that Napoleon and the Roman empire existed, although we don't know every detail of what went on in Napoleon's life or in Rome and its colonies; it is much the same with evolution. There is abundant documentary evidence for Napoleon and the Roman empire; there is abundant evidence for common descent in the hierarchy of homologies at both the structural and morphological level, though those documents may not be so easy to read.
Colin Patterson, Evolution (second edition) The Natural History Museum: London (1998), pages 122-3.
Lionel Theunissen, 'Patterson Misquoted: A Tale of Two 'Cites'' (1997) http://www.talkorigins.org/
Gary Bates, 'That quote!-about the missing transitional fossils' (2006) http://creation.com/that-
Richard Dickerson, 'Creationism and Evolution', Los Angeles Times (8 November 1989)http://articles.latimes.com/