Evolution

Press, 23 October 1989, Page 16

Evolution

Sir,—D. H. Karst (October 18) succeeds only in reflecting the intellectual aridity of Denton’s book. Denton selectively quotes from a paper by Forey on the living coelacanth so as to support his (Denton’s) contention that serious considerations cloud the status of the Rhipidistia (an early bony fish group) as possible amphibian ancestors. The implication is that the “gap” between fish and tetrapods reriiains vacant. What he conveniently overlooks is that in spite of the coelacanth’s soft anatomy not conforming to what might be expected of a tetrapod relative, Forey after due consideration is still able to suggest that “amongst recent fishes, it is the cousin of tetrapeds.” This tallies with the current view that the coelacanths were off the “main line” of evolution towards land vertebrate?. For your correspondent’s further edification. Ichthyostega had no gili area, which is why it had no need of an operculum. Thus its possession of preopercular bones is highly suggestive of a fish ancestry.— Yours, etc., WARWICK DON, Senior Lecturer in Zoolj® ogy, University of Otago. October 19, 1989.