Again, a fine piece of X-ray detail, and equally fine stiple gradation upon the subject itself. I'm also impressed by that angular skull & set of fish-hook teeth...as well as the equally brutal-looking background fish. Xiphactinus, I presume?
Always a pleasure to peruse your paleo-works (pardon the alliteration).
The purpose of this picture was to show how a paddle evolved from a manus through the process of polyphallangy (multiplication of knuckles). The companion work on Ichthyosaurs was to show polydactyly (the multiplication of fingers).
The intention of the article was to introduce fantasy artists to very BASIC notions of functional morphology so that the fantastic creatures they rendered (unicorns, dragons, chthullus, whatever) might have some credible anatomy.
I said what I wanted to say, but I doubt if more than a few hundred artists ever saw this article that was published in 1980. I have considered other more ambitious projects in the intervening decades but others beat me to it. I was working on a book on "future dinosaurs" when Dougal Dixon did his own series of books and essentially flooded the market.
I wouldn't call it a "series of books" - each of these books was a separate work, not really related to each other: "After Man: A Zoology of the Future", "Man After Man" and "The New Dinosaurs" do not have much in common with each other at all.
Dixon's concepts are 20 years too old - of course "Primeval" and its producer, Impossible Pictures, are stripmining the concepts. If you want to see the more recent versions of Dixon's concepts, you should find the series "The Future Is Wild" (the original series, not the cartoon one) and see it. You won't forget them in a hurry, that's for sure!