An Iguanodon with flippers

6 06 2007

There are some ideas in science that ultimately get forgotten, although they must have seemed pretty important at the time. Louis Agassiz’s idea of evolution being driven by cycles of catastrophic events and “new creations” is one such example, and I’m certain that his name recognition today is probably not what he hoped it would be. Still, while a good many hypotheses have been relegated to the trash bin of history, I think it’s important to look back and take note of scientific ideas that never quite made it, and Gerhard Heilmann’s 1927 opus The Origin of Birds contains such a wonderful illustration that I couldn’t resist sharing it.

I could write about what’s wrong with Heilmann’s hypothesis that birds evolved from archosaurs like Ornithosuchus and Euparkeria, but for now I will pass over this topic, especially since at the time he wrote the book he was not privy to the fantastic fossils coming out of China which have further solidified the relationship with dinosaurs and birds (Heilmann does note the closeness of small theropods and birds, although in the end he decides on the “pseudosuchians” as the best contenders). No, instead I want to bring into focus something Heilmann did right; refuting the notion that birds evolved from ornithiscian (“bird-hipped”) dinosaurs like Iguanodon and Camptosaurus. Besides the obvious issues with the time scale (the ornithiscian dinosaurs in question are younger than their proposed descendant, Archaeopteryx [or, Heilmann notes, Archaeornis, which was later found to be the same as Archaeopteryx]), the Iguanodon-bird link seemed entirely based upon the structure of the hip, other scientists so enamored with the bones that they disregarded everything else, producing some terrible “just-so” stories. Heilmann writes (p. 143);

Before proceeding, we take out one of the books accompanying us on our expedition. The title is “Extinct Animals” (London 1909), and, on opening it we happen to catch sight of a rather astonishing passage, p. 202: “In fact it is now certain that reptiles similar to the Iguanadon were the stock from which birds have been derived, the front limb having become probably first a swimming flipper or paddle, and then later an organ for beating the air and raising the creature out of the water for a brief flight. From such a beginning came the feather-bearing wing of modern birds.”

Dear me! How evident! we exclaim. The origin and evolution of the entire class of birds presented in a nutshell, and not the slightest doubt as to the correctness of the conclusion: “In fact it is now certain.” Hands off! All further investigations superfluous; we may just as well pack up again.

But are we really justified in relying upon our authority? we muse, turning to the title page, bearing the author’s name. We are struck with awe as we read: “E. Ray Lankester, M.A., LL. D., K.C.B., F.R.S., Late Director of the Natural History Department of the British Museum; Correspondent of the Institute of France.” And in the preface we further read: “This volume is a corrected shorthand report of the course of lectures adapted to a juvenile audience given by me at the Royal Institution, London.”

Well, then there can be no doubt whatever. No scientist, of course, would tell anybody, especially young people, what was not absolutely reliable. A pity, though, that he has not furnished us with an illustration, too, of this interesting process of evolution; it would have been a grateful task to draw the reptile “similar to the Iguanodon,” standing half-way in water, waving its paddle-like organs in the air, “raising the creature out of the water for a brief flight.”

Heilmann goes on to further desconstruct Mr. Lankester, but I couldn’t help but laugh out loud when I imagined a flippered Iguanodon and read Heilmann’s sarcastic response. Indeed, while the book may be old and full of technical language involving the names of bones (which Heilmann graciously depicts and labels throughout; it is a beautiful work) it surpasses many of the “popular” science books I have read recently, where authors are stingy with illustrations (did I mention Heilmann largely supplied his own for the book, in addition to writing it?) and are so concerned with using general terminology and metaphor that they trip over themselves. This is not true of all old books, of course, (Gosse’s Omphalos nearly killed me) but right or wrong Heilmann’s work has instantly become one of my most favorite works, and if you can find it I reccomend you get ahold of it.

In any case, there are far more stories to tell and old ideas to be inspected than anyone fully has time for, but I do think the history of science should be just as important to current students of nature as the newest Science or Nature paper. Some old ideas actually come back to life or appear to have elements of truth to them, and even if they do not (like a penguin/Iguanodon) they can serve to keep us humble; future researchers may end up laughing at our lofty ideas as well.


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8 responses

31 08 2007
Lars Dietz

This reminds me of W. Kitchin Parker’s idea (don’t know where it was published, but it was in the 19th century, I read about it in a paper by Fürbringer) that birds descended from “protovertebrates” (not yet reptiles) with the hind feet of a inosaur, the neck of a plesiosaur and the head of an ichthyosaur! He also claimed that the bird’s wing actually evolved from an ichthyopterygium (fish’s fin) insted of a cheiropterygium (tetrapod limb). Now I can’t stop imagining what that kind of creature would look like!

31 08 2007
laelaps

Sounds like a wonderfully weird creature, Lars. I’ll definitely have to keep my eyes open for mentions of Parker’s idea as I go through the various old books I have stacked up near the side of my couch. The further back I go and the sparser the fossil record is, the stranger the hypotheses seem to become!

31 08 2007
johannes

I owned a dinosaur book written by L.B. Halstead as a child. I had the German edidition, I don’t know the english name – “World of Dinosaurs” perhaps?
It was written in the mid seventies, was splendidly illustrated and contained many theories that were new and sensational back than – some have withstood the test of time (Ostroms thoughts about Deinonychus), some not (Chatterjees idea that ornithosuchians were early carnosaurs). Among the strangest reconstructions was “Compsognathus corallestris”, wich was depicted as an otherwise fairly normal, if rather long-necked small theropod, but with flippers instead of hands on its arms. The text said the flippers were used for locomotion. Whoever made this reconstruction had either never seen how waterfowls swim or had forgotten all about it. This looked a lot like Lars’ creature.

31 08 2007
Lars Dietz

Actually, i don’t know how accurate my comment was… it’s just my distant memory of Fürbrbringer’s presentation of an idea presented by Parker, who (according to Sibley & Ahlquist) wrote in a notoriously turgid and difficult style.
By the way, I won’t be able to comment on this for the next two days (no Internet access), so don’t woory, I’ve not forgotten this, I’ll look for the original citation.

4 09 2007
Lars Dietz

I’ve found a paper by Parker in the Proceedings of the Royal Society of 1887 here. It does’nt mention all off that stuff, but it frequently compares embryonic bird limbs with those of ichthyosaurs. It’s indeed quite difficult to understand wht Parker was actually saying about the origin of birds, but he writes a lot about metamorphosis. The paper is online at:
http://gallica.bnf.fr/ark:/12148/bpt6k56135c.item

4 09 2007
laelaps

Thanks Lars! I actually believe that I downloaded that one, although I haven’t had a chance to look at it yet. I also came across an old paper looking at convergences in mosasaur and Cretaceous toothed-bird jaws, which definitely looked very interesting. I really appreciate the work you put into digging this up.

4 09 2007
Lars Dietz

Thanks! As for the mosasaurs, it’s interesting to note that for some time (mid 20th century, I think) it was thought that the jaws of Ichthyornis actually belonged to a tiny mosasaur called Colonosaurus. Back to the subject of the post, I haven’t read Heilmann’s book yet, but there is no doubt that he was a great illustrator. Did you know that he also designed the Danish bank notes?

13 07 2008
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