2007 - Ries, CJ - Inventing the four-legged fish (Ideas in History)

© Ideas in History Vol. II • No.1/07

Christopher J. Ries

Inventing ‘the four-legged fish’The palaeontology, politics and popularity of the Devonian

tetrapod Ichthyostega, 1931-1955.1

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Abstract

The first specimens of the Devonian tetrapod Ichthyostega were found on the Danish Three-Year Expedition to East Greenland 1931-1934 under the leadership of the

Danish geologist Lauge Koch.Being the earliest known four-legged animal at the time, the

creature was immediately dubbed ‘the four-legged fish’ and launched into public space as a missing link in the history of evolution from the time when vertebrate life first ventured onto dry land from the sea. Over the following decades, the popular scientific icon of ‘the four-legged fish’ served as a vessel not only for scientific interest, but also for international and institutional rivalry and the personal ambition of individual scientists.

This paper traces the fate and tracks of the Devonian tetra-pod Ichthyostega as it traversed, bridged and blurred the divide between ‘popular imagination’ and ‘scientific knowledge’ between 1931 and 1955. For it is a striking fact, that while

1 Valuable comments on various stages of this article has been offered by Hans Bjerring (Stockholm), Henning Blom (Uppsala University), Jennifer Clack (Cambridge University) and Gilles Cuny (Geological Museum, Copenhagen). While profoundly grateful for the help from these people, I remain solely and completely responsible for any errors or inaccuracies. The following abbrevia-tions for manuscript collections are used: (LK) Lauge Koch’s Personal Archive, The Danish National Archive, Copenhagen, Denmark (parcel number follows ‘/’); (SASO) Gunnar Säve-Söderberghs Papers, Museum of Evolution, Uppsala University, Uppsala, Sweden; (NN) Arne Noe-Nygaard’s Personal Archive, Geological Museum, Copenhagen University, Copenhagen, Denmark; (RMOG) The Archives of the Editorial Board of Meddelelser om Grønland, The Danish National Archive, Copenhagen, Denmark (parcel number follows ‘/’);

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Inventing ‘the four-legged fi sh’

during this period vertebrate palaeontologists deliberated on the form and status of Ichthyostega in the history of evolution, the image of a ‘four-legged fish’ settled in the public imagina-tion to such a degree, that it shaped scientific lore about the animal until the late 1990s.

1. Introduction

In September 2005 a new and long awaited reconstruction of the Devonian tetrapod Ichthyostega appeared in Nature.2 The reconstruction, proposed by palaeontologists Jennifer Clack, Per Ahlberg and Henning Blom, was juxtaposed with another published in 1996 by the Swedish palaeototlogist Erik Jarvik (1907-1998) 3 [Fig. 1]. For more than 40 years Jarvik had remained the international authority on Ichthyostega, main-taining with only very minor revisions his reconstruction first published in 1955 in the popular scientific journal American Scientific4 [Fig. 2].

Fig. 1. Top: the new reconstruction of Ichtyostega according to Clack, Ahlberg and Blom. Bottom: Jarviks reconstruction as depicted in Jarvik, 1996. Source: Clack, et al., “The axial skeleton…” Nature, 2005.

2 Jennifer A. Clack, Per Ahlberg and Henning Blom, “The axial skeleton of the Devonian tetrapod Ichthyostega”, Nature, 2005, 437:137-140.3 Erik Jarvik, “The Devonian tetrapod Ichthyostega”, Fossils and Strata, 1996, 40:1-213.4 E. Jarvik, “The earliest tetrapods and their fore-runners”, Scientific Monthly, 1955, 3:141-154

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Jarvik’s 1955 reconstruction was not his first attempt at visu-alising Ichthyostega. An earlier version was published three years before in the scientific journal Messages on Greenland5 [Fig. 3]. While this version did not boast a reconstruction of the whole body skeleton, the general outline is still quite similar to Jarvik’s 1955 version. Nevertheless, the difference in the position of the hind limbs is quite striking. In this aspect, the 1952 version, in fact, corresponds more closely with the version proposed in Nature in 2005.

Fig. 2 Jarvik’s 1955 version of Ichthyostega. Source: Jarvik, “The earliest tetra-pods…”, Scientific Monthly, 1955.

Jarvik wrote in 1952 that he had depicted the hind limb point-ing backwards as it appeared in the fossils.6 But why then did he twist it around in 1955? And how did Jarvik’s 1955 version, originally conceived for a popular audience, become and remain accepted as scientifically correct for more than 40 years? In the following, some light will be shed on these questions.

5 Erik Jarvik, “On the fish-like tail in the ichthyostegid stegocephalians with de-scriptions of a new stegocephalian and a new crossopterygian from the Upper Devonian of East Greenland”, Meddelelser om Grønland, 1952, 114(12): 1-90.6 Jarvik, “On the fish-like tail”, p. 21.

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2. Early vertebrates and international politics

The first fossils of Ichthyostega were found in 1931 by a group of palaeontologists on the Danish Three-Year Expedition to East Greenland 1931-34.7 In the decades between World War I and World War II, East Greenland was the scene of intense national rivalry between Denmark and Norway over the right to sovereignty and scientific investigation. With ever-growing intensity expeditions were dispatched with trappers, scientists and national flags to mark the determination of the rivalling nations in their engagement with the region. Geo-political tension reached a climax in the summer of 1931, when a team of Norwegian trappers raised the Norwegian flag over their hut and claimed part of the coastline for Norway. Shortly after, the Norwegian government acknowledged the claim, whereupon the Danish government lodged a complaint with the International Court in The Hague.

Fig. 3. Jarvik’s 1952 version of Ichtyostega. Source: Jarvik, “On the fish-like tail…”, Medd. om Grønland, 1952.

7 In fact specimens had been collected by the Swedish geologist Oscar Kulling already on Lauge Koch’s East Greenland expedition in 1929, but only later were they recognised as tetrapods. See Erik Stensiö, “Upper Devonian Vertebrates from East Greenland. Collected by the Danish Greenland Expeditions in 1929 and 1930. With 36 plates and 95 figures in the text”, Meddelelser om Grønland, 1931. 86/1: 1-213.

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It was in this climate of intense geo-political rivalry that Denmark launched the Three Year Expedition to East Greenland 1931-34 under the leadership of the Danish geologist Lauge Koch. At the time Koch, having conducted geological investigations in Northern and North-Eastern Greenland on numerous expeditions in the 1910s and 1920s, was counted among the top international experts on Greenland geology, enjoying the confidence and unfailing support of the Danish Prime Minister, Thorvald Stauning, as well as that of the Director of the Danish Greenland Administration, Jens Daugaard-Jensen. 8

The Three-Year Expedition was the largest expedition that had ever set out from Denmark. Every summer close to a hundred expedition members descended upon the East Greenland coast to amass scientific results to be publicly announced via radio, newspapers and internationally acclaimed scientific journals. And it was on this expedition that in August 1931 a team of geology students, all in their early twenties, went tracing the slopes of Mount Celsius, Ymer Island, for fossil remains of Devonian vertebrates. Leader of the team was Gunnar Säve-Söderbergh of Uppsala University who, under the guidance of Professor Erik Stensiö of the Swedish Natural History Museum in Stockholm, had been studying the material collected on previous Koch expeditions to the same locality.

Since Stensiö’s appointment as a professor at the museum in 1923, the Section of Paleozoology had grown to become an international centre for research in early vertebrates, and students from all over the world were drawn to Stockholm to work under Stensiö’s charismatic and undisputed leadership.9 In 1921, the publication of Stensiö’s doctoral thesis on Triassic sharks and bony fishes from Spitsbergen had caused a revolu-tion in early vertebrate palaeontology. Until the beginning of the 20th century, palaeozoic fishes had generally been described as they presented themselves in the rock, and classified on the basis of exo-skeletal anatomical features such as the scales or

8 For a fuller description of Lauge Koch’s career, see Christopher J. Ries, Retten, magten og æren. Lauge Koch Sagen, (Copenhagen, Lindhardt og Ringhof), 2003, and Christopher J. Ries, “Lauge Koch and the Mapping of North East Greenland: Traditon and Modernity in Danish Arctic Research”, pp. 199-231 in Michael Bravo and Sverker Sörlin eds., Narrating the Arctic. A Cultural History of Nordic Scientific Practices (Canton: Science History Publications, 2002).9, Early vertebrates, 1996, (Oxford: Oxford University Press), on p. 316.

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the pattern of the dermal bones on the head. Stensiö, on the other hand, made every effort to remove the rock around his fossils, dissecting through them to reveal internal anatomi-cal features.10 The success of Stensiös investigations largely stemmed from his use of the method of grinding away thin ‘slices’ of fossils to reveal minute and otherwise inaccessible internal anatomical structures in his specimens. Thus, it was Stensiö who pioneered the modern way of looking at these fossils as living animals.

It was therefore only natural that Koch, looking for experts to handle the Devonian vertebrate fossil material from his expeditions, turned to Stensiö for assistance. Stensiö, in return, was always looking for means to maintain and to expand his institute and scientific reputation, and was drawn to Koch for the vast amount of material and the economic support offered to him by the Danish state in the attempt to outshine the Norwegian exploratory campaigns in East Greenland.

It was in this intensely competitive politico-scientific climate that Säve-Söderbergh’s team in 1931 found seven fossil skulls and some other fragments of a previously unknown type of ‘stegocephalian’ from the late Devonian period about 360 million years ago. Stegocephalia was a blanket term including all pre-Jurassic amphibians: a large and heterogenous group of four-legged intermediate stages between fishes and reptiles, considered to predate the development of the major land-dwell-ing animal groups of dinosaurs, reptiles, mammals and birds. A trait common to these stegocephalians and their closest possi-ble relatives among the fishes – the so-called ‘crossopterygians’ [Fig. 4] - was a thick dermal skull of ossified connective tissue with openings for the eyes and nostrils. Comparing such skulls was one of the ways that palaeontologists tried to clarify the evolutionary relationships in the Devonian vertebrate fauna.

10 Colin Patterson, “Erik Helge Osvald Stensiö”, Biographical Memoirs of Fellows of the Royal Society, 1990, 35: 363-380, p. 366.

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Fig. 4. The Devonian crossopterygian Holoptychius, as depicted in Säve-Söderberg, 1938, p. 150. Specimens of this species achieved a length of one to two metres.

When studying the relationships between different groups of Devonian vertebrates it is useful to compare the system of lateral lines with which fishes sense movements, currents and pressure in the water. Since these lines penetrate and embed themselves in the dermal bones of the skull, it is possible to identify those dermal bones of different species, which contain similar parts of the line system. Among closely related forms the dermal bones and line patterns of the skull were similar in number and pattern, but before Säve-Söderbergh’s discovery, this method could not be used to compare fishes and early tetrapods.

Until then, the oldest known stegocephalians were of Carboniferous origin – about 310 million years old – and even if these did show grooves for lateral lines in their dermal skulls, it was difficult to assess the relationship between these grooves and the deeper-lying canals in the fishes. In other words, investigations of Carboniferous stegocephalians hinted at some form of kinship with the fishes, but they also revealed a considerable evolutionary gap between the two groups.11 The Devonian tetrapod found by Säve-Söderbergh in 1931 was, therefore, extremely important from a scientific point of view, and upon his return from Greenland that autumn Koch invited Stensiö to witness the unpacking of the sensational fossils.

But the new material was also of political importance to Denmark in view of the forthcoming trial at the International Court in The Hague in the summer of 1932, of which Stensiö was well aware. In March 1932 he wrote to Koch: “The stego-cephalian material is simply wonderful. As far as I can see,

11 Gunnar Säve-Söderbergh, “På jagt efter Østgrønlands fortidsdyr”, pp. 142-157 in Gunnar Thorson ed., Med Treaars Ekspeditionen til Chr. X’s Land, (Copenhagen: Gyldendal, 1937) pp. 148-49.

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Säve-Söderbergh will not be able to finish a full treatise in time, but he will certainly publish a good preliminary description, to make it clear that the merit and honour of this discovery, so very important to palaeontology, belongs to Denmark.”12 Koch, on the other hand, was more cautious, and worried that premature publication of the sensational material might cause more harm than good. “I am especially concerned,” he wrote to Stensiö, “that a number of Norwegian vessels will probably be laid up and rather inexpensively for hire this summer. If such a publication is out by July 1st, a smart American tourist could easily pursue the greatest dream of many tourists, which is to become the leader of ‘a real scientific Polar expedition’, and start poaching on our reserves.”13 While Koch agreed that a forthcoming treatise on the Devonian stegocephalians should be announced at the preliminary court hearings in the summer of 1932, an actual publication would have to wait. Hopefully, another summer alone in the field would give Säve-Söderbergh enough of a head start to discourage foreign competition and leave the Devonian tetrapods securely in the hands of Koch, Stensiö and their collaborators.

3. It’s alive!

And so it was that while, in July 1932, the Danish and Norwegian delegations were busy discussing in court, Säve-Söderbergh and a team of Swedish assistants revisited Mount Celsius looking for more Devonian vertebrates. When the expedition returned to Copenhagen on September 18th 1932, Säve-Söderbergh’s ‘preliminary investigation’ of the Devonian stegocephalians had not yet been published. But it was close to completion, so Koch decided to let the cat out of the bag, and in the weeks that followed, his success was celebrated in news-papers around the world. “Dr. Lauge Koch” wrote the New York Times, “veteran Arctic explorer, today returned from Greenland with the announcement that he had found evidence of one of the missing links in the chain of evolution – a four-legged fish that walked ashore (...) The stegocephali, he says,

12 Stensiö to Koch, 7/3-32, LK/13.13 Koch to Stensiö, 21/3-32, LK/13.

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were creatures with four legs. Halfway between fish and toads in the evolutionary scale [...] This remarkable quadruped could walk on land as well as live in the sea.”14 Considering the fact that only some skulls had been identified at this time, Koch’s statement was perhaps rather bold, but as an eye-catcher for the general public, it was very much to the point.

In Nordwestdeutsche Zeitung Stensiö announced that the four-legged fish matched the Jurassic lizard-bird Archaeopteryx in scientific importance15, while Koch called the discovery of the creature ‘the greatest achievement of his expedition’.16 And clearly, while he also reported on newly found deposits of lead, zinc and silver, it was the tetrapod that got all the attention. Koch was probably not far off the point in assuming that the price of the specimens, if sold to a museum, would cover the whole expenditure for the Three Year Expedition.17 On September 20th, Koch received a letter from New York University with a bid on any number of specimens that might be for sale.18

To most scientists, of course, a Devonian tetrapod meant yet another piece in the puzzle of evolution. But the scarcity of information available along with extensive media coverage allowed for a wide range of ‘non-professional’ interpretations of the animal. On September 22nd, Charles Schuchert of the Peabody Museum of Natural History in Connecticut, Ohio, reported to Koch of the public interest in his latest discovery:

My dear Lauge Koch. All hail to the most heralded man of science in Denmark and Greenland! We see your name on the front pages of our daily papers, and your portrait inside, hear your name over our radio, and find cartoons about you on the editorial page of our New York Tribune. […] Fish stories every man loves to hear [...] and Lauge Koch has the most wonderful

14 “Legged-fish fossils by thousands found on Greenland shore”, New York Times, 19/9-32. 15 For an interesting parallel to the present article regarding Archaeopteryx and the evolution of birds, see Christopher Jacob Ries, “Creating the Proavis: bird origins in the art and science of Gerhard Heilmann 1913-1926”, Archives of Natural History, 2007, 34, 1: 1-18.16 “Wichtige Ergebnisse der dänischen Ostgrönlandsexpedition”, Nordwestdeutsche Zeitung, 25/9-32.17 “Legged-fish fossils”, New York Times, 19/9-32.18 Free to Koch, 20/9-32, SASO, Correspondence K-N.

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of them all. Professor Gregory of the American Museum ap-parently does not believe you have a Devonian Stegocephalia, and last Sunday the editor of the New York Times discussed your find, but I swear by Lauge Koch and his fish with legs. Hoch soll er leben! Yours truly, Charles Schuchert.19

All things taken into account, ‘the four-legged fish’ was already widely known when the first scientific article in its honour – Säve-Söderbergh’s ‘Preliminary note on Devonian Stegocephalians from East Greenland’ – was published in mid-November (Säve-Söderbergh, 1932) [Fig. 5]. Letters of

interest and congratula-tion began to arrive in Uppsala, Stockholm and Copenhagen. In late December, Stensiö reported to Koch of the considerable enthusiasm and expectation with which the news had been received among palae-ontologists, zoologists and geologists all over Europe, from Hungary to Great Britain.20 The potential of the mate-rial was further increased when in East Greenland during the summer of 1933, Säve-Söderbergh found a fossilized skull of a hitherto unknown

type of Devonian lungfish, showing marked similarities with crossopterygians as well as stegocephalians.

That summer, Denmark had won the case against Norway in The Hague, and the general concept of ‘the four-legged fish’ – having figured as a scientific trump for Denmark – was, as Koch later explained to Säve-Söderbergh, “lifted to a level, that

19 Schuchert to Koch, 22/99-32, SASO, Correspondence K-N.20 Stensiö to Koch, 28/12-32, LK/14.

Fig. 5. Skull of Ichthyostega as depicted in Säve-Söderberg, 1932, p. 42.

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must naturally make an impression on any government.”21 In January 1934, as preliminary investigations of the new mate-rial began, Koch was able to announce publicly the find of a completely new path leading from the fishes to the higher animal classes:

A completely new four-legged fish has been found! In ‘old fourlegs’ we believed to have found a missing link between the lungfish and the tetrapods, which was epoch-making. But now it looks as though we have found a new path leading from the lungfishes up to ... well, this new thing! Therein lies a discov-ery of extraordinary importance for our whole investigation of the origin and development of life on Earth ... Therefore these investigations are supervised with all the carefulness that the outstanding professionals in Stockholm have developed in their difficult craft. No possibility will escape their keen eyes.22

‘The four-legged fish’ was by now a full-blown media star, and while Swedish newspapers reported of foreign scientists flocking to Stockholm, Koch used the sensation to further the interest of private investors, government officials and the general public.

Not all, however, were equally impressed with Koch’s sensationalist presentation of the material. When in March 1934 Säve-Söderbergh was invited to talk about his investiga-tions to the Danish Geological Society, Koch gave an introduc-tory speech, which, as one observer remarked in a letter to a colleague, “was quite funny in a way, because he in all naked-ness told us about all the rubbish he made people believe about the four-legged fish: ‘I usually equip it with four limbs and all imaginable fins, gills, lungs and everything; in Stockholm they all thought it was a scream; we had a great party up there, and so on´. Some were scandalized at his frank confessions, and despite the humorous tone in his speech, the atmosphere was strangely tense when he finished.”23 All in all, according to the same observer, the evening was a limited success: “Säve’s talk was sort of good, as it actually contained some new informa-tion, but most people lacked the qualifications to understand

21 Koch to Säve-Söderbergh, 6/4-36, SASO, Correspondence K-N.22 “Lauge Koch har hjemført ukendt hvirveldyr”, Politiken, 21/1-34.23 Milthers to Noe-Nygaard, 28/3-34, NN, Correspondence 1926-39.

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him and as he spoke very dryly, listing an eternity of names, the overall effect was quite deadening.”24

Säve-Söderbergh might well have left most of the audience in a befuddled haze, speaking as he did of a complete revolution in the conception of early vertebrate evolution, bridging the troublesome gap between the fishes and the amphibians. He was convinced that the Devonian crossopterygians (or lobe-finned fishes), lungfishes and tetrapods had so much in common, that they had to be classified together in an entirely new sub-group among jawed fishes. It was this group of creatures – named the ‘choanates’ after their internal nostril openings or ‘choanae’ – that had given rise to the amphibians, the reptiles, the birds, the mammals and ultimately to humankind.25

To be sure, Koch, not being a specialist, might have been taking a few liberties when celebrating the work going on in Stockholm and Uppsala, but notes that he made for public speeches, which are kept in his personal archives, do reveal his undisputable knack for conveying the problem to a general audience. To a high-school audience he said the following:

Let us imagine a large and widely branching tree buried during a sandstorm, with only a few twigs showing above the ground. This is roughly how we must view the animal world of today. And to understand relationships, we must scrape away the sand, to find out how the twigs join in larger branches and ultimately meet in the trunk itself [...] Collecting in Greenland, we are working in the place where the amphibian-branch and the fish-branch start to meet, that place in the history of evolu-tion, where the vertebrates first went on land and acquired legs. But here comes the surprise: the Greenland investigations have shown, we are not looking at just one family tree, but at no less than three [...] It has turned out, that what used to be seen as related, is in fact branches of the three trees tangled together [...] The amphibians, which we used to perceive as one big branch of the big family tree, do in fact belong to three different family trees.26

24 Milthers to Noe-Nygaard, 28/3-34, NN, Correspondence 1926-39.25 Säve-Söderbergh to Koch, 1/1-33, LK/14.26 Manuscript for a speech given to high-school students, undated [between 1933 and 1938], LK/14.

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Fig. 6. Diagram showing the relationships of early vertebrates and stegocphalians according to Säve-Söderbergh. From Säve-Söderbergh, 1938, p. 151. Translation of central concepts from the bottom up: gnathostomer = jawed fishes; fisk = fishes; hajlignende former = shark-like forms; aktinopterygier = true fishes; lunge-fisk = lungfishes; padder = amphibians; halepadder = urodeles; haleløse padder = tail-less amphibians; pattedyr = mammals; krybdyr = reptiles; fugle = birds.

What Koch was explaining here in relation to the amphibians was the notion of ‘polyphyletism’, which became a controver-sial ‘leitmotiv’ in the writings of members of the Stockholm School of early vertebrate palaeontology. Proponents of ‘poly-phyletism’ – in opposition to proponents of the more gener-ally accepted theory of ‘monophyletism’ – worked from the assumption that some of the derived traits shared by extant taxa have appeared separately several times. Accordingly, Säve-Söderbergh was quite convinced that the choanates had developed along at least two parallel lines of evolution: one leading to the lungfishes and the urodeles (salamanders and newts) and another leading to the lobe-finned fishes and all

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other tetrapods, even allowing for a possible further division of the tetrapods into still more lines of evolution27 [Fig. 6].

But a complete rearrangement of the system of classifica-tion in the fish-tetrapod transition was a complicated project. It required not only the comparison of available Devonian vertebrate material to develop a reliable terminology of bones and sensory canals in the skulls of different species, but also further investigations of already known related faunas in order to establish a firm foundation for discussion of specific devel-opments in the fish-tetrapod transition. So, while Koch was showing off his evolutionary sensation to politicians, patrons and the general public, Säve-Söderbergh devoted himself to stratigraphical analysis and description of other Devonian and Triassic vertebrates. He did participate in Koch’s East Greenland expeditions in 1934 and 1936, collecting much new material, but he did not add any significant comments on the Devonian tetrapods, limiting himself to brief references in a number of publications.28

Still, the sensational and transitional nature of the animal had been publicised with enough success to keep the image of ‘the four-legged fish’ on its feet, so to speak, even without the justification of continuous scientific elaboration in the labora-tory. In 1935 some of the most spectacular specimens were conspicuously displayed in the ‘Greenland wing’ of the Danish stand at the Brussels World Fair.29

In December 1935 Koch became involved in a bitter conflict with eleven of the most prominent Danish geologists of the day, among them O. B. Bøggild, director of the Danish Geological

27 Gunnar Säve-Söderbergh, “Some points of view concerning the evolution of the vertebrates and the classification of this group”, Arkiv för Zoologi, 1934. 26a/17: 1-20.28 Gunnar Säve-Söderbergh, “Further contributions to the Devonian stratigra-phy of East Greenland, 2. Investigations on Gauss Peninsula during the summer of 1933. With an appendix: Notes on the geology of the Passage Hills (East Greenland)”, Meddelelser om Grønland, 1934, 96/2: 1-74; Gunnar Säve-Söderbergh, “On the dermal bones of the head in labyrinthodont stegocephal-ians and primitive Reptilia with special reference to Eotriassic stegocephalians of East Greenland”, Meddelelser om Grønland, 1935, 98/3: 1-211; Gunnar Säve-Söderbergh, “On the morphology of Triassic stegocephalians from Spitsbergen and the interpretation of the endocranium in the Labyrithodontia”, Kungliga Svenska Vetenskapsakademiens Handlingar, 1936, 3/15: 1-181.29 Koch to Stensiö, 18/1-35, LK/16.

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Museum and the only professor of geology in Denmark, and Victor Madsen, head of the Geological Survey of Denmark. The immediate reason for this controversy was a book review submitted to the Bulletin of the Geological Society of Denmark by ‘the 11’, as Koch’s attackers was soon dubbed by the press.30 The book in concern was Lauge Koch’s Geologie von Grönland, published in September 1935 in the German handbook series Geologie der Erde.31, and the fierceness of the critique dealt out by Koch’s Danish colleagues was remarkable.

Over fifteen pages, not only Koch’s recent book but also his general scientific conduct and achievements throughout his career were met with serious accusations under headings such as: “Misunderstandings and Statements that have not been Proved”, “Misleading Argumentation”, “Suppressions and Incorrect Quotations”, “Appropriation of the Results of other Explorers” and “Absurdities and Self-Contradictions”. The review was followed by a call for an extraordinary general assembly of the Geological Society of Denmark, at which a resolution in effect excluding Koch from the society would be presented. Furthermore, 600 off-prints of the review in English were distributed to geologists throughout the world.

Considering the prominence of the attackers, and the fact that they counted among them former teachers as well as students of Koch, this critique was not to be taken lightly. After having conferred with the Director of the Greenland Administration Jens Daugaard-Jensen, Koch decided to sue his attackers for slander. The press quickly took advantage of what would become the largest public scandal in the history of Danish science and one of the most extensively documented Danish verdicts on any subject known until then. Over the next three years, “the Lauge Koch Case” haunted Danish newspa-per headlines as it moved through the Danish court system, until in June 1938, when it ended with a verdict that let both parties boast of victory. This is not the place to deal with the consequences of this painful conflict in detail. Suffice it to say

30 O. B. Bøggild, K. Callisen et al., “Remarks upon ‘Lauge Koch: Geologie von Grönland, 1935’, in Meddelelser fra Dansk Geologisk Forening, 8(5), 1935, pp. 497-512.31 Lauge Koch: “Geologie von Grönland”, in E. Krenkel (ed.), Geologie der Erde, Berlin: Gebrüder Bornträger, 1935.

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that an insurmountable barrier had been established between Koch and the geologists at the Danish Geological Museum, which prevented any form of cooperation between the parties for the rest of Koch’s life.32

To suggest that this painful situation was caused by one single book review alone would of course be absurd. Rather, the ‘Lauge Koch Case’ must be seen as an articulation of dramatic upheavals in the culture of Danish arctic geology in a period of economic crisis and serious geopolitical tension. For almost half a century the Geological Museum of Copenhagen had been the natural institutional centre of Danish geology, receiving all-important collections made on Danish expeditions for safe keeping, investigation and exchange with museums and collec-tions abroad. But from 1930 onwards, Koch, as the leader of the Danish East Greenland expeditions, had introduced a new order, taking all collections from his expeditions to a warehouse in the harbour of Copenhagen. From there he distributed the material directly to international specialists abroad, refusing repeated requests by the Geological Museum of Copenhagen to have the material handed over. Koch, enjoying considerable support from politicians, government officials and wealthy businessmen with an interest in Denmark’s arctic possessions, had been able to refuse such claims with reference to the lack of necessary scientific expertise available in Denmark. In summa-ry, then, Koch’s success and internationalism had seriously undermined the position of the Danish Geological Museum in Greenland geology, both in Denmark and abroad.

After the debacle in 1935, however, Koch’s position was increasingly challenged. The controversies between Koch and his professional colleagues in Denmark seriously marred his credibility and reputation – in Denmark much more so than abroad. Simultaneously, the Danish victory in The Hague in 1933 had lifted the sense of political urgency formerly attributed to Koch’s activities. When Jens Daugaard-Jensen, the Director of the Greenland Administration died in November 1938, Koch lost one of his most fierce and faithful political allies. Koch still maintained his position as independent consultant

32 For a fuller treatment of this controversy and its consequenses, see Ries, “Retten”, and Ries, “Lauge Koch”, 2002.

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for the Greenland Administration, but Danish claims to Koch’s East Greenland material intensified.

4. Suspended animation

In 1937, the twenty-six year old Säve-Söderbergh was appoint-ed professor of palaeontology at Uppsala University. But he was also struck by a serious lung disease, which kept him in bed for months and years on end, and seriously impeded his work. This, and the outbreak of World War II, which brought Koch’s Greenland expeditions to a complete halt between 1939 and 1947, prevented further progress in the investigation of the Ichthyostega material. Up to and during World War II, Säve-Söderbergh, writing from his sickbed, and others referred to the East Greenland material in scientific textbooks and popular books and journals. General interest in the whole fish-tetrapod transition matter was boosted by the 1938 catch off the South African Coast of the extant lobe-finned coelacanth Latimeria, a ‘living fossil’ thought to have been extinct for at least 70 million years. But owing to the limited mass of scientifically certified knowledge about Ichthyostega, most commentators limited themselves to descriptions of the skull and general considerations of the fish-tetrapod transition on the basis of other available material.33

During World War II, while Säve-Söderbergh was struggling through serious illness and surgical operations removing part of his rib cage, Koch was struggling to gain momentum after serious setbacks caused by the war, and by bitter rivalry within the Danish geological community itself. In 1939, the Danish Government decided that all vertebrate collections from Lauge Koch’s expeditions were to be transferred to the Danish

33 See e.g. Säve-Söderbergh, “På jagt”, 1937; Gunnar Säve-Söderbergh, “Drag ur den svenska vertebratpaleontologins utveckling och resultat”, Geologiska Föreningens i Stockholm Förhandlingar, 1946, 68: 352-371; Gerhard Heilmann, Universet og Traditionen, (Copenhagen, Munksgaard, 1940); Eigil Nielsen, “’Den firbenede fisk’ og andre hvirveldyr fra Østgrønlands fortid”, Dyr i Natur og Museum. Årbog for Universitetets zoologiske museum, 1943: 63-76; Johannes V. Jensen: “Amfibiet. Haletudsen og den firbenede fisk”, Arbejdernes Almanak, 1945: 25-30, Alfred S. Romer, Vertebrate Paleontology, (Chicago: University of Chigaco Press, 1933, 2nd edition, 1945).

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Zoological Museum, in an attempt to satisfy Danish claims to the material while at the same time respecting Koch’s and Stensiö’s refusal to have anything to do with the Danish geolo-gists. Still, a special arrangement was made for the Devonian stegocephalians, which remained in Sweden under the custody of Säve-Söderbergh and Stensiö.

There were at least two reasons for this. For one, Koch’s Swedish collaborators were appalled at the way Koch had been attacked by his Danish colleagues, but perhaps more to the point, the only Dane remotely qualified for working on the material was young student Eigil Nielsen, who had been hand-picked by Koch for specialized training under Stensiö. Nielsen had still not completed his education, and was currently occu-pied by studies of the vast collections of Triassic fishes brought home by Koch’s expeditions.34

In 1942 Koch’s most influential patron, the Danish prime-minister Thorvald Stauning, died. Koch’s office was moved to a location outside the Greenland Administration building itself. The following year the palaeontological collections delivered to the Zoological Museum in 1939 were moved to the Geological Museum, where Koch’s opponents had consolidated themselves in a tightly knit and very influential lobby, aiming to set the agenda for future Danish geological investigations in Greenland. But still, the Devonian stegocephalians remained in Stockholm.

Curiously, as World War II came to an end, Koch’s position at the fringes of the politico-scientific arena in Denmark began to work in his favour. At the time, Daugaard-Jensen’s successor as director of the Greenland administration, Knud Oldendow, was struggling with depression and physical illness under the burden of his new authority and the challenges of re-ordering the arctic scientific community after years of bitter conflict. According to Koch, Oldendow often came to the sanctuary of Koch’s office for comfort and advice.35

In May 1945 the German occupation of Denmark was lifted, and in July Koch’s opponents at the Geological Museum launched a small expedition to Nugssuaq in West Greenland. They also proposed to Oldendow the establishment of a Greenland Geological Survey proper – deliberately and specifi-

34 Ries “Retten”, 2003, pp. 318-29.35 Koch to Porsild, 18/6-45, RMOG/2.

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cally leaving Koch out of the picture. In the same month Koch decided to visit his colleagues in Stockholm to sketch out plans for the future. Oldendow decided to join him. According to Koch, the trip became a mixture of recreation and of discus-sion of future cooperative expeditions, and Oldendow, “who conceives of himself as a sort of amateur-ornithologist and therefore makes claim to certain scientific qualifications, took particular interest in the display of the four-legged fish.”36 To say that Ichthyostega alone swung Oldendow’s favour in Koch’s direction would clearly be an exaggeration, but the director must surely have been convinced of the importance of the unique the material. Likewise, we may assume, that Koch, Säve-Söderbergh and Stensiö in their discussions with Oldendow reiterated their complete refusal to cooperate with the poorly qualified geologists in Denmark.

Oldendow, meanwhile, decided to compromise between Koch and his adversaries. In January 1946 he approved the establish-ment of the Greenland Geological Survey (GGU for Grønlands Geologiske Undersøgelser) as suggested by the museum geolo-gists, while at the same time agreeing to financially support Koch’s initiative to resume his activities in East Greenland. Protests from the Danish geologists proved fruitless, and thus emerged a peculiar arrangement: for the next twenty-two years, two state-subsidised Geological Surveys operated independently in Greenland – Koch in the East, and the GGU in the West.37 Very little exchange or cooperation took place between the two, and the investigation and publication of findings concern-ing the East Greenland Devonian vertebrates remained on the hands of Koch and his co-operators in Sweden.

Koch’s international reputation and political skills had secured his continued existence as a leader in Danish Greenland geology after World War II, but the steady, unquestioned and undivided governmental support that he had enjoyed before the war, was lost. He now had to compete for funds with the GGU on a yearly basis. Now, more than ever, he was in need

36 Ibid.37 Very little has been published describing the peculiar situation within Danish Greenland geology during the Cold War period. One exception is Knud Ellitsgaard-Rasmussen, “En stjerne fødes – beretning om GGU’s tilblivelse”, GEUS Report, 1996, 102:1-76.

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of scientific sensations and of public attention to muster the continued support for his East Greenland activities.

Koch’s first expedition after World War II was launched in 1947. Finding people to continue the collecting of vertebrates had to be sorted out. Säve-Söderbergh, despite a slight recovery that had actually allowed him to leave the hospital in 1945,38 was still too weak for long travels, let alone for working in the field. Only two other people could be considered for the job: Eigil Nielsen and Erik Jarvik, both of whom had studied in Stockholm under Stensiö and had served as field assistants for Säve-Söderbergh before the war.

In 1942 Nielsen had defended his doctoral thesis on “Triassic fishes from East Greenland”. Stensiö, who had been on the examining committee, had high regard for Nielsen’s work, and according to him, the day had been a celebration for all parties involved.39 Jarvik had defended his doctoral thesis that same year. His work on the fossil lobe-finned (crossopterygian) fishes, which were already regarded as the possible ancestors of tetrapods, suggested that while one group of these 370-400-million-year-old fishes (the Porolepiformes) shared the same snout structure as the urodeles (salamanders and newts), another (the Osteolepiformes) shared unique snout features with other tetrapods (frogs and amniotes). The implications were clear. The tetrapods had evolved at least twice from differ-ent fish groups. To Säve-Söderbergh, who had been on Jarvik’s thesis examining committee, the thesis “provided the theory of a polyphyletic origin of the amphibians with a new and particu-larly beautiful confirmation and a much firmer foundation.”40

Both Nielsen and Jarvik joined Koch’s expedition for further collections in the summer of 1947. But still there was the ques-tion of the future of the four-legged fish. Säve-Söderbergh had not added anything of significance to its investigation since 1932, and Koch was getting anxious for something to happen. In Denmark, interest in the material was on the rise, and on the issue of funding, Koch was quite optimistic. In September 1947 he wrote to Stensiö: “I believe that the state will donate

38 Säve-Söderbergh to Stensiö, 6/8-45, SASO, Correspondance O-S.39 Erik Stensiö, autobiography (unpublished manuscript, 91 pages, 1980), Library in the Section of paleozoology Riksmuseet, Stockholm, on p. 63.40 Säve-Söderbergh, “Drag ur “, (1946).

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large grants regarding the East Greenland material, which has been so well advertised over the years.“41 Koch’s greatest worry was that Säve-Söderbergh’s protracted illness was a stumbling block to achieving the quick results so much in demand. That autumn, the whole issue gained in urgency, as Nielsen, consort-ing with the Danish journalist Ebbe Munck, aired some rather frivolous plans about collecting and selling fossils in an attempt to raise money for an East Greenland expedition of his own. In September 1947 Koch wrote to Stensiö as follows:

[Eigil Nielsen] counts on being able to find about three pieces in one summer season. These should then be sold to the Carn-egie Foundation for 20.000 Dollars, for which Munck would buy rice to be sold in Denmark. From this you may gather, that I would very much like to continue the collection of vertebrates on my future expeditions, and that I find it quite unacceptable that Denmark should begin to sell any of these stegocephalians before they are properly investigated.42

It was one thing, Koch seemed to reason, to use the precious fossils for P.R. purposes to influence state officials and possible private benefactors. It was an entirely different matter to trade them to foreigners, encroaching on the otherwise exclusive access to the material enjoyed by Koch and the Stockholm school.

Nielsen, who was now employed at the Geological Museum in Copenhagen, may not have been showing himself as the most dependable of Koch’s collaborators, but he was capable, ambi-tious and keen on taking over the Devonian stegocephalians from Säve-Söderbergh, should he not show some recovery in the near future.43 With demands and financial prospects on the rise and Säve-Söderbergh on stand-by, only Stensiö and Jarvik were active in Sweden, and Nielsen was an asset they could hardly afford to neglect. Koch, therefore, was eager to keep him on board, and to give the investigation of material related to the Devonian fish-tetrapod transition priority over all other tasks. He wrote to Stensiö as follows:

41 Koch to Stensiö, 30/9-47, LK/9.42 Koch to Stensiö, 13/9-47, LK/9.43 Koch to Stensiö, 13/9-47, LK/9.

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The crossopterygians are in good hands with Jarvik. But the question remains what to do with all the material held by Säve-Söderbergh. Of course we should not deprive him of his mate-rial right away, but on the other hand the years keep passing, without him getting any work done. One and a half year ago I visited him during a good period, and at that time he was very interested in Triassic stegocephalians of which he has quite a lot of specimens. Furthermore he is keeping the lungfish and the Devonian stegocephalians, and sooner or later the moment will come, when he will have to let go of these things. I will then suggest, that you [Stensiö] take over the lungfish, while Nielsen takes over the Devonian stegocephalians […] Before long, I hope to be able to raise money for continued collecting, and what worries me the most, is the prospect of having the funds, but not the necessary crew.44

Apparently, however, the idea of Nielsen taking over the Devonian tetrapods did not go down well in Sweden. When finally Säve-Söderbergh succumbed to his illness and died in June 1948, negotiations between Koch and Stensiö resulted in the decision that Nielsen should stick to his Triassic fishes. The Ichthyostega material was to be kept in Stockholm on ‘stand-by’ for Jarvik to take on, when he had finished his study of the crossopterygians.45

That summer, Jarvik joined Koch’s expedition on Mount Celsius. Among the specimens collected that year were two blocks containing the first known parts of the post-cranial skeleton of Ichthyostega. Work carried out back in Stockholm revealed, in one block, a tail and a well-preserved hind limb, and in the other, parts of the head, trunk and forelimb. The new material immediately aroused the interest of international scientists, and Koch set out to exploit the situation to his own advantage. In December 1948 he wrote to Stensiö:

I have informed the Danish Government, that two American palaeontologists have seen our collections in Stockholm this autumn, and that they have taken a great interest in them. I therefore said to our Prime Minister: “Preferably, we should

44 Koch to Stensiö, 30/9-47, LK/9.45 Koch to Stensiö, 8/7-48, LK/9.

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continue our collecting of vertebrates to keep the Americans out of East Greenland.” He agreed with me on this.46

Having also presented the Prime Minister with that year’s find of some promising lead deposits near Mesters Vig, Koch had high hopes for consistent state support for his own expeditions in the future. Denmark was, then even more so than now, a country of limited natural resources, and the prospects of a possible lead-mining facility in Mesters Vig was as strong a card as any to be played in the game for government support, at a time when national economies across Europe were strug-gling to recover from the effects of war.

Over the next few years, the Mesters Vig lead earned Koch steady governmental support for continued expeditions. But Koch felt the urgent need for further investigations of the Devonian vertebrate material. Nielsen was getting increasingly involved with Koch’s adversaries at the Geological Museum, who repeatedly declared that since the Devonian tetrapods had been found on a Danish expedition, they belonged in a Danish Museum, and should be worked on by a Danish scientist, more specifically by Nielsen. Koch must have feared that the mate-rial would slip from his hands while he was waiting for Jarvik to get ready. In January he wrote to Stensiö, urging him to take up the study of the tetrapods himself, while buying time with the Danish geologists by offering them a couple of casts for exhibition purposes.47

5. The twist of a limb

In June 1949 Koch announced on Danish Radio that a scientific sensation was to be expected from ongoing Swedish investiga-tions of ‘the four-legged fish’. But Stensiö never took on the material. Apparently, he was determined that the tetrapods should go to Jarvik. He, on the other hand, was busy completing his crossopterygian studies, while competing, unsuccessfully as it turned out, for the professorship in Historical Geology that

46 Koch to Stensiö, 2/12-48, LK/7.47 Koch to Stensiö, 26/1-49, LK/9.

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had opened at Uppsala with the death of Säve-Söderbergh. 48 In 1949 and 1950 Jarvik abstained from fieldwork to concentrate on completing his thesis. Gunnar Wängsjö, another of Stensiö’s disciples, took his place on Koch’s expeditions, making further additions to the collection of postcranial Ichthyostega material. In 1950 Jarvik’s crossopterygian studies were finally published.49 Koch and the stegocephalians could not be put off any longer, and in February 1951 Jarvik declared himself ready to pick up where Säve-Soderbergh had left off nineteen years before.50

The manuscript for Jarvik’s first article on the Devonian stegocephalians was submitted in time to allow him to join Koch’s East Greenland expedition in the summer of 1951. The actual publication, however, appeared only in February 1952, presenting a discussion of a range of Devonian vertebrate fossils, including fishes, crossopterygians, lungfish and all the available Ichthyostega specimens.51 Among the described specimens was a single skull of a different type of Devonian tetrapod found by Jarvik and Säve-Söderbergh back in 1933.

Most likely, it was this specimen to which Koch had referred in the newspapers back in 1934, when he announced the discovery of ‘a completely new four-legged fish’, but since then, neither Säve-Söderbergh nor Jarvik had published anything on it. Jarvik described the fossilized fragment as a separate species of tetrapod and named it Acanthostega, but with only one specimen to go on, he could not take his investigations any further. Acanthostega went back to its drawer, staying there for more than 30 years, until Jennifer Clack began investigating the creature on the basis of new and exceptionally well-preserved material recovered by her on Celcius Bjerg in 1987.

48 Stensiö, autobiography, pp. 67-68.49 Erik Jarvik, “Middle Devonian vertebrates from Canning Land and Wegeners Halvø (East Greenland). 2. Crossopterygii”, Meddelelser om Grønland, 1950, 96/4: 1-132; Erik Jarvik, “Note on Middle Devonian crossopterygians from the eastern part of Gauss Halvø, East Greenland. With an appendix: An attempt at a correlation of the Upper Old Red Sandstone of East Greenland with the marine sequence”, Meddelelser on Grønland, 1950, 149/6.1-132.50 Jarvik to Koch, 12/2-51, LK/7.51 Erik Jarvik, “On the fish-like tail in the ichthyostegid stegocephalians with descriptions of a new stegocephalian and a new crossopterygian from the Upper Devonian of East Greenland”, Meddelelser om Grønland, 1952,114(12): 1-90.

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Back in 1952, however, Ichthyostega was still the only well documented Devonian tetrapod, and Jarvik, on the basis of his investigations, was able to confirm the status of Ichthyostega as older and more closely related to the fishes than any other known tetrapods:

As evidenced by the size and shape of the skull, the shoulder girdle, the ribs and the pelvic bone, the animal was compara-tively high and narrow – probably at least 1,25 times as high as broad in the pelvic region – and on the whole fairly fish-like.52

Still, conspicuous features of the tail and parts of the vertebral column caused Jarvik to classify the Ichthyostegids as ‘true tetrapods’, well adapted to terrestrial life. Jarvik observed that there were no fin-rays on the lower side of the tail “which no doubt rested or dragged on the ground when the animal was on land or in shallow water…[which] renders it likely that the fin-rays in this part were reduced and disappeared in connec-tion with the change from water life to an amphibious mode of life.”53 Similarly, Jarvik noted, “as in other tetrapods in which the body is carried mainly by the two pairs of legs, the vertebral column and the back of the animal are more convex in lateral view than they usually are in fishes.”54

Strikingly, though, a closer inspection of the position of the hind limbs in his attempted restoration of the Ichthyostega appears to contradict his assessment of the animal’s walking abilities. In fact, his reconstruction showed the hind limbs with the toes directed backwards, in the position in which they were found.55 [Figs. 7a and 7b] While Jarvik himself confessed that his investigation of the limbs had been superficial and prelimi-nary, he still suggested that the position of the hind-limbs in the fossils “may be accidental, but it is also possible, that the foot was held in this position when the animal was swim-ming.”56 But if only circumstantial evidence seemed to support

52 Jarvik, “On the fish-like tail”, p. 21.53 Jarvik, “On the fish-like tail”, p. 26.54 Jarvik, “On the fish-like tail”, p. 21.55 Jarvik, “On the fish-like tail”, p. 84; see also Jarvik to Koch, 18/2-52, LK/7.56 Jarvik, “On the fish-like tail”, p. 18.

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his conclusions, why, then, did he insist on interpreting the Ichthyostega as a ‘walking fish’?

mangler

Fig. 7a. Photograph of one of the Ichtyostega specimens showing the tail and hind leg. From Jarvik 1952.

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Fig. 7b. Drawing of the specimen shown in Fig. 7a, and another also showing a tail and hind limb. From Jarvik, 1952.

Part of the explanation has to do with the general contemporary scientific trend in thinking about tetrapod limb evolution. Back in 1933 Alfred Romer of Harvard University, Massachusetts, had offered a compelling scenario.57 Many Devonian rocks are bright red, and in 1916 an American geologist named Joseph Barrell suggested that this coloration meant that the rocks had been baked dry in arid conditions. Inspired by Barrell’s ideas,

57 Romer, “Vertebrate”, 1933.

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Romer envisaged the Devonian ancestors of land-dwelling tetrapods as relatives of lungfish living in freshwater pools that suffered seasonal droughts. Like lungfish, they could breathe air if oxygen became scarce in the water or the ponds dried up. And some of these ancestors, Romer suggested, struggled with their fins over the harsh land to another pond. Those with more limb-like extremities were better able to struggle over dry land and more likely to reach another pool. Fish with weak fins died along the way; fish with strong ones lived to reproduce, and gradually fins turned into limbs, which are much better for overland travel. At the same time, many other parts of the body - such as eyes, ears and skin - changed to better cope with the new environment.

Fig. 8. Romer’s theory of tetrapod evoplution as illustrated by the Danish artist and palaeontologist Gerhard Heilmann. Three types of crossopterygians are vying for terrestrial survival: 1. Macropetalichthys, 2. Glyptolepis and 3. Eusthe-nopteron. From Heilmann, 1940.

The middle decades of the twentieth century, and particularly the 1950s, gave birth to many new theories on terrestrialisa-tion and limb evolution. Generally, it was agreed that because some crossopterygians had developed fins with a bone struc-

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ture like those of tetrapods, they must have used them in a similar manner. Thus, changes to the locomotive system were thought most likely to have occurred under aquatic conditions, while only the selective pressure associated with excursions onto dry land could have provoked the shedding of fin rays. Some, like Jarvik, questioned Romer’s scenario of the drying ponds, suggesting that it was the evolution of terrestrial vegeta-tion during the latter part of the Devonian that had created the necessary conditions for vertebrate colonisation of the land.58 But most scenarios were fundamentally similar to Romer’s old tale: they presented the evolution of tetrapod limbs as a response to the challenge of moving across dry land.59 [Fig. 8.]

It would be fair to say then, that Jarvik’s interpretation of Ichthyostega – in spite of the somewhat disturbing position of the animal’s hind legs – was consistent with the generally accepted theoretical framework, coupling vertebrate terrestri-alisation and tetrapod limb evolution. In fact, it was consis-tent with the image of ‘a four-legged fish’ that Koch had been pushing in the media since 1932, and Koch immediately hired a journalist to make sure that Jarvik’s publication got all the media attention it deserved.60 On 10th February 1952 an article in the Danish newspaper Socialdemokraten headlined “The sensation predicted by Lauge Koch presented to science” and reported of Jarvik’s “[...] sensational treatise on ‘the four-legged fish’ including the first depiction of the animal.”61

Meanwhile Koch, now nearing his sixtieth birthday, was haunted by sleepless nights worrying about his impending retirement and the summing up of his many years of scientific exploration in East Greenland. His lead-investigations had inspired the Danish state, in cooperation with private contrac-tors from Denmark, Sweden and Canada, to permit the newly established ‘Nordic Mining Company’ to begin commercial mining in Mesters Vig. Koch himself was detached from the operation, working only as an occasional consultant for the

58 Erik Jarvik, “Crossopterygierna och de första fyrfota djuren”, Svensk Faunistisk Revy, 1955, 3: 80-96, on p. 93.59 Jennifer A. Clack, Gaining ground: the origin and evolution of tetrapods (Indiana University Press, 2002), on p. 100.60 Koch to Jarvik, 8/2-52 LK/7; Koch to Jarvik,18/2-52, LK/7.61 “’Den firbenede fisk’ fra Grønland – en nøgle til udviklingshistorien”, Socialdemokraten, 10/2-52.

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next couple of years.62 Koch was therefore ready to renew his efforts at promoting ‘the four-legged fish’, and after another sleepless night in February 1952, he wrote to Jarvik:

Only a few years ago East Greenland remained a distant fairy-tale land, in which Norway challenged our national sovereignty (one of the greatest Norwegian geological accomplishments may well be, that their policy has eased my access to funding for my East Greenland investigations), and later influential groups looked favorably upon my continued investigations [...] Now that so much wealth is to be gained up there, the situation has changed, but of course I will never forget how ‘the four-legged fish’ has aided me in my fundraising time and again. During my delibera-tions last night I realized, that ‘the four-legged fish’ should not be allowed to become just another zoo-palaeontological curiosity in the future, and I decided to renew my efforts towards lifting the investigations to a higher level.63

To that end, Koch asked Jarvik to prepare a confidential report on the collecting work undertaken between 1929 and 1952, to be presented to possible investors and government officials. Jarvik complied, spending the summer working up the report, while stimulating public interest in ‘the four-legged fish’ through interviews and articles printed in European and American journals and newspapers.64

In December 1952 Jarvik’s report was ready for Koch to pres-ent to the Danish Government together with his plans for future investigations of the East Greenland Devonian vertebrates.65 While waiting for the politicians to evaluate his suggestions, Koch urged Jarvik to stimulate public awareness by preparing a popular scientific article on the basis of his report: “The ordi-nary Danish newspaper reader knows of the existence of a ‘four-legged fish’”, Koch wrote to Jarvik, “ but thinks that it is only a single or very few specimens.” The article, Koch suggested, should “present a picture of the number of people that have

62 Aksel Mikkelsen “Blyfundet i Mesters Vig”, Tusaat/Forskning i Grønland, 1992,3: 60-62 on p. 62.63 Koch to Jarvik, 19/2-52, LK/7.64 Jarvik to Koch, 12/6-52. LK/7.65 Koch to Jarvik, 22/12-52, LK/7. See also Erik Jarvik: ‘Devonian vertebrates from East Greenland collected between 1929-1952’, confidential report, LK/7.

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been involved in the search for ‘the four-legged fish’ over the years and of the number of specimens that have been found, while conveying – in very popular terms – the impression, that we actually know of quite a large Devonian fauna.”66

Apparently Jarvik neither denied nor complied with Koch’s request. It seems that Jarvik’s work load was growing in a peri-od of poor economy and lack of staff at the Swedish Museum of Natural History.67 In April, the Danish Government decided not to back Devonian vertebrate investigation financially. But, as Koch explained to Jarvik, there was still hope for the future: “I have now bombarded the Government with arguments to such an extent, that this morning even the Ministry of Finance believed that some extra money could be granted already this summer. Unfortunately, I have just now received a note, that the Prime Minister (under whose jurisdiction I am) because of the uncertain political situation and several General and Public Elections etc., will not risk increasing my expedition budget until next year.”68

Towards the end of the year, things began to look up, and just before Christmas, Koch was able to promise Jarvik and a couple of his assistants participation in his next expedition.69 Jarvik, on his part, had found time to work on the popular scientific article requested by Koch, and in January 1954 he reported his progress to Koch, asking for assistance:

No harm could probably come from cheering up the article by reproducing the first reconstruction of a four-legged fish ever published – to my knowledge, at least. It was done by Storm-Petersen [Danish cartoonist] and published by some Danish newspaper, probably around 1932-34. It shows some pipe-smoking cavemen riding four-legs. Even if it is a bit anach-ronistic, I still believe that such images will draw more atten-tion, than our own more correct but less lively attempts at a reconstruction. Is it possible to get hold of a good copy of this picture so that it can be reproduced, and is that allowed?70

66 Koch to Jarvik, 27/1-53, LK/7.67 Jarvik to Koch, 28/4-53, LK/7.68 Koch to Jarvik, 8/4-53, LK/7.69 Koch to Jarvik, 23/12-53, LK/7.70 Jarvik to Koch, 9/1-54. LK/7. Jarvik is mistaken on the dating of the picture here. It was first published in 1943 in the Danish newspaper B.T. (Jarvik, 1996, p. 5).

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Fig. 9. Storm Petersen’s cartoon of ‘the four-legged fish’ which inspired Jarvik’s 1955 reconstruction.

For whatever reason, S t o r m - P e t e r s e n ’s reconstruction [Fig. 9.] was not included in Jarvik’s article, which appeared in the popu-lar scientific journal Scientific Monthly in March 1955.71 In its place was a new recon-struction by Jarvik [See Fig. 2 on p. ?]: the very same reconstruc-tion, that would become standard refer-ence for the next four decades, and with which Clack, Ahlberg and Blom juxtaposed their own 2005 version [see Fig. 1 on p. ?].

Jarvik’s 1955 reconstruction is quite similar to his 1952 version. But in the position of the animals hind-legs, it resembles Storm-Petersen’s image. This fish was clearly made for walking, and corresponds much more closely with the description in Jarvik’s 1952 publication, than does the original reconstruction. But the question remains why Jarvik decided to twist the hind legs of his Ichthyostega around, in spite of his comment in 1952, that he had depicted them ‘in the position they have in the fossils’.

A letter from Jarvik to Koch sent in May 1954 shortly before Jarvik’s submission of his article indicates that investigations of the skeleton of the hind legs were still very preliminary, and not at all ready for publication:

At last I have completed my popular article on the four-legged fish, and will submit it in a few days. I have paid much atten-

71 Jarvik, “The earliest tetrapods”, 1955. An amended Swedish version of the ar-ticle appeared in Swedish the same year: Erik Jarvik “Crossopterygierna”, Svensk Faunistisk Revy, 1955, 3: 80-96.

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tion to the illustrations having produced amongst other things a reconstruction of the whole skeleton and a new reconstruc-tion of the whole animal with skin [...] Apart from this I have worked much on the description of the skeleton of the extremi-ties, a subject which, judging from the letters I have received, attracts considerable attention. Most likely another two years will pass before I can complete that article.72

Jarvik’s article on the extremities was never finished. After 1955 he turned again to his Devonian crossopterygians and the defence of the controversial theory of the polyphyletic origin of tetrapods. The Ichthyostega material remained in the Swedish Museum of Natural History under Jarvik’s custody, but publi-cation of the fossils was brought to an almost complete halt for another forty years.

6. The re-petrification of the four-legged fish

Charting the fate of Ichthyostega between 1955 and 2005 falls beyond the scope of this article. Still, a few remarks can be made to sketch out the general situation.

Towards the end of the 1950s, Lauge Koch rapidly lost political and monetary support for his East Greenland expedi-tions. Jarvik and a couple of colleagues – Sven Erik Bendix-Almgreen and Hans Bjerring - were able to join his expeditions in 1955 and 1956, but after this Jarvik stayed at home while Almgreen and Bjerring joined Koch’s last expeditions in 1957 and 1958. From then on, Koch was able to raise money only for publication of previously collected material.73 These new restraints might well be expected to have increased Koch’s demands on Jarvik for a quick publication of Ichthyostega, but curiously quite the opposite seems to have happened.

As Koch started to drift toward the margins of Danish Greenland geology, the staff at the Danish Geological Museum eyed the possibility of re-acquiring from Stockholm the Devonian collections from his expeditions. In October 1959, Koch wrote to Stensiö: “As you know, the material belongs to the Danish

72 Jarvik to Koch, 25/5-54, LK/7.73 Koch to Stensiö, 7/10-59, LK/9.

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state, and while I am still alive, we should make sure, that even if the collections must in time return to Copenhagen, it will be up to Jarvik to describe it.”74 In December Koch raised the issue again, this time with Jarvik, who was taking over the profes-sorship in palaeozoology upon Stensiö’s retirement that year. “I was discussing other matters with the State Secretary”, wrote Koch, “and I brought up the question [of ‘the four-legged fish’] and said that one day when I am gone, the Geological Museum will probably attempt to acquire the material, and I said that this could not be done until it was published.”75 If Koch would have his way, the material should stay in Stockholm until Jarvik had made a full description of the animal.

Jarvik seemed to agree. Ichthyostega was still the earliest known tetrapod, a palaeontological prize of considerable scientific potential. He may have been busy enough with his crossopterygian investigations, but still he was not prepared to let the four-legged fish slip away. In 1960 the Danish Geological Museum was planning to open an exhibition of Greenland fossils in conjunction with the International Geological Congress to be held in Copenhagen that summer. In March, Eigil Nielsen approached Koch for a possible loan of some of the East Greenland stegocephalians. Koch wrote of the meet-ing to Jarvik: “[Nielsen] said: We do have a lot of Devonian material to exhibit, but no four-legged fish. I promised to write you immediately, and said that it might be possible for him to borrow one or two specimens of the four-legged fish.”76

But Jarvik did not think so: “Regarding the exhibition at the Geological Museum, it is my interpretation that we are dealing with a more permanent exhibition, and not one to last only for the duration of the congress. In that case it is difficult to know what to do, since practically all the material we have is needed for continued investigation.”77 The Danes were granted a couple of casts and some photographs, but the originals stayed in Stockholm. And so they did for another 36 years. Koch retired in 1962 and died in 1964, leaving Jarvik with almost

74 Koch to Stensiö, 7/10-59, LK/9.75 Koch to Jarvik, 22/12-59, LK/7.76 Koch to Jarvik, 28/3-60, LK/7.77 Jarvik to Koch, 6/4-60, LK/7.

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unlimited control of the four-legged fish. As long as he did not finish his investigations, the creature was his for keeps.

But among Jarvik’s colleagues, his Ichthyostega was viewed with growing distrust. During and after the 1950s Romer’s theory, that the development of limbs in Devonian crossop-terygians was a response to the challenge of venturing onto dry land, was increasingly contradicted. Romer’s theory was founded on the idea that the rocks, in which the Devonian cros-sopterygians and tetrapods had been found, were red because they had been baked in the sun during seasonal droughts, and Jarvik’s version of a terrestrial Ichthyostega seemed to support Romer’s theory. But in 1957 R. F. Inger (1957) made a strong case against this scenario by arguing that the Devonian redbeds in which many early sarcopterygians had been found had formed in environments that were hot (tropical or subtropi-cal) but not necessarily seasonally dry.78 Over the years, several researchers corroborated this idea, suggesting that many of the sediments constituting the Devonian redbeds were deposited in marine, coastal or estuarine environments.79

Gradually, the once so influential ‘Stockholm school’ of early vertebrate palaeontology was beginning to lose international credibility. In the general context of evolutionary systemat-ics arising in the 1940s and 1950s, the polyphyletic theories of Stensiö and his followers had increasingly been viewed as heretical. Jarvik’s rejection of the new trend of phylogenetic systematics (cladistics) in the 1960s only increased his scien-tific isolation. In later years international colleagues often vividly expressed their opposition to Jarvik’s unusual ideas about early vertebrate evolution at meetings and conferences. He rarely replied in public, preferring to publish his arguments years later in thoroughly argued papers or monographs.80

In 1964 a government decision threatened to rob the depart-ment of Jarvik’s professorship, a move that was only prevented by a flood of protest letters, gathered by Jarvik and Stensiö

78 Inger, R. F. (1957), “Ecological aspects of the origins of the tetrapods”, Evolution, 11: 373-376.79 Laurin, Meunier, Germain and Lemoine (2007), “A Microanatomical and Histological Study of the Paired Fin Skeleton of the Devonian Sarcopterygian Eusthenopteron Foordi”, Journal of Paleontology, Vol. 81, Issue 1: 143–153 80 Janvier, P. (1998), “Erik Jarvik (1907-1998). Palaeontologist renowned for his work on the ‘four-legged fish’”, Nature, 1998, 392: 338.

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from specialists around the globe. Quite strikingly though, in most cases, the argument for a continuation of the professor-ship were made in reference to achievements made prior to World War II.81 Jarvik’s professorship was saved, but by the time he retired in 1972, early vertebrates had become only a marginal occupation of the Department of Zoo-palaeontol-ogy at the Museum of Natural History in Stockholm. Hans Bjerring, Jarvik’s friend and long-time colleague in Stockholm, recalls the situation:

When [Jarvik] retired, he had a drawer with some Greenland material, which he studied and published a paper about [...] After he finished, he said: “What the hell, Bjerring, nobody takes an interest in what we are fiddling with.” And then the idea arose in his mind – and I supported him, stimulating it to make him completely familiar with it – that he should write a book. [...] He wrote that book during the 1970s, and I was in contact with him every day. He chiefly talked to me about his work. With the others at the department, it was just ‘hello’ and ‘good bye’. There was never any conversation that way. And that suited him fine.82

In 1980 Jarvik published his Basic Structure and Evolution of Vertebrates. Vols. I & II, summing up his controversial ideas. [Fig. 10. ] General remarks on Ichthyostega are found scattered throughout the text, but still no monograph on the mysterious creature had been published by Jarvik or by anyone else.

81 The complete set of letters is kept in a separate folder in Stensiös’ Archive at The Royal Swedish Academy of Sciences in Stockholm.82 Interview with Bjerring, 18/5-05.

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Fig. 10. Jarviks depiction of the polyphyletic origin of tetrapods from two differ-ent types of crossopterygians. Here taken from an article in a Swedish popular scientific journal, Jarvik, “Härstammer vi verkligen fråan fiskarna?” [Are we really decended from the fishes?] Zoologisk Revy, 1961, pp. 5-11. The Swed-ish caption reads: Man and most other four-legged animals are descended from Devonian ‘toad-fishes’ (Osteolepiformes), while the urodeles have evolved inde-pendently from another group of fishes (Porolepiformesi). Note that Ichtyostega is depicted as a ‘blind alley’ in the evolution of tetrapods. This idea, which is commonly accepted today, may have contributed to Jarvik’s reluctance to work on the animal, since his primary interest was to find the link(s) between fishes and modern tetrapods.

In 1985 Hans Bjerring, after having acquainted himself with the roughly 250 available specimens of Ichthyostega, published his own reconstruction of the creature suggesting that it was

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aquatic and hardly able to walk on land.83 [Fig. 11] According to Bjerring, Jarvik simply ignored his reconstruction:

“Jarvik was special”, Bjerring remembers. “Once he had formed an opinion, it was almost always difficult to get him to change his mind. You had to have very strong arguments. [...] He had his crocodile-like Ichthyostega. There it stood – stiff – in profile. He said nothing. He has never commented on my reconstruction. He had his reconstruction. He had the skeleton from the side.”84

While Bjerring’s aquatic reconstruction of Ichthyostega gener-ally received very little attention, Jarvik’s image of a terrestrial ‘four-legged fish’ retained its iconic status until the mid-1990s.

But pressure was slowly building up on Jarvik. According to Jennifer Clack, who by the mid-1980s was beginning to take and interest in early tetrapod evolution, “[...] it was a delicate situation at the time”:

[Jarvik] had been working on Ichthyostega since the thirties and forties, and he hadn’t really completed the work. He had come out with one or two publications – one big one which described the tail, and very little else. He’d been sitting on this stuff. It’s not that he wouldn’t let anyone else look at it, but they weren’t at liberty to publish anything on it. One respects other people’s territories, and that was regarded as his.85

83 Hans Bjerring, Facts and thoughts on piscine phylogeny, pp. 31-97 in Foreman, R.E.; Gorbman, A.; Dodd, J.M.; Olsson, R. (eds.), “Evolutionary Biology of Primitive Fishes”, Plenum Press, New York 1985. See also Hans Bjerring, “Armar och ben i utvecklingshistorisk belysning”, Fauna och flora (Stockholm) 1988, 83: 58-74. Another version of the same drawing, but without external gills, was published in Hans Bjerring Svalg- och gälspringor. Deras ursprung och vidare öden, pp. 131-140 in Kjell Ebgström (ed.) ”Naturen berättar” (Naturhistoriska Riksmuseet. Stockholm, 1989) A different reconstruction showing Ichthyostega swimming under water was published by Klembara in 1991: Jozef Klembara “Nové poznatky o najstarsich stvornozcoch”,Vesmir, 1991, 70: 88-91, 84 Interview with Bjerring, 18/5-05. Interestingly, Bjerring’s article is included in the bibliography of Jarvik’s 1996 Ichthyostega monograph.85 Quoted from Carl Zimmer, At the waters edge: fish with fingers, whales with legs, and how life came ashore and then went back to the sea (New York: Touchstone, New York, 1998) on p. 50.

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Fig. 11. A more aquatic Ichtyostega as suggested by Bjerring. From Bjerring, “Armar och ben i utvecklingshistorisk belysning” [An evolutionary perspective on arms and legs], Fauna och Flora, 1988, p.72.

Jennifer Clack’s chance came in 1987, when she managed to get permission for her, her husband Rob and Per Ahlberg, then a graduate student at Cambridge University, to join a Danish team going back to the region for the Greenland Geological Survey. In that season, not only remarkably well-preserved material from several Acanthostega individuals – among them one complete skeleton - but also new Ichthyostega fragments were recovered from Celsius Bjerg.

Over the following years, investigations of the new material revealed Acanthostega as a Devonian tetrapod that had prob-ably never left the water.86 Its four limbs were relatively long, but ill suited to support its weight. It had well developed fingers

86 See e.g. Coates, M. I. and Clack, J. A., “Fish-like gills and breating in the earli-est known tetrapod”, Nature, 1991, 352: 234-236; Clack, J. A. and Coates, M. I., “Acanthostega – a primitive aquatic tetrapod?” in Arsenault, M., Leliévre, H and Janvier, P. (eds.) Proceedings of the 7th International Symposium on Lower Vertebrates, Bulletin du Muséum National d’Histoire Naturalle, Paris, 1995: 359-373. Jennifer Clack’s web-page on Acanthostega can be found at http://www.tol-web.org/Acanthostega. For a popular account of the early work on Acanthostega cf. Zimmer, C. “Coming onto the land”, Discover, 16, 1995: 118-127.

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and toes, but no wrists or ankles. It had a hipbone, which fishes lack, but it was too weakly attached to the spine to be able to support much weight. The spine was well suited for swimming motions, but hardly able to support any weight. Its short and thin ribs would have been incapable of protecting and support-ing internal organs when affected by gravity on dry land. The tail, bearing a large bony fin, was clearly used for swimming. And while it did have lungs, it also had internal fish-like gills.

But the fact remained, that alongside all the fish-like charac-teristics, Acanthostega did have legs and feet, rather than fins. Since it was essentially contemporaneous with the apparently more terrestrial Ichthyostega, a possible explanation for its contradictory anatomy was that Acanthostega had once come onto the land, but had subsequently returned to the water, gradually losing the skeletal features needed for life on land. But the internal fish-like gills on the creature seriously contradicted this theory. All amphibians that returned permanently to the water developed external gills – feathery tissue extending out from the body as seen in some present-day salamanders. But Acanthostega still breathed like a fish, the strong implication being that Acanthostega was a tetrapod evolved from fish in the water for a life in the water.

Faced not only with Acanthostega and the challenges it posed to traditional ideas about the evolution of limbs as a response to a more terrestrial life-style, but also with a new independ-ent stock of Ichthyostega fossils, Jarvik was left with only two options: publish his Ichthyostega, or throw in the towel, and let the fish-tetrapod transition pass to a younger generation of researchers. Jarvik decided to publish. Slowly and painstak-ingly he worked on his manuscript until in 1995, at the age of 88, he suffered a crippling stroke. By then he had finally completed the bulk of a 200-page manuscript, which, with the loyal assistance of Hans Bjerring, was organized, prepared and published in 1996 with a reconstruction of Ichthyostega simi-lar to Jarvik’s 1955 version in almost every detail.87

After Jarvik’s death in 1998, the material that had been his for nearly 50 years, was finally handed over to the Danish Geological Museum in Copenhagen. Ironically, it was

87 Erik Jarvik ,“The Devonian tetrapod Ichthyostega”, Fossils and Strata, 1996, 40: 3-213.

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immediately sent to the University Museum of Zoology in Cambridge, England, where Jennifer Clack, Per Ahlberg and lately also Henning Blom have been reassessing it since, yield-ing in 2005 a Ichtyostega distinctly more aquatic than Jarvik’s ‘four-legged fish’.

7. Concluding remarks

‘The four-legged fish’ was first brought to life in the geo-politi-cal turmoil concerning East Greenland in the 1930’s. Prompted by Norwegian claims to parts of the Danish colony, the Danish government mustered considerable political and economic support for Lauge Koch’s expeditions, expecting in return sensa-tional scientific results that would swing international opinion in Denmark’s favour, and convince the International Court in The Hague, that Denmark made good use of its Arctic possessions.

The find of a Devonian tetrapod was exactly the kind of thing that was needed. Having it worked over by experts at Stensiö’s world-renowned Department of Palaeobiology at the Swedish Riksmuseum only served to boost the sensa-tion. But while Ichthyostega seemed to promise answers for important and difficult questions about tetrapod evolution, the material was still too sparse and unique for Säve-Söderbergh to feel completely comfortable about it. He therefore saved Ichthyostega for later, and turned towards other material in an attempt to establish a wider foundation for understanding fish-tetrapod relations. At this point, scientific investigation lagged behind while Koch, for political as well as financial reasons, eagerly and liberally promoted the sensation as the catchingly named ‘four-legged fish’.

Up to and during World War II, the context for scientific investigation of Ichthyostega changed in a number of ways. The Danish victory over Norway in The Hague lifted the political urgency formerly attributed Koch’s activities. At the same time, Koch’s success and lack of consideration for his Danish colleagues spawned frustration and hostility against him, culminating in the ‘Lauge Koch Case’ and seriously weakening Koch’s position. Shortly after, the outbreak of World War II and the German occupation of Denmark put a stop to all Danish Greenland expeditions, and to the otherwise steadily growing stock of

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Ichthyostega material in Stockholm. Further impediment was caused by the protracted illness – and subsequent death – of Säve-Söderbergh. With no further progress being made, Danish claims to Koch’s collections were more easily justified. It was only Stensiö’s uncompromising refusal to let go of the tetrapods that prevented them from ending up in Copenhagen.

After World War II, Koch – despite the setback experienced during the war – managed to restart his expedition activities. Still, faced with the competition from the newly founded Greenland Geological Survey, Koch had to work harder to secure political and economical backing. Again, Koch turned to Ichthyostega. But while he had some success in raising money for continued collecting, the situation in Sweden was less than favourable. After Säve-Söderbergh’s death in 1948, Stensiö insisted that the material should go to Jarvik, who was still preoccupied with his crossopterygians. In Denmark Eigil Nielsen, now employed at the Geological Museum in Copenhagen, was being pushed as a real and well-experienced candidate to taking over the tetrapods. Koch therefore needed results to justify the continued lingering of the material in Stockholm. The pressure that had been building upon Jarvik could not be ignored for long, and in 1952 Jarvik – although somewhat contradicted by his own observations – confirmed the idea of the animal that had been pushed by Koch since it was first discovered 30 years earlier: a fish that could walk on land, as well as live in the sea.

By then Koch was beginning to drift towards the fringes of Danish Greenland exploration. Still eager to sum up his many years of East Greenland exploration, he again urged Jarvik to publicly promote ‘the four-legged fish’ as a draw for continued expedition support. It was as a response to this request that Jarvik made his revised 1955 popular scientific reconstruction of the standing Ichthyostega, not on the basis of new investiga-tions of the limbs, but rather in order to meet Koch’s demand for publicity.

But the scheme to re-launch ‘the four-legged fish’ as a magnet for political and financial interest met only limited success, and in 1958 Koch was forced to terminate his expedition activi-ties for good. From then on, the pressure on Jarvik was lifted by Koch, who now seemed more concerned with keeping the fossils away from the Danish geologists than with getting the

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work done. Jarvik, accordingly, gave up on Ichthyostega to pursue his interest in the crossopterygians, and when Koch died in 1964 Jarvik was left in complete control of the material. As long as Ichthyostega remained the only known Devonian tetra-pod, no one could challenge his interpretation, however feeble its foundation might have been.

Jarvik’s reconstruction of Ichthyostega was influenced by many factors, but not by an overwhelming amount of scientific evidence. In fact, his alteration of the position of the hind limbs in 1955 was based mostly on circumstantial evidence, and in direct conflict with observations made by himself in 1952, and later verified by Ahlberg, Clack and Blom in 2005. Generally speaking, Jarvik’s Ichthyostega was well suited to common mid-twentieth-century notions of a causal relation between limb evolution and vertebrate adaptation for terrestrial life. More specifically, however, it was the durability of ‘the four-legged fish’ as popular scientific icon, the long-winded investigative process and Koch’s constant demand for scientific justification that set the frame for Jarvik’s interpretation of Ichthyostega as the first vertebrate ever to have walked the land.

Documents

2007 - Ries, CJ - Inventing the four-legged fish (Ideas in History)