The Great Fossil Enigma (21 page)

The growing use of acids in the 1950s revealed, to widespread surprise, that limestones could be extraordinarily rich in conodonts. The prewar belief that conodonts were preferentially associated with shales had been another illusion.
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No-one had reflected upon, and few knew about, John Smith's earlier assertion that limestones might be a rich source of these fossils, nor had they considered that Smith's fossils had been leached out of these rocks as a result of the natural acidity of rainwater.

With the introduction of acid preparation, the conodont took on a new ubiquity: “With just a bit of preparation, almost any marine rock of Paleozoic or Triassic age, from almost anywhere on earth, will yield to the patient investigator an assortment of phosphatic microfossils termed conodonts.” It was no longer necessary to trust in intermittent samples as complete temporal sequences could now be studied. This gave the conodonts a huge advantage over fossils which relied on the use of eye, hand, and hammer. It was now possible to collect conodonts in their thousands.
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Heinz Beckmann read Branson and Mehl's account of the use of acetic acid and improved upon the technique, thus making it possible to use less acid yet achieve more rapid digestion of samples. Published in 1952, this work had a huge impact on German paleontologists.
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After reading it, Müller offered to use acetic acid to extract the Silurian fish scales Gross was studying. Gross, who had published several large monographs on these fossils, had always extracted these scales using needles. Gross agreed to a trial and gave Müller a piece of his limestone.
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Müller returned with the residue, from which Gross picked out fish scales. But as he picked, he also found conodonts.

Like Pander, Gross came from that part of Europe we know today as Latvia; and like Pander, he too was an ancestral German. In 1925, when in his early twenties, he had moved to Marburg in Germany to pursue his career in the company of the slightly older Otto Schindewolf. Distinguishing himself in the 1930s in microscopic studies of the structure of the hard tissues of fish, Gross's work was very much in the Pander tradition. These studies naturally took him to consider the microscopic structure of those would-be-fish, the conodonts, for the first time in 1941. Unknown to Gross, Hass was at that time undertaking identical investigations in the United States and making discoveries similar to those Gross would make in Germany. Gross, however, was handicapped by the war, which made publication and wider communication impossible. His research was cut short, and from 1943 he found himself a soldier, then a prisoner, before finding relief from both in the countryside after the war. Only in 1949 did he join the university in Berlin, where he replaced his friend Schindewolf and found himself in the company of the recuperating Müller.
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The material Müller had extracted for him now provided the basis for a new paper on conodonts. Having now read Hass's study, and spurred on by the American's weakening of the American fish, Gross set about destroying the German one. He did so emphatically. He confirmed that the conodont fossil lacked a true pulp cavity and he refuted Beckmann's claims for a dentine-like structure. Nor did he find enamel. The conodont fossil was neither the tooth of a fish nor the grasping apparatus of a worm. It was not part of a gill apparatus or mandible, and it was not composed of bone or cartilage.
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Indeed, it didn't appear to belong to an internal skeleton at all. If it reminded him of anything, it was the phosphatic external armor found in some Devonian fishes, though even here there were differences. The conodont elements must have grown, he thought, by the addition of layers at the surface. That surface, then, must have been beneath a protective secretive layer, certainly during growth, and perhaps always. In the most thorough zoological comparison to date, Gross could only conclude that the conodonts “perhaps belong to a special branch of the chordates or jawless vertebrate animals.” He could certainly see structures that reminded him of other vertebrate animals, but so much was different about them. He could not place them with any known group of animals.

A few years later, Gross produced the first detailed description of the “basal structure” of the conodont, a component that had largely been ignored. He revealed that an extraordinary cone of material, composed of lamellae, sometimes extended well beneath the conodont element as commonly understood. It appeared to grow by additions inside the large cavity of the base such that the cavity might become completely filled. Unknown to Gross, the young Maurits Lindström, in Sweden, had published something similar two years earlier but had done so in a journal so obscure that no one had seen it.
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Gross took his work on the base a little further in a paper in 1960. By that time the argument was being conducted on points of extreme detail.
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The base and the crown were then to be understood as a single continuous unit, with the crown – the conodont fossil of common understanding – being more significantly mineralized.

In a few short papers, Walter Gross completely altered the zoology of the conodont. Delivered with Gross's considerable scientific authority and building upon the doubts of Hass, it tore the conodont fossil out of the mouths of fish and worms. Now it was even more incomprehensible. So original, meticulous, and convincing was Gross's work that it cast a long shadow. In the 1960s, few would consider the nature of the animal and almost no one thought of these fossils as teeth. Those who might wish to dissent knew they would need better material and improved technologies. These did not arrive for a decade.

Few paleontologists shaped the fossil so fundamentally, but Gross was not to become a conodont worker. This was just an excursion by a specialist in fossil fishes who effectively swept the conodont out of his field of concerns. Gross remained in East Germany for a while but became an increasingly outspoken political dissident. Schindewolf orchestrated his “escape” to the West and to Tübingen in the early 1960s just as the Berlin Wall went up.

Müller was not particularly impressed by Schindewolf, who had risen to become the leader of German paleontology after the war. He favored other candidates. He had remained in the east of the city after the war, undertaking his doctorate research on the cephalopods of the Devonian of Thuringia in East Germany. But when he stood for examination, the university's Soviet-controlled authorities told him that he would also need to write on communism. The very idea was an anathema to him. Fortunately, just as the Soviets were inflicting their politics and ideologies on the old university, plans were being developed to erect the Free University in the west of the city. Now, with the aid of professors in both universities, Müller escaped, in what was still merely a bureaucratic exercise, to the west of the city.

At his new department at the Free University, Müller was given a small position, but he was already suffering from acute tuberculosis of the kidney. It was simply the next in a series of diseases that would affect his life. Müller was so stressed by the urgent need to get his PhD finished that his doctor found him unresponsive to treatment. “How long do you need to finish your thesis?” his doctor asked. Müller said, “Three days.” When those three days were up, Müller returned to the hospital and spent the next year there, before leaving the “flatlands” to recuperate in the Alps, in the manner of Hans Castorp in Thomas Mann's famous prewar novel
The Magic Mountain.
At the insistence of his wife, Eva, who was always his voice of reason, Müller eventually left his retreat to return to the life of a geologist. He did so reluctantly.

Conodonts had still not entered his thinking, and back in West Berlin, he was a geologist trapped in a half-city surrounded by the communist “East.” His research sites in Thuringia might just as well have been on another planet; he had no chance of collecting there now. Out of desperation, he took the remaining samples of limestone left over from his PhD work and dissolved them in acetic acid. In them he found hundreds of conodonts, and from these he published his first conodont paper in 1956. In the middle of writing it, he traveled to Iowa, the new U.S. capital of conodont studies. It was not his intention to stay there, for he had wanted to tour the country, but his active tuberculosis, the offer of free medical support, and the wise counsel of his wife, meant he remained in the one spot. There he spent two years in the company of Miller and Furnish and wrote his own summary of conodont studies.
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It was a paper, like other contemporary accounts, that showed the conodont to be a vehicle for creative thinking. Of all the fossils, it seemed open to new views and new solutions. There were no senior workers to control or constrain thinking, or maintain orthodoxies.

In his review, Müller recognized that the rapid evolution of the platform elements – so useful to Branson and Mehl – provided the key for identifying and naming whole animals because it was these elements which distinguished them. One did not need whole assemblages to name whole animals, he thought. The approach had worked with fossil mammal teeth, so why not conodonts? Müller admitted to the subjective decisions paleontologists needed to make to document evolution but nevertheless believed it was possible and preferable to construct a natural rather than a utilitarian system, even if using isolated elements. However, even among the new generation there were those who disagreed. The young Lindström remained attached to the old ideals of the stratigrapher: “The object of the classification of isolated conodonts could not be to expound phylogenetic relationships between the different kinds of conodonts. Classification of isolated conodonts rather has to restrict its aims so as to provide the worker concerned with conodonts, especially in the field of stratigraphic geology, with clearcut morphological categories.”
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In 1956, the physically weak Müller felt empowered as the conodont world was remade with acids and new thinking. Having written his thesis on Devonian cephalopods, he now felt he might be the person to tame the European Devonian using the conodont's newfound ubiquity. He was, however, unaware that many other German minds were thinking similar thoughts, for he was isolated from his compatriots by illness, politics, and travel, as well as his preference for lone working.

Müller had no knowledge of what had been happening at the ancient University of Marburg. Here, in 1949, Beckmann had demonstrated that Branson and Mehl's contentious but wonderfully useful Grassy Creek conodonts could be found in Germany. As his rocks were rather better studied, Beckmann could now confirm that the Grassy Creek was not only Upper Devonian in age but that it occurred in the lower part of that division. Beckmann's paper on acids followed, in 1952, and then, in the spring of 1953 at a meeting of the Deutscher Geologischer Gesellschaft (German Geological Society) in Dillenburg, he revealed the true potential of the conodont for the high-resolution stratigraphic study in the German Devonian and Lower Carboniferous. The impact on his audience was immediate. A magical solution that overcame supposedly “unfossiliferous” strata and the patchy distribution of other fossils seemed to manifest itself before their eyes. The conodont was ubiquitous, could be processed with little effort, and opened up the possibility of studying rocks on a centimeter-by-centimeter scale. Exploiting fine and increasingly well studied German rock sequences, this audience imagined that a dedicated conodont worker might “influence biostratigraphic interpretations throughout the world.”
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Beckmann had fired a starting gun and a new generation rushed forward.