The Great Fossil Enigma

by Simon J. Knell

  Eichenberg's fish acquired more flesh four years later when forty-one-year-old paleontologist Hermann Schmidt acquired some quite remarkable fossils. Schmidt had actually found his first example of these new fossils a few years before, in a brickyard near Hemer in Westphalia. It showed conodont elements in close association, but the specimen was so poor that he thought no more about it. Then a collector showed up with a similar fossil. It had come from the same rock at the base of the Upper Carboniferous, but from Arnsberg, more than fifteen kilometers distant from Hemer. Perhaps these were not chance occurrences? Schmidt returned to the quarry in the spring of 1933, doubtless looking a strange sight as he systematically examined the bedding planes with a magnifying glass. The effort paid off, and in time he located nine specimens showing conodont elements in groups. In some of these the elements themselves were preserved, but in others all that remained were impressions of them in the rock. Most of these groups of fossils were surrounded by a dark patch of bitumen enrichment that he interpreted as decayed tissues of the animal. This meant, of course, that the association was natural; these elements had once occurred together in the body of a single animal.15

  On closer examination, Schmidt discovered that there was a consistency to the grouping of the different element types; some groups were in complete disarray, but others showed a repeated arrangement, which gave a clue to their relative positions in the living animal. Schmidt attempted a reconstruction – the first time anyone had tried to do this – by interpreting the arrangement he saw on the bedding planes but always with Eichenberg's functional arrangement of the different parts in mind. His was not to be an original interpretation but an extension of the German model. This suggested that a pair of strong, bladelike conodonts acted as mandibles, each showing signs of having grown in close relationship with the other. Behind the mandibles, which “seized and cut,” sat a pair of “spiky” elements that pointed forward as if to cause mortal injury to the prey. Behind these were the most numerous group of elements – slender, comb-like forms Schmidt interpreted as components of the gill apparatus (figure 3.1). For Schmidt the conodont animal was a fish even before he began his reconstruction. Of this he was already sure. He even considered the possibility that a fish fossil found in the same bed might actually be the owner of this assemblage. The head of that fish, however, had not been preserved.

  3.1. Schmidt's fish. Schmidt's reconstruction of the conodont apparatus closely mirrored the arrangement of the fossils in his fine natural assemblages. So perfectly did this seem to fit the anatomy of Eichenberg's conodont fish, he had no difficulty producing this three-dimensional model. In this drawing, the jaws are on the left and the gills on the right. From H. Schmidt, Paläontologische Zeitschrift 16 (1934). © Verlag von Gebruder Borntraeger.

  Schmidt reported his finds to a meeting of the German Palaeontological Society, the Paläontologische Gesellschaft, in September 1933, publishing a fully illustrated account the following year. Like Eichenberg, he gave his assemblage of conodont elements a single name drawn from one component, Gnathodus integer. In doing so, he claimed that there were far fewer true species of conodont than the Americans believed. His findings added weight to the German call for Americans to abandon their simplistic taxonomy and group together conodonts from the same stratigraphic horizon, giving them one name and recording the frequency of each type found. It was not simply Eichenberg's anatomical model that suggested this but also Schmidt's photographs, which spoke convincingly of the natural association of the different parts. Anyone picking up the paper would have seen this; it required no proficiency in German. The animal itself had left its own visual argument, and one just as powerful as those constructed by Hinde, Rohon and Zittel, and Macfarlane. Schmidt's associations preserved exactly the same mix of forms Eichenberg had found, and while they demonstrated that Hinde's Polygnathus dubius possessed too many conodont elements to be the remains of a single animal, that specimen did contain elements in the same proportions as Schmidt and Eichenberg had found. What none of these associations possessed, however, were those simple teeth Pander had discovered in such profusion in the older rocks. Now Schmidt wondered if these had come from an entirely different animal.

  In a few short pages, and some remarkably convincing figures and plates, Schmidt proposed a revolution in the way conodont workers should consider their subject. To German eyes, at least, progress was being made: The American fish had now been given a German apparatus and had become rather more biological. The results were in many respects conclusive, but was it already too late to change the American way of doing things? In 1933–34, the American conodont machine – Branson and Mehl, Stauffer, Cooper, and Huddle – acquired a head of steam and was moving forward at a tremendous pace. Had Schmidt published in English in the United States, would it really have stopped this machine in its practical tracks?

  On this possibility we can do rather more than speculate, for when Schmidt published his finds, twenty-eight-year-old Harold Scott of the University of Montana's School of Mines in Butte was making a similar discovery.16 The remarkable coincidence of these events has fascinated conodont workers, but Schmidt and Scott were not the only workers finding these “natural assemblages” at this time. As we have seen already, the conodont fossils only came to light when people started studying fossils with microscopes. By the early 1930s, micropaleontology was the new fashion and an increasing number of graduates were engaged in looking at rock surfaces in search of tiny fossils. In a few years most would turn to those mass processing techniques Branson and Mehl so favored, and in doing so lose any hope of understanding how the different conodonts are associated in the rock. But of all the microfossils being used in the new science, only conodonts were affected in this way by this change of practice. In the early 1930s, however, workers were not set in their ways and there were still doubts about the boiling and sieving of sediments. So, for a few years, there was a much higher probability that associations would be found: More people were looking and fewer were boiling samples.

  Scott was an Illinois man, born and educated in the state, and it was with that state's geological survey that he got his first geological summer job in 1927. He graduated two years later and got married on the same day. His career took him to Wisconsin and to oil consulting in Texas before the stock market crash forced him back to school. The Great Depression, rather ironically, turned out to be his big break. He won a fellowship at the University of Chicago and found himself in the fall of 1931 in what he considered one of the two greatest geological departments in the country. While there, the head of the Montana Geological Survey came calling, looking for a new staff member. Scott's supervisor, Carey Croneis, put him forward and he got the job. Scott realized how remarkably fortunate he was in this jobless country, but when he arrived in “bleak and dreary” Butte, he realized that his good fortune had come at a price.

  Scott wrote his recollections of these years late in life and in doing so appears to have conflated two summers of fieldwork. In the summer of 1933, he “collected some of the black shales and took them to the office.” In October of that year: “I decided to look at the shales under the microscope. To my astonishment, the first sample showed [an assemblage] of what are known as conodonts, complex teeth of an unknown animal. I immediately recognized their importance; they were the first [assemblages] ever found. I rushed to report upon them and have Elizabeth Lochrie draw them after my models.”17

  We shall come to this discovery shortly, but it is helpful to consider just how lucky Scott was at this time. It was probably in the summer of 1934, as he recalls, that this lucky streak continued. He had been asked to go out into the field to search for “pumpkin-seed gold” – whatever that was. He was given a car and an assistant but no salary, so he felt free to indulge his own interests a little too. He made several forays into the field that summer, but it was the last one that really turned his life around. On that occasion, he and his assistant entered the Big Snowy Mountains from the north, walked along the
top of “the big Madison Limestone,” and chanced upon some shales containing concretions. “They were unknown, unnamed and unmapped,” he wrote. “I broke open a concretion in the shale and oil ran out of the cavity. I was amazed because lying above the shales was a sandstone bed capable of holding oil. They all dipped eastward into the basins of eastern Montana and the Dakotas.” He rushed the discovery into print and almost immediately oil companies began to arrive in town. Scott later recalled, “The summer of 1934, without salary, had paid off. National attention on the oil potential of Montana and the Dakotas and international attention on conodont studies made the summer a land mark for me.” He rounded off this period of discovery by writing up the Montana earthquakes of 1935, again attracting much attention. This hat trick of discoveries put him in Who's Who and made him one of the most highly paid academics in Montana. They also bought him his escape, for in 1937 he was headhunted for the University of Illinois.

  It was in this context that Scott's associations of conodont fossils were found, and when he first looked at them he knew nothing of Schmidt's discoveries. Scott's fossils did, however, come from the Pennsylvanian (Upper Carboniferous) Quadrant Formation and were very broadly similar in age to Schmidt's. Scott had located seventy-five associations – or “assemblages” – of conodont fossils. This was eight times what Schmidt had found, but not one was as good as Schmidt's best (figure 3.2). Scott moved quickly to make his finds known and, being still in distant Montana, asked Croneis to present his preliminary findings at a meeting of the Paleontological Society in Chicago in 1933.

  He made his case more fully in a short paper published in December 1934 which he later said “attracted world-wide attention by workers in the field.” Here, Scott began by drawing upon a review of previous conodont studies recently published by Stauffer and Plummer. This enabled him to emphasize that dramatic seesawing of opinion that had fascinated commentators from the late nineteenth century onward. This little historical sketch aimed to do two things. First, it destabilized the existing fish; it demonstrated that the great and the good had never been able to agree on what the animal was and no new evidence had been presented to change matters, despite what some of his senior colleagues might think. Second, it acted like a Wagnerian prelude anticipating and reifying the significance of the drama that was about to unfold. With American opinion already firmly in favor of the fish, Scott knew he was about to introduce another sea change in thinking. He was sure the fish was simply an illusion and that he possessed the proof necessary to finally end its life. But just to make sure he was not making a grave error, he consulted Chicago professor A. S. Romer, author of the recently completed and groundbreaking Vertebrate Paleontology. Beyond their evocative – and yet puzzling – morphology, it was the fossils’ phosphate composition that most encouraged opinion to favor the vertebrate. But Romer told Scott that such evidence could not be relied up, and looking at the conodonts he concluded quite emphatically, “I cannot accept them as the remains of vertebrates.”18

  3.2. Scott's conodont assemblages showed repeated associations of fossils but lacked the explanatory power of Schmidt's finds. From H. W. Scott, Journal of Paleontology 8 (1934). SEPM (Society for Sedimentary Geology).

  In his paper, Scott presented his eighteen best, but still quite jumbled, specimens. Although conodont workers have claimed that Scott and Schmidt presented the same discovery, the quality of the evidence available to each man was remarkably different. While Schmidt's fossils were capable of making the argument for themselves, Scott's required a little more ingenuity if they were to have the desired impact. He did not possess a single specimen that gave a clear picture of the animal's apparatus, but he could reveal consistent associations of elements. Six specimens showed identical combinations. These, Scott believed, proved Ulrich and Bassler wrong; different elements did exist within the same animal. They did not represent separate species. The specimens that showed the best natural associations of parts, as judged by repeated symmetries, contained the long saw blade-like Hindeodella. These, Scott imagined, were probably grouped around the mouth orifice of the animal. That animal was, for Scott, most emphatically a worm. Scott ran through a series of numbered assertions, each of which he considered indisputable. Conodonts are paired and made up of right and left groups, thus not conforming to upper and lower jaws, a condition he felt essential for a vertebrate animal. The assemblages consist of no more than ten conodont fossils (Schmidt's reconstruction contained fourteen) – too small a number to be fish teeth. As many as four completely different types of conodont appeared in the same mouth. They lack a pulp cavity and appear to be attached to flesh in a manner incompatible with fish teeth. No other hard parts had been found, thus confirming the animal was soft-bodied. One can read in Scott's statements a predisposition to see a worm, but clearly he had written his paper after he had reached this conclusion. Thus, while he believed he gave an objective interpretation, this was undoubtedly an argument in favor of the worm: “It now seems impossible for conodonts to belong to any group of animals other than Vermes.”

  If the fish had been welcomed by those predisposed to such an animal, then we might wonder if Scott also looked at the conodont through similarly blinkered eyes. At a recent meeting of the Paleontological Society, Croneis and Scott had jointly presented a number of papers on fossil worms and even introduced the term “scolecodont,” meaning “worm tooth,” to cover a group of fossils they considered, like the conodont, of emergent paleontological and stratigraphic significance.19 The term “scolecodont” is still used today to refer to fossil worm jaws.

  Whether Scott's worm diagnosis affected the reception of his paper is unclear. He was certainly swimming against the tide. Some found his rather emphatic arguments convincing – one university lecturer even adopted the paper as a model of scientific argument with which to teach his students. But a fundamental corollary to Scott's discovery was that Ulrich, Bassler, Branson, and Mehl – indeed, everyone active in America at that time – was working on a false premise. Ulrich and Bassler's simple fishes were merely figments of their imaginations and certainly could not be used as justification for giving each type of conodont its own species name. Scott did not push the point. He was a practical paleontologist himself and valued fossils mainly for their utilitarian value. Also, as a young man, he simply could not afford to be outspoken, especially in a field where everyone knew everyone else, where jobs were scarce and enemies easily made. Scott had made his bold claim, but now he stepped back and recommended the continuation of current practices. Not really being a conodont worker, he soon returned to other things.

  Unknown to both Schmidt and Scott (and to most conodont workers since), at this same moment, the young Dan Jones was also finding conodont elements in natural association. In March 1935, Jones had just completed his master's dissertation at the University of Oklahoma. In it, he had made his own report on conodont assemblages from the Pennsylvanian Nowata Shale, which occurs in the north east of that state. Like Schmidt and Scott, he had begun his field and laboratory work in 1933, though he was still in his teens, and his discovery was also the result of mere chance. Having found Branson and Mehl's washing methods useless, Jones had resorted to splitting the shale by hand then using needles to expose the fossils. The assemblages he found were far better than those Scott possessed. They showed conodont fossils arranged symmetrically, just as one would expect if a bilaterally symmetrical body had been compressed. But Jones was still very young and had just been beaten into press by the high-flying Scott. Perhaps because of this he made relatively little of his finds. He did, however, listen to his departmental colleague, R. L. Denham, who suggested that the conodont elements might have been used for grasping onto a mate during copulation, as he had seen such things in living worms, including nematodes. Jones thought this a possibility. The idea entered the animal's mythology, encouraging Denham to publish his own ideas on the “elusive little animal” a decade later.20

  By the end of 1934, conodont studie
s had reached a new level of maturity. The conodont's place in stratigraphy was rapidly being established, a fish or worm affinity seemed very probable, and assemblages suggested biological complexity. Beyond those engaged in more thoughtful study, however, the enigma continued to attract armchair speculation. Thus within just two years of Scott's seemingly definitive and well-argued case, Frederic Loomis, a Massachusetts professor specializing in fossil mammals, muddied the waters by suggesting that conodonts might be the teeth of gastropods, thus reawakening an old idea which had been frequently dismissed. He felt sure conodonts would be found in deposits of much younger age “if sought.” It was a piece of recreational dabbling, but it underlines the sense in which the conodont was continuing to develop as an object of mythology – an Arthurian sword in the stone by which all comers might test their intellectual strength. As yet, conodonts could claim few people who specialized in their study, and so there was little notion of the insider and outsider in the debate. Conodonts were there to be claimed by any specialist wishing to include them in his group of animals. It was assumed that they would inevitably be found to belong to one established group or another. Few could have been surprised, then, when in 1937, Henry Pilsbry, an American expert in land snails in his mid-seventies, looked at these fossils and also saw mollusk teeth.21

  After years of economic and political turmoil in Germany, 1933 saw Hitler rise to become chancellor and the beginnings of anti-Semitism and book burning. Soon anti-German sentiments began to affect the reception of German science in the United States just as Schmidt's discovery was beginning to reach conodont workers there. In 1935, Stauffer was the first to record the arrival of Schmidt's innovations. He was convinced that the associations of conodont elements were valid and that “when good specimens or even good fragments of all these are found in close proximity, or as an assemblage of the remains of one individual, a long step towards the reconstruction of the animal can be made.” Branson and Mehl felt the “long step” had not been taken. They looked at Scott's assemblages and dismissed them as chance inclusions in “excretionary matter.” Their proof was that samples of isolated conodonts “fail to show proportional numbers of kinds supposedly found in one individual.” They added that the different types of conodont making up these assemblages had different stratigraphic ranges – how could these different kinds belong to a single animal? Their objections were to become fair tests of the theory. If refuted, then assemblages would be proved anatomical rather than mere coincidences. Until these doubts were answered, Branson and Mehl would continue to class conodonts as the remains of fish and deny the validity of assemblages. As evangelists for conodont stratigraphy their interests lay elsewhere and they were actively attracting new recruits to their way of thinking.22 As the most published and therefore the most authoritative workers in this field, their words had impact, particularly on those making practical use of microfossils. Increasingly, stratigraphers began to doubt the truth of Scott's claims.