The Great Fossil Enigma (25 page)

7.2.
Müller's oddities. Müller regarded most of his late additions to the
Treatise
, such as these fossils, as fully fledged conodonts. Among them was the extraordinary
Westergaardodina
with its ball. When a revised
Treatise
was published in 1981, nearly all of Müller's oddities were moved into the paraconodonts. This latter group had been redrawn to accommodate them: Rather than being that ragbag of conodont-like fossils Müller had imagined, it was now regarded as a special group of conodonts with large, deep basal cavities, no white matter, and a distinctive pattern of growth. Reproduced with permission from K. J. Müller,
Treatise on Invertebrate Paleontology
, Part W Miscellanea (1962). Courtesy of and ©1962, The Geological Society of America and The University of Kansas, and K. J. Müller,
Zeitschrift der Deutschen Gesellschaft für Geowissenschaften
111 (1959). Courtesy of
www.schweizerbart.de
.

Müller continued to collect Cambrian conodonts and, by 1959, possessed about twenty-eight hundred specimens, mainly from Sweden and northern Germany. These included many species he had seen in the United States. While this extended the possibilities for the conodonts in stratigraphic studies, these discoveries were also accompanied by a sense that conodont science was taking a bizarre turn. Some thought Müller's extraordinary fossils seemed to test the very boundaries of what might reasonably be considered a conodont. Now that there was no animal in mind – the fish and the worm, along with a menagerie of other possibilities, having been consigned to the dustbin by Gross and Wilbert Hass – how could one decide which fossilized things once belonged to this ambiguous and plastic animal? Even so, some may have doubted Müller's sanity when he included
Westergaardodina
among these fossils. A strange horseshoe-shaped fossil, first discovered in 1953, which came with its own detached “ball,” it looked nothing like a conodont. Other forms of this fossil were W-shaped. Indeed, they looked like nothing else known. But Müller found some primitive examples of these fossils possessing a distinctive tooth-like cusp, and along with their phosphatic composition this suggested to him that they belonged to an animal that had evolved from conodont stock (
figure 7.2
).
²²

While paleontologists outside the field celebrated Müller's perceptive association of horseshoe with ball, others doubted his powers of interpretation.
²³
Hass, for example, had examined “conodontlike objects” from Müller's beds in Utah and Wyoming back in 1954. Unable to see the laminations typical of conodonts, which he knew might have been destroyed by formic acid preparation, he concluded in the
Treatise
, “It is the writer's opinion that the stratigraphic range of conodonts should not be recorded as definitely extending into the Cambrian until irrefutable, well-documented evidence has been published.” Hass's opposition, however, faded with his untimely death. And being one of those tasked with finishing Hass's
Treatise
, Müller chose not to edit Hass's words but to contradict them in a supplementary section in which he described and illustrated his new and controversial Cambrian fossils.

Some of these new fossils were more debatable than others. The paraconodonts, for example, seemed to grow by additions to the lower rim. It remained an open question as to whether they were really conodonts; Müller made no presumption either way. Nevertheless, they sat there in the company of conodonts, carrying a suggestive name and implicitly pushing at the boundary of what a conodont might be.

It was a provocative move that soon met with criticism and disbelief. There were those who wished to return some of these objects and the concept of the conodont to their former meanings. Sweet and Bergström were the first to act, rescuing the useful
Pygodus
from the paraconodonts and placing it among the “true conodonts.” Maurits Lindström was willing to accept the cone-shaped forms Müller had found in 1956, not least because he had direct information from Cambrian expert “Pete” Palmer of the U.S. Geological Survey in Washington that these really were conodonts. By 1964, Palmer possessed a sequence of conodonts from Wyoming that showed their development from a simple horn-shaped form to a primitive
Cordylodus
and then on to
Cordylodus
proper in the lowermost Ordovician. It had been Palmer who had advised Müller on the Oklahoma rocks and supplied him with material from Wyoming and Utah. Lindström was, however, rather less impressed by Müller's more exotic European faunas, dismissing
Westergaardodina
as “highly interesting and valuable” but “not conodonts, at least not strictly speaking.” He doubted that others of Müller's fossils were truly Cambrian.
²⁴

Müller was rather annoyed at Lindström's dismissal of his work, based as it was on mere opinion. He remained silent until the Pander Society's first major symposium in 1969. By then the Cambrian conodont was beyond dispute. Each year had added a new site. Cambrian conodonts were now known from as far away as Iran, China, and Australia. They remained, however, rare objects in the Upper and Middle Cambrian, and one doubtful report even suggested they might be found in the Lower Cambrian.
²⁵

As Müller almost singlehandedly began the process of giving the family tree its root system, so a rather different argument was taking place in the upper branches. Here Walter Youngquist, a postwar product of the Iowa school who for a short time became the most active worker in conodont stratigraphy, claimed to have discovered conodonts in the matrix of some Triassic cephalopods from Idaho in 1949. He was pretty sure these were Triassic fossils, but he recalled Branson and Mehl's response to an earlier German discovery of Triassic conodonts. In 1941, it had been logical for these two men to consider such fossils as mere contamination, reworked into these younger rocks following the erosion of Permian or other strata. But then, in 1946, American D. B. Eicher of Standard Oil had reported finding Triassic conodonts in Egypt, which Branson and Mehl had also doubted. The wily Youngquist did not want the same fate to befall his finds, so he sent the same slide of specimens to Chalmer Cooper, Eicher, Ellison, Furnish, Hass, and Mehl, along with a list of pertinent questions: Are these conodonts? Have you seen specimens exactly like these in the Paleozoic? Given evolutionary trends, are these compatible with a Triassic age? Do they look like they have been reworked? With Branson out of the picture, both Ellison and Mehl thought these new fossils similar to the German ones Mehl had earlier dismissed. To a man, Youngquist's respondents thought that the fossils conformed to what one might expect Triassic conodonts to be like, and that none appeared to have been reworked. Cooper and Hass also told Youngquist that the National Museum possessed similar fossils, found just fifty miles away from Youngquist's find location. Any residual doubts these men possessed arose from their ignorance of the Permian fauna, but here Youngquist was a little ahead of the game; he had sufficient information to know his new fossils were different from those found in the Permian. Now he was sure that Triassic conodonts really did exist.
²⁶

With the conodonts considered rare but proven survivors of the great extinction at the end of the Permian, it was now possible to imagine the animal existing well beyond the Triassic – perhaps up to the next great extinction at the end of the Cretaceous. But Stauffer's reported discovery of conodonts in Cretaceous rocks in 1940 seemed to be a clear case of contamination and Marburg doctoral student and Triassic specialist Reinhold Huckreide's search for conodonts above the Triassic in the Alps in 1955 ended in failure. Indeed, his Triassic fossils showed such senile and variable characteristics that he was convinced he was seeing an animal on the verge of extinction. Then, in 1956, East Berlin's Kurt Diebel reported “authentic conodonts” from the Upper Cretaceous of Cameroon, West Africa. This led to Huckriede's suggestion that the animal must have been restricted to a particular sea, though he had his serious doubts about Diebel's fossils, which looked characteristically Triassic. He simply could not believe that they really were of Cretaceous age.
²⁷

Diebel's material had actually been collected in 1897–88, and consequently some now doubted its reliability. Hass called for a worldwide search.
²⁸
Others, however, welcomed the Cretaceous conodont. Lindström, who was working away at his conodont book, was convinced by Diebel's finds: “The fauna is too well preserved to have been derived from mechanical reworking through erosion of older, conodont-carrying sediments. Moreover, no such older sediments are available in the neighbourhood…. From its appearance the fauna can easily be accepted as Mesozoic and younger than the Triassic.” He thought it simply marvelous: “Through more than 300,000,000 years the same structural plan persisted essentially unaltered.” Each zero emphasized just how remarkable this unknown creature this was.
²⁹

Müller attended a micropaleontology conference in Nigeria in 1965 and spoke on Diebel's problematic fossils, but any hopes he might have had to resolve this matter in the field were dashed by “political circumstances.” Like Huckriede, Müller thought the conodonts must have had a restricted distribution at this time as they had not been found anywhere else despite a great deal of micropaleontological work on Jurassic and Cretaceous rocks. This encouraged the thought that the animal might still exist, swimming in a sea somewhere.
³⁰
After all, the Coelacanth had risen, Lazarus-like, from the dead as recently as 1938, and it too had been thought to have perished along with the dinosaurs in the Cretaceous. The impenetrable Congolese swamp held many mysteries, including the mythological Mokele-Mbembe. Might another mysterious creature still exist somewhere off the African coast?

Those reading and believing Lindström's textbook saw a “big, blank interval” standing between the Triassic and Cretaceous in which no conodonts had been found. Perhaps they thought that, with a little patience, this gap might also be filled. They did not have to wait long. In 1967, two Japanese workers reported conodonts from the Upper Jurassic.
³¹
Lindström's optimism seemed to have been rewarded, but in fact this turned out to be the last straw.

Unconvinced by the Japanese and African fossils, Triassic specialist Cameron Mosher led the assault against them. By 1969, he knew sufficient of the evolution of the Triassic conodonts to be able to demonstrate that post-Triassic examples simply did not exist. They were merely contamination. He could show that those from Cameroon were exactly like those found in the Middle, rather than Upper, Triassic. The Japanese fossils looked like those Huckriede had found in the Triassic, but the Japanese workers – convinced by the Cretaceous fossils – had imagined them as a missing link between the Cretaceous and Triassic forms. Now with the Cretaceous fossils in freefall, Mosher and Müller asked the geologists at Kyoto University to reinvestigate the site of the Jurassic finds. The results of that investigation proved inconclusive. This did not matter, however, for Mosher soon unraveled the final stages of conodont evolution in the Triassic. That period showed a rise in the number of highly specialized and rapidly evolving forms that could not have persisted as relics into these later periods.
³²
Such forms tended to exploit short-term niches. Ironically, then, the post-Triassic fossils were merely contamination. If anything, it made Branson and Mehl's initial doubting of Triassic forms all the more reasonable. Contamination really was a problem. Perhaps to no one's surprise, no further post-Triassic conodonts appeared, and the family tree was clipped back. The Cretaceous conodont, however, remained where it had been, printed on the pages of Lindström's book, encouraging dabblers and outsiders alike to imagine – well into the 1970s – that Cretaceous conodonts really did exist.

By 1970, the tree might not have been perfected, but who could doubt the strength of the evidence? Who could doubt paleontology's contribution to understanding evolution or, indeed, the importance of that knowledge to the correlation of rocks across time and space? Fluid and organic, continuous and gradual, the conodont evolved as Simpson and others had imagined in the 1950s, and Brinkmann before them. But this work had taken place without high-level evolutionary theorizing.
³³
Then, in 1972, paleontology was again shaken out of its lazy suppositions by Stephen Jay Gould and Niles Eldredge. Gould was to become the public face of American paleontology in the late twentieth century. His rise to public notice began now as he took on the role of the “bulldog of evolutionary biology,” later to be considered a “living legend” by U.S. Congress.
³⁴
Eldredge had been a fellow student with Gould at graduate school and had become a staff member of the American Museum of Natural History. Together they challenged the belief that species evolved gradually from large populations. They suggested that the gradualism the conodont workers and others had seen was merely a result of their own earlier conditioning.
³⁵
It had long been understood, they claimed, even by Darwin himself, that the fossil record is composed of species suddenly appearing, maintaining some constancy, and then disappearing. The formation of new species required the separation of a species into two or more discrete populations in which evolution could take place independently. In time – and virtually no time at all in geological terms – the populations would become so distinctive that they could not interbreed. Consequently, the fossil record would show the sudden appearance of species; it could not show gradual change. The branches of the tree did not sweep gracefully upward, they said, but appeared suddenly in midair, tentatively connected at right angles to each other. The species so formed continued unchanged. Eldredge and Gould called this their theory of “punctuated equilibria,” but their first assault met with considerable opposition, and the two withdrew to regroup, returning in 1977 to answer “all the hubbub.”
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