Clarkson sent the completed manuscript to Bengtson on June 21, 1982. They had kept to their timetable and finished it before the summer, but they had missed the October issue. It would be published in January, after a little tinkering with the finer details, and open the 1983 volume.3
In their description of the animal, the three men did not waste many words on all that had gone before; that was now simply irrelevant. Briggs had decided this early on, and Aldridge agreed. Melton and Scott's beast was unquestionably a conodont eater and Conway Morris's had nothing to do with conodonts at all. The new animal stood alone (figure 13.1). It was no surprise that it possessed no skeleton other than the conodont apparatus but a revelation to find that that apparatus was arranged back-to-front. From Schmidt onward, conodont workers had got this wrong. Only Jeppsson and Nicoll had dared to entertain this unorthodox thought. This put the long comb-like elements, two of which held a long, backward-pointing spine-like cusp, near the opening of the mouth. Behind these comb-like elements came the pair of stout blades, and behind these were the platform elements. Among the animal's most intriguing soft tissues was a pair of pale blue ellipses that formed dark lobes projecting toward the front of the body. Between them was a space perhaps leading to the mouth. The body of the animal also showed a line running down the center, evidence of segmentation, a tail fin, and a posterior fin.
In an instant dozens of speculative animals vanished from the minds of those who read the paper, but they were to be replaced by an animal that was frustratingly indefinite. What could it be? Briggs, Clarkson, and Aldridge narrowed the possibilities. There seemed to be just three. The eel-like shape, with possible lateral flattening toward the tail, the asymmetrical posterior and caudal fins, hints of a possible notochord, and indications of segmented muscles all suggested a chordate, but none of these features was so well preserved as to be definite. An alternative was the arrow worm or chaetognath as these animals have eyes positioned where the subcircular bodies appear in the conodont animal, and they possess a similar body shape. But chaetognaths do not have segmented muscles, and this new animal did not seem to possess the arrow worm's paired fins. Neither possibility was certain, and they decided to err on the side of caution. For now, the animal would remain in its own exclusive club, the Conodonta. It was still proving resistant. Indeed, it even proved difficult to give it a name. This relied on the identification of the platform elements, but these were poorly exposed. The authors resigned themselves to naming it Clydagnathus? cf. cavusformis, meaning it was probably or possibly Clydagnathus and like the species Clydagnathus cavusformis.
13.1. The conodont animal. This image closely resembles Clarkson's giant camera lucida drawing, 70 cm × 70 cm, of the “lamprey” he sent to Briggs. Clarkson already doubted that it really was a lamprey. The head is top right in (A), with conodont elements indicated in black and repeated structures indicated with stippling; (B) and (C) show the conodont assemblage preserved in the head region and preserved on facing rock surfaces. Reproduced with permission from E. G. Briggs, E. N. K. Clarkson, and R. J. Aldridge, Lethaia, 16 (1983).
Concealed within this name is a little poetry, for it was originally the invention of Rhodes, Austin, and Druce. Aldridge had been Austin's student just as Austin (and Druce) had been students of Frank Rhodes. It was Whittington who suggested to Rhodes that he study conodonts. Briggs and Conway Morris, who refereed the paper, had been students of Whittington. That it should be this animal and this name was pure chance, as were Aldridge's involvement and the role of Lagerstätten. But these coincidences are not evidence for scientific ley lines, merely indications of how small the palaeontological community was and how it was organized. One further linkage now developed in the form of Stephen Jay Gould, who had previously admitted that conodonts were rather alien to him, though like all paleontologists he was intrigued by what he called – borrowing from Churchill – this “riddle wrapped in a mystery inside an enigma.”4 Gould used the discovery of the animal as material for one of his regular articles on fossils in Natural History magazine. In it, and claiming Clarkson as a friend – Gould had visited Clarkson on a number of occasions and the two got on well – he used this fossil as a springboard to discuss his “Wonderful Life” view of evolution, documenting the exploits of Briggs, Conway Morris, and Whittington.
Briggs and his collaborators knew that on the most critical points the fossil was more suggestive than conclusive. More material was urgently needed, but a search of other Shrimp Bed collections turned up nothing. So Aldridge assembled a team that included his former research student, Paul Smith, and began a ground assault on the Scottish shoreline. With military force, they applied sledgehammers and crowbars to split the limestone until it would split no more. Acids etched the rock surfaces. But the animal was well and truly holed up. It did not appear. Adopting another line of attack, they tried to dissolve it out, submitting whole blocks of rock to acid immersion. Even this violent interrogation did not bring to light more than the occasional isolated element or cluster. The rock remained silent. There were no more animals.
All looked hopeless, but then things changed, and they did so remarkably. Inspired by a lecture on the animal by Clarkson, Neil Clark, an undergraduate at the University of Edinburgh, visited the site to look for himself. An inveterate fossil hunter with a nose for rarities, on this day – June 16, 1984 – accompanied by fellow collector John Hearty, he was to find the greatest of all rarities: the first in situ conodont animal and the second animal to be found. Hearty gave a “scoop” to MAPS, the newsletter of the Mid-America Paleontology Society. “As the sun beat down on us,” Hearty began, as he witnessed Clark find a host of unusual fossils. “Now, by this time you will have realized that Neil was having ‘one of those days’ – he could do nothing wrong!…but Neil wasn't quite finished.” It happened toward the end of the day, when his hammer blow laid open the animal. Unfortunately, this one lacked the conodont elements.5 “Just think of the consequences if this was the only other one found!” Clark later speculated, “No conodont elements in the head region of the animal – the original would have been reinterpreted as chance association.” Luckily it was not the only one. A short while later Hearty collected a block with another animal on it, which he only spotted when he got home. Clark later turned up another on a loose block. Only partially exposed, these animals were then passed to Aldridge and Briggs for further preparation.
At this time, the research site remained pretty much under the control of Clarkson and Briggs. Aldridge had been admitted onto their patch under certain conditions but also with the recognition that in some senses this research into the conodont animal would be a kind of inheritance for him since he was the only conodont specialist among them. As was the case for Melton and Scott when they believed that they held the animal, it was necessary to be sure that no one would enter the site and disrupt the research. Consequently, in April 1983, when Clarkson was contacted by a paleontologist whom Aldridge knew, and who desired samples of the Granton bed, Clarkson asked Aldridge for his opinion. Aldridge, who thought this worker completely trustworthy, told Clarkson that he could seek reassurance in “a covering letter asking him not to publish or publicize anything on the material without prior reference to you.” Clarkson had already begun to have a conversation with the Nature Conservancy Council, the government agency responsible for geological conservation, about protecting the site from inappropriate exploitation, vandalism, planning developments, and so on.
News of the discovery had reached Australia by September 1982. There, Robert Nicoll, who was studying Devonian clusters from the Canning Basin, asked Clarkson for an advance copy of the paper, adding, “If I can base some of this speculation on your animal it would be of great assistance.” In October, the Scottish Journal of Geology wanted a picture of the animal for its cover. In December, Aldridge wrote to Nature offering to write a news article on the animal and a “history of the speculation.” The journal's Alun Anderson responded, “I'm afraid we don't allow au
thors to write about their own work in News and Views.” Asking for a copy of the paper, he added, perhaps not as tersely as it seemed, “We will then decide whether to commission something on it from an expert in the field.” They decided to do so and a précis of the paper appeared in Nature two months later. New Scientist also carried an announcement at this time under the heading, “Museum piece solves palaeontology puzzle.” It ended: “The conodont animal has been found, but we still don't know what it is.” Those publishing the McGraw-Hill 1985 Yearbook of Science and Technology wanted the story and illustrations in May 1983. Soon cards were arriving from all over the world requesting reprints of the paper. Aldridge had, beforehand, compiled a list of 205 names of individuals known to him who were to be sent the paper. When Sam Ellison received his, he admitted to Aldridge to “being skeptic on many conodont problems.” It seems he remained doubtful about the new animal too.
Aldridge was not alone among the authors of the paper to also do the rounds, giving talks on the discovery of the animal. These were invariably compiled under titles like “The long tail of the conodont animal” but tended to spend little time on the enigma. As the research developed, so these talks changed, always incorporating the latest discoveries. However, there appears to have been no media frenzy; at this the team was to get much better. When, in July 1983, Aldridge read the headline “Dinosaur ‘find of the century’” in the British broadsheet newspaper the Guardian, he took the opportunity to write to the editor to point out an equally newsworthy story that had been missed. Briggs was having some success and had been asked to write up the animal for the Field Museum of Natural History Bulletin – Briggs was visiting scientist at this Chicago museum – and contribute to a new book on Problematic Fossils, asking Aldridge to collaborate on the latter. The animal also made its way into the world's popular scientific literature, but it did so slowly. In 1984, Géochronique published a short article titled “Solution d'une énigme: l'animal-conodonte.”
While the authors of the first paper searched for the future in real objects, others began to re-examine earlier debates in the light of the evidence of the Scottish animal. Among these was Stefan Bengtson, who was encouraged by Briggs, Clarkson, and Aldridge's tentative belief that the conodont elements were teeth. He revisited his model and dealt with the reversed apparatus and the animal's slender and mobile body. He now saw the animal as an active “macrophagous predator” (eating prey of relatively large size) in which the elements (teeth) sequentially grasped, held, directed, cut, and crushed.6 The tentacle-covered sieve favored by some of his rivals looked, by comparison, unworkable. No filtering system would put the fine filter first, he said, but then he admitted that the asymmetry of the animal's apparatus was problematic for all existing models. His solution was to remind his readers that the conodont elements were withdrawn into nonfunctional positions in pockets. Perhaps the apparatus only took on symmetrical form when extended and in use? This kind of “dilating pharynx” was seen in other animals that swallow large prey, such as the chaetognath, so why not the conodont? This functional connection to the chaetognath also enabled Bengtson to reaffirm his view that both conodonts and chaetognaths evolved from the same stock, the chaetognath-like protoconodonts.
This view seemed further strengthened when an almost complete Panderodus apparatus turned up in the Ukraine. Possessing simple conical elements, it was strikingly similar to the apparatus of the chaetognath, even if the two animals were very different in size. But Polish and Ukrainian collaborators Jerzy Dzik and Daniel Drygant argued that any similarity was mere illusion. It was simply that the distinctive ancestors of the two animals – Panderodus and the chaetognath – had evolved to become more alike. Dzik and Drygant further weakened Bengtson's position by arguing that the fossil's hooked simplicity meant that it must have functioned rather differently from the complex conodont apparatus seen in the Scottish animal. This then broke the connection between chaetognath-like protoconodonts and that animal. There was no longer any reason to believe that the one was ancestral to the other, they argued.7
Sweet also felt the protoconodonts an irrelevance. He thought they were more likely Szaniawski's chaetognaths than conodont ancestors. He preferred to see the conodonts as a unique group that emerged from that great evolutionary experiment recorded in the Burgess Shale: “More than a century of trying to make conodonts something else has done little more than emphasize their uniqueness…. So a reasonable reply to the query ‘What are conodonts?’ ought to be ‘They are conodonts,’ oughtn't it?”8 He had told Abe Zaidan, a reporter from the Akron Beacon-Journal who had probed Sweet about his work a quarter of a century earlier, “They were neither fish nor fowl, but conodonts.” Zaidan, who thought this unhelpful, translated the arcane “conodont” into “those fascinating little whatzits.” Sweet was amused but also doubtless a little frustrated that the news media could not handle the animal's name. Now he was annoyed that science could not deal with it either, for Briggs and his colleagues had called their paper “The conodont animal.” This had become necessary because science had, in the absence of the animal, slipped into the bad habit of calling the tooth-like fossils conodonts. Sweet reminded the authors that these animals already possessed a name, the one Pander had given them: “The conodonts.”9
Those outside the conodont community were rather less inclined to give the conodonts the degree of independence that comes with having phylum status. Briggs and his co-workers certainly preferred to find the animal a home in known biology, as did leading French fish paleontologist, Philippe Janvier, who would soon become one of the British team's principal antagonists. With playful mischievousness, he would soon force Briggs and his colleagues “to try harder.”10 Before the animal's discovery, Janvier believed conodonts were perhaps closest to vertebrates, a conclusion he reached from reading Gross. He thought the new animal's chevron muscle blocks and fins resembled those of chordates and suggested that the Granton animal might even belong to that exclusive chordate group known as craniates – animals with a skull. It was an idea others would adopt, re-awakening a possible relationship with jawed vertebrates,11 but this was further than Janvier was willing to go, and even Aldridge and Briggs thought the proposition unlikely. If the conodont animal did indeed belong in this chordate world, they thought it most likely to join the jawless fishes (the Agnatha).
Already these conversations were making assumptions about the animal possessing teeth, but Robert Nicoll, who had predicted the reversed apparatus in his filtering model, now returned to that topic to elaborate. Based on fused clusters from the Devonian, Nicoll imagined the anterior bar-like elements arranged parallel to the body of the animal, set in a food groove with cusps and denticles pointing downward. They were covered in tissue, which permitted the elements to continue to grow while also supporting cilia, which captured food particles and passed them down a groove into the mouth where the other elements would gently squash or shear through the soft food. “We now have a picture of the conodont animal as one who consumed particulate matter by swimming through the water with its mouth open,” Nicoll wrote. “It was…free to go where there was appropriate food, which may have been near the surface or at some depth. It is unlikely that the animal was exclusively a bottom feeder or that it burrowed in the sediment.”12 Far from being damaged by the new fossil, Nicoll's model seemed stronger than ever. Indeed, the vagueness with which many of the Scottish animal's features were known permitted conodont workers to continue to entertain diverse views. The animal's discovery had simply reinvigorated recent debate.
By now, a tiny heap of animals was accumulating in Edinburgh and Nottingham. There they remained largely out of sight. But then it was discovered that someone was interfering with their supply lines. The shift from mythological creature to a reality had placed the conodont animal on the fossil collectors’ shopping list. There could be few finds more prized, and there was an increased risk that commercial collectors with an interest in profit rather than science might pillage the site
in search of treasures to sell on the open market. Then, on one of his regular visits, on July 16, 1984, Clark was shocked to discover that someone had visited the site and taken away several square meters of the precious bed, leaving other rare fossils exposed to the elements. Clark told Briggs and Clarkson, who then contacted the Nature Conservancy Council. The Conservancy mustered “a lorry and a gang of tough fellows” to help remove much of what remained and take it to the Royal Museum's store at Newbattle near Dalkeith. This was on February 25 and 26, 1985. However, it was not this material, nor that previously found by Clark and Hearty, that led to the next development.
A new animal now entered stage left. No one saw it coming – not even those who had found it. It came from the Lower Silurian Brandon Bridge Dolomite in Waukesha County, near Milwaukee in Wisconsin – a rare Lagerstätte much older than that at Granton. Two amateur paleontologists, Gerald (Jerry) Gunderson and Ron Meyer, had collected it but not recognized what it was. Nor indeed had Don Mikulic and Joanne Kluessendorf, the two Illinois geologists working on the fauna. It was Briggs, his eyes now attuned to the animal's peculiar form, who spotted it in University of Wisconsin collections. Having announced the discovery with Mikulic and Kluessendorf, he was then permitted to choose his own collaborators in order to describe it. Unsurprisingly, he chose Smith and Aldridge. It had to be admitted, however, that alongside so many other wonderfully preserved fossils, this new animal was rather disappointing. Its Panderodus apparatus, consisting of simple cones and forming the only evidence that this was a conodont animal, was slightly detached from the remains of the soft tissues. One had to believe they belonged together. The animal did, nevertheless, preserve hints of segmentation, and this suggested that this conodont animal was not a chaetognath.13
The Great Fossil Enigma Page 35