Ulrich was not the only one yanked into action by Newberry's controversial claim. In 1877, Professor Albert Gallatin Wetherby, a mollusk expert and Cincinnati Society member, sent George Bird Grinnell at the Peabody Museum of Natural History at Yale a large number of varied specimens for identification. This museum had been established in 1866 from a $150,000 gift made by George Peabody, uncle of Othniel C. Marsh, who became Yale's (and the United States’) first professor of paleontology in the same year. Grinnell had been a student member of Marsh's first Scientific Expedition of 1870, undertaken in the company of William F. “Buffalo Bill” Cody, which with a military escort made some remarkable fossil discoveries. Marsh, who became wealthy as a result of his uncle's generosity, built extraordinary fossil collections and famously became an antagonist in the “Bone Wars,” which surrounded the discovery and naming of the American dinosaurs. Grinnell became one of Marsh's collectors and had also joined George Armstrong Custer's military expedition in 1874, which confirmed the discovery of gold in the Black Hill's of Dakota and then set off a gold rush. As white settlers encroached upon the Indians’ sacred lands, the Sioux and Cheyenne left their reservations. In June 1876, Custer and the Seventh U.S. Cavalry entered South Dakota in the hopes of controlling the “Indian problem” only to meet with their own annihilation at Little Bighorn. Fortunately, Grinnell had declined to accompany Custer on that fateful trip and instead found himself alive and well, and examining Wetherby's tiny fossils. Aware of their similarity to conodonts, Grinnell asked Marsh to obtain examples of these problematic fossils from Pander himself. These confirmed that Wetherby's fossils were not conodonts. They differed in color, structure, and chemistry. The Cincinnati fossils were, Grinnell concluded, the chitinous hooks of annelids (worms). Showing close affinity to the living worm Nereis, he gave these new fossils the name Nereidavus.24
For Grinnell, this was an unremarkable discovery – fossil worm trails had long been known; he had simply found evidence of the worms themselves. By implication, this meant conodonts could not be worms, or at least not the ancestors of modern forms as these were now known to be little different from those still living. Grinnell was emphatic about the distinctions. But by then Grinnell's focus was already beginning to change. The 1874 expedition had given him a great interest in local Indian tribes, and he would soon become an anthropologist and in time a fervent campaigner for the protection of the American wilderness.
Ulrich, who in 1878 had just obtained his first paid job in paleontology as curator at the Cincinnati Society of Natural History, thought the conodont question unresolved but favored the views of Owen and Morse. Paradoxically, having acquired specimens of several species of the modern Nereis from Wetherby for comparison, Ulrich took Grinnell's conclusions to mean that conodonts might indeed be worms. Ulrich was delighted to find “a striking resemblance between their jaws or hooks, and the little Conodonts that are so common in our rocks.”25 However, the young Ulrich hesitated, aware that the greatest authorities had not been so certain and that the fossils “present so little from which accurate conclusions can be drawn, and for that reason all the theories that have been advanced to solve the enigma are based on some points, of which they give a possible, and in some cases altogether probable explanation.” Without wishing to further mull over the different theories, he fell upon the annelid as the most probable answer to the puzzle and then speculated upon an ocean that “at times swarmed with innumerable worms” that left the slightest traces but “which the palaeontological collector has as yet not unearthed, but some of which he will undoubtedly bring to light in the future.” Ulrich would claim, nearly fifty years later, that he had been mistaken. It seems that he had not seen any real conodonts at this time and had been looking at worm jaws. Of course, no one knew this and so Ulrich's name was added to the list of those who had expressed yet another opinion on the identity of the animal.
By the mid 1870s, then, Pander's fish still had little support, despite Newberry's attempted resurrection. Newberry may have been the senior investigator, but behind Ulrich's conclusions stood Owen's tentative yet authoritative opinion, which continued to hold sway. But now perhaps the most astute mind to engage with the problem during this initial North American phase entered the field. It belonged not to one of those elevated authorities who seemed so versed in thinking within their own boxes, but to George Jennings Hinde, an amateur British geologist then in his early thirties, the son of a paramatta manufacturer who had taken up farming and had acquired a taste for geology around the age of sixteen, inspired by the writings of that popular Scottish literary “Robinson Crusoe,” Hugh Miller. Perhaps he had been motivated to pick up Miller on reading the eulogies that followed the sensation of Miller's death – he shot himself. A captivating writer, Miller had famously found extraordinary fossil fishes in the Devonian Old Red Sandstone: “Creatures whose very type is lost, – fantastic and uncouth, and which puzzle the naturalist to assign them even their class; – boat-like animals, furnished with oars and a rudder; – fish plated over, like the tortoise, above and below, with a strong armor of bone, and furnished with but one solitary rudder-like fin; – other fish, less equivocal in their form, but with the membranes of their fins thickly covered with scales; – creatures bristling over with thorns; others glistening in an enameled coat, as if beautifully japanned…. All the forms testify to a remote antiquity, – of a period whose ‘fashions have passed away.’”26 Miller's discovery of these fish in the 1830s was so well known that it was certain to have affected Pander's outlook, permitting him to think beyond known forms and see the conodonts as fish.
Hinde also attended the lectures of cave explorer and peripatetic popularizer William Pengelly, which he gave in Norwich in 1862. A man of solitary habits and a “silent and retiring disposition,” Hinde arrived in North America to study geology under Professor Henry Nicholson at the University of Toronto – which he did for seven years. He traveled widely, and as he traveled, so his interests moved to the “well-nigh invisible contents of the rocks”; “where other paleontologists went into the field armed with hammer and chisel…he took with him only a magnifying lens.” While at Toronto, Hinde published his first papers on a diverse range of geological topics, many of which reflected Nicholson's own interests. Nicholson, who had arrived in Toronto in 1871, had been asked by the government of Ontario to investigate the province's Silurian and Devonian fossils. Newberry also had invited him to describe Ohio's fossil corals and bryozoans for the volumes he was producing.
Hinde might have read of the debate then taking place in Cincinnati, because he decided to take up the cause of the conodont. Traveling and collecting around the Great Lakes, he knew the fossils themselves might not resolve the matter but that their associations with other fossils, and their distribution in time and space, might help formulate a more informed interpretation. On his return to Britain, Hinde also benefited from information from two contemporary British workers: Moore, who could now extend the conodont's range up to the Permian, and the Scottish fossil collector and local geologist John Smith. Smith, who was manager of the Eglington Ironworks on the Ayrshire coast of Scotland, had found conodonts in the Carboniferous in 1876, extracting them from the rotten limestone in a fashion that must have owed much to Moore: “Having collected a number of specimens, I sent them to this Society [the Natural History Society of Glasgow] for exhibition, and, if possible, to procure some information about them. As no one seemed to know what they were, I left them in the Hunterian Museum that they might be shown to visitors. The first caller who knew anything of them was Dr Hinde, who, on their being shown to him by Dr Young, at once pronounced them to be Conodonts.”27 Completely freed from the rock matrix, Hinde recognized that these conodonts were far superior to those he himself had collected in America.
Hinde's identification of the first Scottish conodonts prompted the society's vice president, John Young, to reflect on the animal's growing mythology: “Although these curious tooth-like organisms have now been kno
wn to Palaeontologists for more than twenty years, great doubts still exist as to what group of animals they belong.” Smith would later find conodonts from many English localities and even noted, rather prophetically but without effect, “They are found chiefly in the powder of rotted limestone, and, but rarely, in shale.”28
Hinde reported the results of his Great Lakes investigations in two papers read to the Geological Society of London in March 1879. His search revealed that between their earliest occurrence and the Lower Carboniferous, the conodonts had no regular association with other fossils, and thus the tooth-like fossils really were the only surviving parts of the mysterious animal.29 He had found conodont species very similar to those described by Pander that provided the first indication that these new and tiny things were distributed over immense distances and might, as a result, be used to correlate rocks. In contrast to Charles Moore, who had been overwhelmed by their eccentric wonder, Hinde could show that simple teeth, which Pander had found in such profusion, were restricted to the older rocks while the compound forms, composed of multiple points or cusps, had a far more extensive range. The Ordovician (as we now know it) and Middle and Upper Devonian were rich in these fossils. By contrast, in the intervening Silurian and Lower Devonian he could find none.
He had found that particular strata had particular conodont distributions. One layer, less than three inches thick, exposed at Eighteenmile Creek near North Evans on the southern shore of Lake Erie, was so crammed full of these fossils that he named it the “Conodont-bed.” This rock belonged to the Middle Devonian, and in this and the overlying Upper Devonian he found the variety of forms unparalleled. And then, at North Evans in the Upper Devonian Genesee Shale, in one lucky hit he split open a slab to reveal a cluster of twenty-four conodont fossils and associated “plates,” all squashed into an area no larger than a quarter of an inch in diameter. Hinde could not believe these fossils had been swept together by water currents, as the fossils themselves were too delicate and would have been destroyed. An alternative explanation was to believe that they represented a natural association, reflecting their presence in the soft tissues of the animal. They had simply been “crushed together into a shapeless mass” during fossilization. His conclusion was striking, for it suggested that different kinds of the conodont teeth occurred within the same mouth. He called the animal that possessed them Polygnathus dubius, a name which signaled not doubts about the truth of the association but rather its zoological meaning, as the new find did nothing to resolve the affinity of the animal or the zoological structure and function of the animal's jaw apparatus. It was a revolutionary interpretation that Hinde saw as a step closer to the truth. Unfortunately, the rest of his specimens were isolated finds and he had no way of artificially constructing associations between them. This meant that each of these fossils – if they were unlike those making up Polygnathus dubius – had to be given a species name of its own. In other words, for these fossils, he was forced to continue that practice Pander had reluctantly adopted. Like Pander, Hinde knew that twenty of his species names had no biological meaning; he reckoned that in all he possessed only two or three true species. In time he thought these true species would be recognized, but for the moment he had to accept a mixed system that, while it sought to establish a biological truth, sacrificed clarity and simplicity. This sacrifice was small, however, if all one wanted to do was understand the animal.
Huxley told Hinde that his Polygnathus dubius closely resembled the teeth of the hagfish such “that it would be difficult to prove that they did not belong to fishes of this order.” But he added that no living fish held such an assemblage. Hinde had found annelid worm jaws in the same strata as those in which he had found his conodont fossils. Like Grinnell before him, he could show that the worm jaws were distinct and possessed the morphology and chemistry of modern forms (figure 1.1).30 Hinde was emphatic: The animal that possessed the conodont fossils was not a worm. All the evidence pointed to conodonts being relatives of the hagfish as Pander had proposed, and he told his audience not to prejudge the past diversity of these fish on the basis of the “pauperized descendents of the present day.” While Hinde admitted that his evidence permitted only tentative conclusions, in two complementary papers, he had masterfully broken the thread of thinking that linked Owen to Ulrich. Now the dissidents – Pander and Newberry – appeared prophetic. The worm was dead, the fish resurrected. And in a few years, as American geologists began to investigate the same rocks and localities, so Hinde's ideas began to be consolidated. For the first time a complex biological species of animal – Polygnathus dubius – began to inhabit the American scientific mind.31
1.1. Hinde's proof. Hinde claimed that these different kinds of conodont fossil (left) came from a single animal, which he called Polygnathus dubius. He showed that these were in every way different from worm jaws (right). From G. J. Hinde, Quarterly Journal of the Geological Society 35 (1879).
While the French, British, and Americans had each in turn gotten a little excited, even perturbed, by the arrival of the conodont, the Germans had remained surprisingly quiet on a subject that had first been published in their language. It was the evangelizing Darwinian Friedrich Rolle who first broke this silence. Reviewing opinion, he concluded that if conodonts were not relatives of the hagfish, they might be related to the small eel-like amphioxus (or lancelet)32 or to the sea-squirts (which have remarkable free swimming larvae). Both these latter animals possess a notochord, a structure in place of the spine, seen in the embryos of vertebrates. It suggested that these invertebrate animals were related to vertebrates and that they might be brought together with the vertebrates in a group known as the chordates. It was a suggestion with connections to the pioneering embryological work of Baer and Pander and seemed to place the conodont in the realm of those animals from which vertebrate life first evolved.
German-speaking scientists could now no longer ignore the conodont. For Germany's Owen-like encyclopedist, Karl von Zittel, who had risen to fame during the 1870s, the conodont became a problem requiring resolution. Zittel was now working on his five-volume Handbuch der Palaeontologie, which was to become the definitive late-nineteenth-century guide to the study of fossils. Zittel's interest in the conodont may have arisen from the necessities of the book or have been triggered by the arrival of Hinde in Munich. Hinde had traveled there to begin a doctoral dissertation on fossil sponges under Zittel – an expert in the group – not long after his conodont paper had been read in London. To tackle this new conodont problem, Zittel teamed up with established Baltic fish zoologist Josef Victor Rohon, who over the previous decade had very usefully published on the anatomy of all those vertebrate and near-vertebrate animals considered to be relatives of the conodont: sharks and rays, lampreys and amphioxus. Rohon was also no stranger to the microscope.
From a review of the literature on the enigma, Zittel and Rohon noted that the conodont's “most faithful companion” was the annelid jaw. Perhaps this was important given that the conodont fossil itself was rather poor evidence for such anomalously early vertebrate life. Believing that they had the advantage of superior technologies and new knowledge resulting from recent discoveries in other fields, the two men felt a solution to the “conodont question” was in sight. What they lacked, however, were conodonts – a deficiency soon rectified with material from St. Petersburg and from Hinde's American collections.
Their investigation revealed the presence of organic material in the conodont fossils, which tacitly signaled a link to the chitinous teeth of worms. The sheer variety of form was to them even more conclusive: “Against an interpretation as the toothed jaws of vertebrates; it points rather to seizing, catching or supporting organs.” They could confirm the presence of interior structures described by Pander, but then denied most of them any significance. The lamellae survived their assault and they introduced fine radial canals, but the rest of Pander's carefully detected structures were now to be considered mere artifacts of fossilization. Their final
and most effective blow, however, relied upon the kind of visual argument Hinde had used to crush the worm, only here they were to destroy the fish. These pictures conclusively showed that the horny teeth of hagfish and their relatives “do not have anything in common with the conodonts.” With the fish destroyed, Pander's figures were compared with Ernst Ehler's published illustrations of bristle worms and with another kind of worm, the gephyrean, Halicryptus spinulosus.33 The similarity of external form was remarkable, and stripped of the materiality of the fossil and a history of interpretation that had long doubted that simple morphological comparisons were useful, Zittel and Rohon's argument was made complete. One did not need to be able to read German; one could simply look at these illustrations and believe.
The two men were in no doubt that these animals were worms of some kind and that “from the large diversification of form it can be concluded that the Conodonts represent numerous kinds and that thus in the Palaeozoic age the coasts of the seas were populated by a substantial number of the most different worms.” Only a few years earlier, Newberry had imagined something similar, only for him the seas were filled with small fish. Now that fish was dead, its lifeblood apparently an illusion brought on by erroneous interpretations. However, a more open-minded reader might have seen in Zittel and Rohon's arguments a conspiracy to murder an unsettling – if tiny – monster.
The Great Fossil Enigma Page 5
