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14: Over the Mountains of the Moon
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325 325 Over the Mountains of the Moon In the mid-1980s, out of sight of those debating the meaning of the first Scottish animals, the next big step was being taken in a part of the world that had thus far proven itself completely lacking in these extraordinary fossils: South Africa. Here, along a dirt road in the Cedarberg Mountains, some two hundred kilometers north of CapeTown,GeologicalSurveyofficersDanieBarnardo,JanBredell,and Hannes Theron came across a new borrow pit for road metal exposing the soft and rarely seen Upper Ordovician Soom Shale.1 They stopped to investigate and found their curiosity rewarded with some intriguing fossils reminiscent of graptolites. Graptolites are one of those classic groups of extinct animals all paleontologists study at some point in their training. Tiny, colonial–bearing a passing resemblance to corals and bryozoans–their fossil remains are most common in shales, where they look like minute flattened saw blades. Theron sent a specimen to Barrie Rickards at Cambridge University in the UK, an expert on this group, to see if they really were graptolites. Rickards said they were not. A number of scientists at the Survey headquarters near Pretoria, including palaeobotanist Eva Kovács-Endrödy, however, became intrigued by the similarity of these new fossils to strange spiny plants found in much younger Devonian rocks. If this was what they were, then these were clearly important finds. In an echo of Pander’s conodont discovery, they would push back the origins of plants by forty million years. The oldest plants known at that time came from the late Silurian. Theron and Kovács-Endrödy prepared a paper naming these new plants Promissum pulchrum, meaning “beautiful promise.”2 They did not know fourteen 326 The Great Fossil Enigma that rather than being harbingers of a green and pleasant Eden, these new fossils held a beautiful promise of a rather different kind. Asisthenormalcoursewithscientificpublication,thepaperwassent out for independent external expert opinion. The task of reviewers is to considerapaper’smeritsandtoadvisetheeditorsonwhetheritshouldbe published. On this occasion, one reviewer believed the authors had not demonstrated that these fossils really were the remains of plants but left thedecisiononpublicationtotheeditor.Thepaperwasfinallypublished alongside a reply by the critical referee and a response from the authors. This discussion mentioned Rickards’s view that the fossils were not graptolites, but Rickards was concerned that he had been quoted when he had only seen one specimen. So more material was sent to him by diplomatic pouch and he confirmed his conclusion that they were not graptolites. He thought they looked rather jaw-like and discussed them with several of his colleagues. Together they alighted on the idea that these fossils just might be conodonts. The main problem with this identification was their size; they were more than ten times bigger than the conodonts they were used to seeing. Rather than being up to two millimeters long (though usually much smaller), these were up to two centimeters long! Rickards knew these fossils crossed the boundary of his expertise, so he contacted Dick Aldridge. Aldridge was intrigued and traveled to Cambridge the next day. It was to be another important day, for here he sawthefirstconodontspecimensknownfromAfricasouthoftheSahara and the first complete apparatuses from the Ordovician. And if these werenotinthemselvesmajormilestones,hecouldalsoconfirmthatthey belonged to a giant animal. Preserved merely as molds, Aldridge empathizedwiththeSurveyofficerswhohadstruggledtoidentifythem .They were, in every sense, conodonts like no others and totally unexpected. Seekingfurtherconfirmation,inAugust1987Therontooksomespecimens to the Devonian Symposium held in Calgary, where he showed themtoanumberdelegateswithexpertiseinfossilplantsandconodonts. They were overwhelming of the view that these fossils were conodonts, albeit of amazing size. Nevertheless, back in Pretoria, Kovács-Endrödy and others remained wedded to the plant and insisted that they continue with the publication of a more extended paper advancing this idea. [44.192.247.185] Project MUSE (2024-03-28 09:25 GMT) Over the Mountains of the Moon 327 Theron was, however, now convinced the fossils were conodonts and withdrewasacoauthor,laterjoiningRickardsandAldridgeinpublishing a paper identifying Promissum as a conodont. African conodonts, apparatuses, giants–there were many reasons for the South African geologists to welcome the news. They may have lost their landmark discovery of plants, but they had gained something quite extraordinary. Communication lines now opened between Aldridge and the Survey workers, and in 1990 he found himself traveling to South Africa to study their collections of Soom Shale fossils. At the time, all he knew was that there was a wonderful opportunity to progress science’s understanding of the animal in this part of the world. Ever since the...