Dry Storeroom No. 1 (12 page)

Another astonishingly spiny fossil trilobite from the Devonian of Morocco: the spines on this odontopleurid are genuine, but fakes are often offered for sale.

This example is typical of the kind of problems that exercise the judgement of a taxonomist, a mixture of scholarly research and careful observation. The history of naming animals and plants is full of examples where labels have been incorrectly applied. In the nineteenth century communication between scholars was imperfect, so it was then quite likely that an animal or plant might have been named twice by accident. The priority rule often had to be applied. I regret to say that there were also numerous cases where scientists “rushed to press” to establish their priority over any potential rivals. One of the most infamous examples concerning fossils was the race between Professors Edward Drinker Cope and Othniel Charles Marsh in the latter half of the nineteenth century to describe and name the spectacular North American dinosaurs then coming to light. This was a case of intellectual war, fought out in publications and in academic disputes. The two protagonists really loathed one another, and each was determined to name any newly discovered animal before his rival. Such enmity certainly stirred up a fever of activity in the prosecution of the war of reputations, but sometimes the casualties were names that got caught in the crossfire. In other examples, it is hard to establish who or what has priority, and the bemused scholar will find himself examining the small print on inside covers to find out whether a given book was published in May or September of 1799. I have used faded library stamps as evidence of the receipt of a publication by the Museum—which must therefore have been published earlier in its country of origin. What is evidently needed is a set of laws to sort out nomenclatural disputes—and so we have the International Code for Zoological Nomenclature, and there is a botanical equivalent. I have to admit that the Code makes for pretty dull reading and can, in the wrong hands, become a pedant’s playground. But it generally works to sort out which name is the valid one. However, there are cases when a rigid application of the Code would result in something silly happening to very familiar names. This might occur, for example, if some bookish scholar discovered a work of unprecedented obscurity containing earlier names for well-known animals. It would be highly undesirable in this case rigidly to apply the rule of priority, for names are a means of communication first and foremost, and nobody wants to revive an old name just for the sake of it. But how can a zoologist decide when to flout the rule of priority? The answer is to apply to the International Commission on Zoological Nomenclature (ICZN) with details of the case in question. With sufficiently good reasons a later name might well be conserved—this is decided by a vote of the Commissioners, who are an international group of taxonomists. Mostly this is just a way of formalizing common sense.

But it is necessary to have a court of appeal on names, because there are millions of species of animals still to describe, and it would be amazing if there were not more nomenclature conundrums thrown up, quite apart from having to continue to deal with problems arising from the last 250 years of scientifically naming animals.
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Lack of glamour was never a problem for
Archaeopteryx.
This is probably the single most famous fossil in the Palaeontology Department: “the first bird” is how it has been referred to for generations. Its full scientific name is
Archaeopteryx lithographica.
The species name refers to its occurrence in the Jurassic lithographic limestone mined around the towns of Solnhofen and Eichstatt in Germany. It is exposed in a very large open quarry where thin, flat slabs of nearly white limestone can be prised up from the outcrop as if they were stacks of tiles. As its name implies, this fine-grained stone is perfect for making lithographs. Occasionally, the quarry yields the laid-out skeleton of a fossil on a slab, as perfect as a picture at an exhibition. Most commonly these fossils are fish, but very, very rarely an
Archaeopteryx
will turn up. The eight specimens known so far represent the yield from millions of tonnes of rock. The rock was originally laid down in a lagoon, but one that was fatal to most animals because of its low oxygen content—which also protected potential fossils from destruction by scavengers. Fish that swam in from the open ocean were both doomed and immortalized. Where sticky lime banks rose above the water level creatures like
Archaeopteryx
might get trapped—there are also several species of flying reptiles, or pterosaurs, from the same deposit. The critical specimen at the Natural History Museum was discovered in 1861, and Richard Owen secured it for the then British Museum for £700. That was a very large sum of money for the time; it is misleading to make simple conversions, but consider that a house could be bought then for about a hundred pounds. Owen had realized quite quickly the importance of the new fossil, and gave it its name and first description in 1863. The type specimen, the holotype of Owen, is for ever BMNH 37001. The bantam-sized fossil is spread-eagled on its slab like roadkill, feathers splayed, a buff skeleton on a cream background. It is kept out of the way within the department in secure storage: the specimen on display in the bird gallery is a carefully made replica. I think we could probably scale up the value of the original today in proportion to Owen’s purchase price, so a measure of caution is prudent.

You must not get the idea that once the specimen has been labelled “holotype” and filed away in its appropriate box behind the scenes that means the end of its active life, apart from an occasional dusting. Nothing could be further from the truth. The specimen is available for reexamination and reinterpretation. No scientist ever has the last word, much as he might like to think he has. Historical reality is continuously remade, as ideas evolve and change. The geological past is a construction of the mind: study of specimens is worthwhile if it serves to push interpretation a little further in a new direction. No doubt when Owen described
Archaeopteryx
he thought he had made as much of it as he could, and he had certainly realized that it showed the combination of bird and reptilian features that has given it such an important place in the history of palaeontology. But as other specimens were discovered, further details were noticed. Refinements in preparation techniques allowed yet other features to be excavated; the late Peter Whybrow spent many hours using a mechanical pin under a microscope teasing out buried bits of bone on the type specimen. A dozen experts of their day have given the same specimen of
Archaeopteryx
a close inspection, and you might be forgiven for thinking that anything that could be extracted from it must have been by now. But the importance of the type specimen has been revived yet again in the last few years since the discovery in China of feathered dinosaurs. Feathers, it transpires, are not a uniquely avian characteristic after all. While this adds greatly to a theory that birds are descended from dinosaurs, it does open up the possibility that
Archaeopteryx
is not, after all, the first bird of common knowledge, but actually another slender dinosaur, a coelurosaur, which was on its way to becoming a “proper” bird. Or, which is the same question in different dress, what are the characteristics of a bird, if not feathers alone?

Modern anatomists recognize very well that there are a number of features that
Archaeopteryx
shares with relatively small and graceful coelurosaur dinosaurs; these are mostly primitive characters. While this may tell us about the ultimate line of descent of the Solnhofen flyer from some kind of diminutive inhabitant of Jurassic Park, what we are really looking for are advanced characters that
Archaeopteryx
shares with true birds, particularly if we wish to know whether birds +
Archaeopteryx
constitute a natural clade, such as I described in the last chapter. Teeth, for example, which
Archaeopteryx
has in abundance, are neither here nor there as far as its classification is concerned, because they are merely a feature retained from its dinosaur ancestor. Much more significant is the fact that the asymmetrical flight feathers on its wings and tail resemble those of modern birds, and they are not like the feathers of feathered dinosaurs. To use a hackneyed phrase, they are “fit for purpose” for flight. What was needed now was new information to clinch the matter, and that meant going back to the specimens yet again. Out came the slab bearing Owen’s holotype once more. This time, Angela Milner and her collaborators were trying out a new technique on the old specimen. They were looking into the braincase of the feathered fossil using X-ray CT (computed tomography) technology—well, if it can peer into the intimate spaces of human anatomy, it ought to work on an old bird. The results were beyond all expectation, and sufficiently startling to earn a place in
Nature
in 2004. The palaeontologists were able to model even fine details of the brain, demonstrating beyond question that the Jurassic animal had a highly developed visual system and expanded auditory and spatial sensory perception. They even managed to produce a model of the inner ear of
Archaeopteryx,
an object only a couple of centimetres long. All the evidence was consistent with
Archaeopteryx
as an animal capable of powered flight—not perhaps the equal of the aerodynamic marvels of the modern era, but nonetheless a fully effective flyer. If it looks like a bird and flies like a bird, then, by golly, it
is
a bird. Why, it even thinks like a bird!

So now the famous specimen is back in its drawer once again. Its records will have been updated with the latest details of scientific publication—all rather dry notes compared with the real excitement of the new discoveries. We know a little more about the intimate daily life of what was almost certainly a real bird. We also know that feathers had been acquired by dinosaurs before their avian descendants ever took to the air. Feathers are evidently another example from the fossil record of what Stephen Jay Gould called exaptation—a structure appearing for one purpose and then being recruited for another. Feathers may originally have been selected for insulation. It goes almost without saying that not every researcher will agree with what I have just said. There is still a small but vocal school that disputes the relationship between dinosaurs and modern birds. Science is all about disagreement. It is likely that the “BM
Archaeopteryx
” has not made its last public appearance. After all, nobody can anticipate what new techniques may yet be applied to the unfortunate bird that found itself trapped in calcareous mud in an ancient lagoon sweltering under a hot sun in what would, one day, become Germany.

The examples of
Erbenochile
and
Archaeopteryx
will demonstrate that discoveries officially become recognized only when they are published. This is true of science in general, and natural history provides no exception. Up until the point of publication a discovery is only provisional, and most scientists enjoy a certain measure of nervousness while a scientific paper is in that limbo known as “in press.” Some unscrupulous rascal might yet sneak into print ahead of you! Scientific names are the least of it. Nowadays, it is publish or perish,
Nature
red in tooth and claw, unnatural selection—and, to the winner, the spoils. The description of a scientist, no matter how brilliant, as a “non-producer” is a very effective way of blocking his or her promotion. The result is that too many papers are published, and many scientists are so busy keeping ahead of their rivals that they don’t even have time to read what other workers write.

Life as a scholar was not always so fraught. When Leslie Bairstow was appointed to the Department of Palaeontology in 1932, the Keeper of the day was reported as rushing through the offices crying excitedly:
“We’ve got Bairstow! We’ve got Bairstow!”
He came from Cambridge trailing glory after a brilliant undergraduate career, having been appointed to a Fellowship at King’s College at a prodigiously young age. He moved into a safely tenured position at the BM and proceeded until retirement to publish—nothing. Not that he was idle. He had started researching assiduously the strata of the Jurassic Lias Formation around Robin Hood’s Bay in Yorkshire. The shales and impure limestones of the Lias are beautifully exposed in cliffs and along the foreshore in the bay close to the charming old fishing town of Whitby. The commonest fossils from the Lias are probably the coiled molluscs known as ammonites, which are also used for dating its successive levels. Handsome, glossy specimens of the genus
Dactylioceras
are commonly sold in rock shops, and not just around Whitby. Local legend has it that they were originally snakes turned to stone by the Abbess of Whitby, St. Hilda, and some were even embellished with carved snakes’ heads to add authenticity to the story. By now it will be no surprise to learn that St. Hilda, too, has a genus named for her—
Hildoceras
(ammonites conventionally have the suffix
-oceras
). Bairstow devoted his attention to another group of fossils, belemnites, which can be collected throughout the Lias. They had been rather neglected, and perhaps this is not altogether surprising, because they are, frankly, rather dull-looking fossils. Their appearance is often compared to that of cigars, and indeed they do range in size and shape from small cheroots to generous Havanas. These common fossils are just the calcite “guards” of squid-like molluscs, and remains of the whole animal are hardly ever found. So the palaeontologist is working with scraps. Bairstow collected belemnites from layer upon layer of the Lias, and meticulously recorded their occurrence. This did not satisfy him, and so he had to return to collect on an ever finer scale, thus acquiring many more specimens, all of which needed curation and filing. He developed a reference system that operated with cards and knitting needles, a kind of Heath Robinson precursor of the punch-card filing system. His collections grew and grew. It is said that he filed everything. When he was sent specimens in parcels to identify, which he did with great thoroughness, he would unpick and save all the bits of string with which they had been trussed, and file them all according to length in special boxes. When he retired there were discovered a number of such boxes, labelled “string: 2–3 feet” and so on. One box was labelled “pieces of string too small to be of use.”