Too Big to Walk: The New Science of Dinosaurs. Brian Ford J.
of God to this newly discovered land. The Navy organized the voyage on condition that FitzRoy meticulously surveyed the coast and the oceans around South America, so that precise navigational charts could be drawn up. Looking for new forms of life was nowhere in the plans.
The ship set sail on December 27, 1831. Darwin soon became absorbed by the many exotic life forms he encountered on that famous holiday. He was able to go ashore at will to collect and explore to his heart’s content. His adventures were comprehensively detailed in a book he wrote describing the voyage of the Beagle.14
He came to realize how coral atolls were formed, and he published a monograph entitled The Structure and Distribution of Coral Reefs. His adventures were many: in Chile he witnessed an earthquake. On the Galápagos Islands he dined on the flesh of the giant tortoises and later described how the different shapes of their shells seemed to match the lifestyle imposed by the environmental situation of the different islands. The Galápagos finches, he concluded, were similar to those on the mainland but had clearly changed over time. He noted: ‘Such facts undermine the stability of species.’ He then changed it by adding one cautionary word: ‘Such facts would undermine the stability of species.’ There was no implication here that the presumed changeability of species was a novel concept, just that his observations substantiated the accepted view.15
The accessible style and exotic nature of the subject brought a wide readership, and suddenly Darwin had a new career – as an author of popular science. To me, his most visible legacy is his list of published books, which represent a remarkable devotion to making science accessible. They are all vividly written. Apart from the Origin of Species, he wrote on the geology of South America and on volcanic islands (1844), on the fertilization of orchids (1862), the movements of climbing plants (1865), the effects of cultivation on variation in plants and animals (1868), the Descent of Man (1871), insectivorous plants (1875), the effects of cross-fertilization in plants (1876), The Different Forms of Flowers on Plants of the Same Species (1877), and finally The Formation of Vegetable Mould through the Action of Worms, with Observations on their Habits (1881). This last title was a best-seller. Remember, Darwin’s book on worms sold far more copies during his lifetime than the Origin of Species.
Curiously, Charles Darwin showed no interest in dinosaurs. He is the person who popularized the theory of evolution, in which dinosaurs would play such an important part, but he did not include them in any of his books. How curious that Robert Darwin, who had presented the first scientific account of a fossil reptile in 1719, had been Charles’ great-grandfather. Since Charles’ grandfather Erasmus had also written about evolution, it is surprising that although Charles Darwin himself was fascinated by fossils, he had nothing to say about dinosaurs. Although the fact is little discussed these days, Charles Darwin was an expert with the microscope and he became interested in the microscopical structure of fossilized plants. He knew that they had been faithfully preserved in rock, but how much could you discern with the microscope? Was the cellular structure preserved?16
Darwin was not the first to speculate thus. As long ago as May 27, 1663, Robert Hooke at the Royal Society of London had looked at fossilized wood under his microscope. As we have seen (here), Hooke had carefully scrutinized his specimen of fossilized wood, and had worked out how it was formed, and he ascertained that the fossil sample showed the same structure as a specimen of fresh wood:
I found, that the grain, colour, and shape of the Wood, was exactly like this petrify’d substance; and with a Microscope, I found, that all those Microscopical pores, which in sappy or firm and sound Wood are fill’d with the natural or innate juices of those Vegetables, in that they were all empty, like those of Vegetables charr’d …17
By 1665 Hooke had recognized that fossil wood was similar to the structure of present-day plants. Darwin made the same observation, but he took it a stage further. Rather than simply inspecting the surface, he resolved to have the rocky fossils ground down with an abrasive paste to produce the thinnest of sections – so fine that light could shine through to reveal the inner structure. He had collected fossilized wood during his sojourn on HMS Beagle in 1834 when they called at the Isla Grande de Chiloé, midway along the coast of Chile. He noted at the time that he had found numerous specimens of ‘black lignite and silicified and pyritous wood, often embedded close together.’ Joseph Dalton Hooker, the founder of geographical botany and the director of Kew Gardens for 20 years, was a close friend of Darwin’s and he catalogued the specimens for the British Geological Survey in 1846. The collections were then lost for 165 years, until Howard Falcon-Lang, of the Department of Earth Sciences at Royal Holloway College of the University of London, investigated some drawers in a cabinet labelled ‘unregistered fossil plants’ in the vaults of the British Geological Survey near Nottingham. Falcon-Lang reported: ‘Inside the drawers were hundreds of beautiful glass slides made by polishing fossil plants into thin translucent sheets, a process [that] allows them to be studied under the microscope. Almost the first slide I picked up was labelled C. Darwin Esq.’ This remarkable discovery was a treasure trove, and all the slides have now been digitized and put online for public scrutiny.
Stylised portrayals of an ichthyosaur and plesiosaur were published by Louis Figuier in La Terre avant le Déluge (the World before the Flood) in 1863. The drawing, by Édouard Riou, was engraved by Laurent Hotelin and Alexandre Hurel.
Given that the idea of evolution was fundamental to the understanding of dinosaurs in their temporal context, and that Darwin himself was an enthusiastic investigator of fossilized plants, it is surprising to me that he showed little interest in dinosaurs. Yet within two years of his book appearing, a discovery was made that seemed to provide the perfect example of evolutionary theory. This was the discovery in Germany of what seemed to be a creature halfway between reptile and bird – Archæopteryx. The skeletons and feathers have been excavated from the limestone quarries that surround Solnhofen, Germany. First to appear was a lone feather, found in 1860 by Christian Hermann von Meyer and now on display at the Humboldt Museum für Naturkunde in Berlin (see footnote here). Nobody can be certain it came from Archæopteryx, and it may belong to a similar (but different) genus, but the following year a skeleton was found in the same limestone at a quarry in Langenaltheim, 5 miles (8 km) west of Solnhofen. It was donated to a local physician, Karl Häberlein, in lieu of his professional fees. Knowing of the interest in palæontology then spreading across England, Häberlein sold it to the British Museum (Natural History) for the princely sum of £700 (today worth about £45,000 or $52,000). This has long been known as the London Specimen, and it is on display at the Natural History Museum to this day. The skeleton is mostly complete, though it lacks much of the skull and cervical vertebræ. In 1863 Richard Owen formally named it Archæopteryx macrura, admitting that it might not be the same species as the one from which the feather found by von Meyer had originated. Darwin was pleased by the find, for it fitted so well with the theories in his book. In the fourth edition, he added a note:
Now we know, on the authority of professor Owen, that a bird certainly lived during the deposition of the upper greensand; and still more recently, that strange bird, the Archæopteryx, with a long lizard-like tail, bearing a pair of feathers on each joint, and with its wings furnished with two free claws, has been discovered in the oolitic slates of Solnhofen. Hardly any recent discovery shows more forcibly than this how little we as yet know of the former inhabitants of the world.
It was many decades before further specimens of Archæopteryx were unearthed. The Eichstätt specimen was discovered in 1951 near Workerszell, Germany, and was not formally described until 1974, when details were published by Peter Wellnhofer. The fossil is on display at the Jura Museum in Eichstätt, Germany, and is of a curiously diminutive form. It has been suggested that it may be a different genus, and has been given the alternative name of Jurapteryx.