The megatherium in the National Museum of Natural Sciences in Madrid is quite unique in the world, because it is the first reconstruction of a large extinct vertebrate in any museum. The story of how it was exhumed, drawn, mounted and finally identified lies somewhere between forensic anatomy and guesswork, rather like a jigsaw without an illustration as a guide, or a Rubik’s cube without instructions. It was the time of the French Revolution. Palaeontology was taking its first steps. The history of life did not yet exist. That of the Earth was beginning to emerge, in all its vastness, the depth of time. The case soon awoke the interest of naturalists of both worlds, becoming an object of global knowledge, able to connect debates and arguments from Buenos Aires to Paris and from Madrid to London and Virginia.

The discovery took place in a ravine of the Luján River, a tributary of the Río de la Plata or River Plate. At the beginning of 1787 Manuel de Torres, a Dominican friar keen on natural history, unearthed some bones of what looked like a strange animal of great dimensions, a ‘wonder and providence of the Lord’, in his own words, a description echoing the tradition that linked monsters with divine plans. Aware of the value of the piece, the viceroy of Río de la Plata, the marquis of Loreto, ordered it removed to Buenos Aires. There it was drawn by a cartographer of Portuguese origin, José Custodio Sáa y Faria. First he drew the different separate bones, as in anatomy textbooks, showing the powerful spine, the head and two limbs, one foreleg and one rear leg, both very powerful. And then he ventured to recreate its form, a very risky exercise, since neither he nor anyone else knew what animal it was. The shape he gave it appeared equine, in a rigid posture, on its four legs. But the caption to this second drawing confirms the doubts: was it an amphibian or an aquatic animal? An elephant or a rhinoceros? The viceroy even summoned local caciques or chiefs to ask if they had heard of any similar living specimen in the region. The world still held unknown phenomena. The plains and pampas were largely unknown territories, not to mention Patagonia, a desolate land of legendary giants.

The Royal Cabinet of Natural History of Madrid had been founded only a decade before, thanks to the acquisition of the collection of Pedro Franco Dávila, a native of Guayaquil who had lived in Paris before coming to Madrid to direct the Royal Cabinet (see ‘Creole Cabinet’ in this volume). The institution was now looking for pieces and natural curiosities, filling its rooms with products and examples from Spain’s huge and diverse possessions abroad. The marquis of Loreto sent the bones of the unidentified beast. After crossing the Atlantic, contained in seven crates, the bones arrived at the cabinet in Madrid.

Once unpacked, from the end of 1788, Juan Bautista Bru, the cabinet’s taxidermist and painter, directed two projects that would ensure that the strange monster from Luján became more widely known. First was the assembly of the skeleton for its public exhibition in the cabinet. Then, a notable description was published in collaboration with engineer Joseph Garriga that included splendid engravings by the artist Manuel Navarro: the Descripción del esqueleto de un cuadrúpedo muy corpulento y raro, que se conserva en el Real Gabinete de Historia Natural de Madrid (Description of a Very Corpulent and Strange Quadruped, preserved in the Royal Cabinet of Natural History in Madrid).¹

The exhibition of the monster of the Luján River standing on a pedestal in the Royal Cabinet and the publication of images enabled it to circulate in the public sphere, a basic requirement of enlightened science. As in the Buenos Aires drawing, the taxidermist must have been thinking of an equine or perhaps a feline of great size: standing on its four limbs, its posture – unaltered today in the National Museum of Natural Sciences (MNCN) in Madrid – is very rigid. Bru is known to have cut and glued bones without great compunction, even adding the tail of a mule that, later, he removed.

The identity of the monster was a mystery. The morphology of the blunt head was fearsome. From its powerful jaws rose a molariform dentition, no doubt that of an herbivore. However, the limbs ended in sickle-shaped claws, sharp nails that looked like those of a carnivore. Now, where had a quadruped about five metres long ever been seen with claws and without fangs? Its anatomy suggested the mythological chimaera (a term used today for errors of interpretation, in particular when an extinct organism is identified from two or more fossil elements of different species) – this mythic beast had the head of a lion, the body of a goat and the tail of a dragon.

Its skull, noted Bru, suggested an ‘unspeakable monstrosity’. To look at it was ‘an eye-catching spectacle’, something ‘astounding and remarkable’. It provoked agreeable shudders, reminiscent of the ‘pleasing kind of horror’ described by Joseph Addison in The Pleasures of the Imagination.² The elevation of its bones, the spaces they formed, evoked the view of a ‘range of mountains seen from afar, on a clear and serene day when the horizon is clear of clouds’. It is the idea of the terrifying sublime, the sensation awakened when contemplating a precipice, a ruin or a cemetery. There was something of all this behind this massive skull that, in a way, was an authentic zoological vanitas, a vestige of a notion of ‘deep time’ that was only then emerging into scientific consciousness.

Before Garriga and Bru published the description of the skeleton, two foreign visitors to the Royal Cabinet had been fascinated by that ‘unspeakable monstrosity’. They reported its existence from afar, drawing upon or copying Bru’s preparatory sketches. One of these visitors was a Caribbean diplomat in the service of the directorate, Philippe-Rose Roume, who in 1795 was in Madrid negotiating the transfer of Santo Domingo from Hispanic to French dominion. He got hold of some copies of the prints that Bru and Navarro were then preparing and quickly sent them to the Museum of Natural History in Paris, where a brilliant young naturalist was about to solve the case without leaving his studio. There he had all he needed.

The young man in Paris was Georges Cuvier (1769–1832), the epitome of the cabinet naturalist. Unlike the travelling naturalist who sought direct knowledge of nature in the field, Cuvier’s knowledge was grounded in distance, study, abstraction and analogy. Celebrated years later as the father of comparative anatomy and vertebrate palaeontology, Cuvier’s method of identifying the Luján River skeleton heralded a new way of approaching the study of fossil remains. Without visiting Madrid, without observing the animal ad vivum, looking at the copied images of Bru and Navarro and working in the collection of skeletons in the Natural History Museum of Paris, perhaps the most complete collection of vertebrates of the time, Cuvier avoided the major obstacle, the greatest source of confusion: size. On paper, the problem of size vanished or was at least minimised. It no longer tricked the viewer. It is much easier to see similarities of form if one forgets dimensions. In no time Cuvier realised the affinities between the Río de la Plata skeleton and those of the much smaller edentates (Xenarthra), a family of animals that includes pangolins, armadillos and sloths.

A sloth of more than five metres? Only the edentates combined such dentition (no enamel, continuous growth, molars without incisors) with those non-ungulate limbs and powerful claws that for others had been so confusing. Cuvier published an article with these conclusions at the beginning of 1796. He baptised the specimen Megatherium Americanum, the ‘great American beast’, affirming that the skeleton belonged to a vanished animal, different from anything living today. The American beast came from an ancient world (ancien monde). But how ancient? And how different was this ancient world from our own?

The megatherium was one of the first in a long list of inhabitants of a lost world. The list did not yet include dinosaurs but instead the Siberian mammoth, the American mastodon, the Maastricht animal and the marsupial of Montmartre. Cuvier defended the theory of catastrophism, the idea of the existence in the remote past of one or several great crises of nature that had given rise to new worlds and different species. This theory was opposed to Charles Lyell’s uniformitarianism, the idea that the same conditions and alterations in Earth’s past were ongoing today. Lyell’s was a fundamental idea for the theory of evolution and natural selection. And yet, when Cuvier put into practice the correlation of the parts of the organism and the subordination of characters (in other words, applied the notion that all the organs and their parts are related to each other and depend upon the functions each performs), thereby applying the same laws for the study of living animals as for extinct ones, he paradoxically contributed to unifying the ancient world with the present one. The history of the Earth was freeing itself from the biblical story. There now arose a series of questions about the relationship between living beings and extinct ones.

Cuvier’s publication had precipitated that of Bru and Garriga, which included the splendid engravings the sketches for which had been made available to Cuvier. In the Descripcion, the authors commented upon Cuvier’s contemptuous attitude toward Spanish and Spanish American science. A vile Frenchman had scooped them. The case was another episode in the so-called Black Legend or negative stereotype of Spanish and Spanish American science cultivated in northern Europe, where Spain and its empire were frequently dismissed as backwaters of ignorance.

But the megatherium would have other afterlives. Before Roume had informed Cuvier of the find with copies of sketches, another diplomat had visited the Royal Cabinet of Madrid. His name was William Carmichael, and he was the representative of the nascent United States in Spain. After seeing the unidentified skeleton in 1789 while it was still in the process of being mounted, he informed Thomas Jefferson, then in Paris as plenipotentiary minister. He must have included some drawings. The author of the Declaration of Independence was more than just a natural history buff. He was very interested in fossil remains. Years before, he had dealt with the so-called beast of Ohio, the American incognitum, a species initially confused with the mammoth but which turned out to be another pachyderm, the mastodon. Engaged in heated debates about the nature of the New World, Jefferson defended its strength against the attacks of French, Dutch and British naturalists, who considered it to be inferior to and weaker than the Old World. When Jefferson received the reports from Madrid, he cannot have paid them much attention. In that year the French Revolution erupted. But in 1797 more remains appeared in his native Virginia. This time it was a Megalonyx (‘large claw’), a northern relative of the megatherium of the Río de la Plata. For a moment Jefferson thought that a feline of this size, a terrifying carnivore, could vouch for the vigour of the New World. It must therefore have proved disappointing for him to read Cuvier’s article, where ‘the great American beast’ was identified as a sloth, the most abject animal in Creation, according to Buffon, whose theory of New World inferiority was the great scourge of American patriots.

The utility of the megatherium did not stop there. The beast had been used to demonstrate catastrophism, the extinction of certain species and the dignity of Spanish and Spanish American science and was nearly recruited in the American campaign to defend the nature of the New World from Eurocentrism. Goethe now used the beast to sketch an idealised evolutionary history, identifying it as the descendant of a sea beast that had had to adapt to the primeval swamps. The epigeneticist and embryologist of Russian origin Christian Pander had it as a subterranean beast, a root digger supported by its two forelimbs, as illustrated by his collaborator, the German naturalist and engraver Joseph W.E. D’Alton (Figure 3). The Reverend William Buckland, a firm advocate of natural theology, used D’Alton’s image and assigned the megatherium a prominent role in making manifest the infinite wisdom of the Creator. Its ‘extraordinary deviations’, its ‘egregious monstrosity’, were in accordance with its behaviour and eating habits. The megatherium recovered the role of monsters in the ancient world: to demonstrate the divine plans of Providence.

It was Richard Owen who in the 1830s finally stabilised the species and assigned it a skin or fur. The megatherium differed from the glyptodon. It was not a Dasypus but a Bradypus, a species more like the sloth than the armadillo. It probably adopted a sitting posture and was occasionally close to bipedalism. Supporting itself on its forelegs, it used the hind legs to reach the branches of trees. This is how the megatherium is displayed today in the natural history museums of Paris and London. In Argentina it constitutes a national emblem and relic, a native species that played a prominent role in the establishment of Argentine palaeontology via the work of Florentino Ameghino toward the end of the 19th century. Meanwhile, the megatherium of Luján is still held today in the National Museum of Natural Sciences in Madrid, heir to the Royal Cabinet first assembled by the Peruvian Creole Franco Dávila. It remains an object of global knowledge, albeit now as a key to unlocking a lost history of science that connected Argentina with Madrid, Paris and Philadelphia.

FURTHER READING

Gould, S.J. (1987) Time’s Arrow, Time’s Cycle: Myth and Metaphor in the Discovery of Geological Time (Cambridge, MA: Harvard University Press).

López Piñero, J.M., and T. Glick (1993) El megaterio de Bru y el presidente Jefferson: una relación insospechada en los albores de la paleontología (Valencia: CSIC).

Pelayo, F. (1996) Del diluvio al megaterio: los orígenes de la paleontología en España (Madrid: CSIC).

Pimentel, J. (2017) The Rhinoceros and the Megatherium: An Essay in Natural History (Cambridge, MA: Harvard University Press).

Podgorny, I. (2011) ‘Diplomacia, pichiciegos, megaterios y gliptodontes, 1820–1840’, Ciencia hoy, 21 (121): 49–54.

Ramírez, F., and I. Podgorny (2001) ‘Las metamorfosis del megaterio’, Ciencia hoy, 11 (61): 12–19.

Rudwick, M.J.S. (2005) Bursting the Limits of Time: The Reconstruction of Geohistory in the Age of Revolution (Chicago, IL/London: University of Chicago Press).

Rudwick, M.J.S. (1997) George Cuvier, Fossil Bones, and Geological Catastrophes: New Translations & Interpretations of the Primary Texts (Chicago, IL/London: University of Chicago Press).

¹ J. Garriga, Descripción del esqueleto de un cuadrúpedo muy corpulento y raro, que se conserva en el Real Gabinete de Historia Natural de Madrid (Madrid: Viuda de Ibarra, 1796).

² J. Addison, ‘The Pleasures of the Imagination: Joseph Addison, from The Spectator (1712)’, A. Jenkins (ed.), Michael Faraday’s Mental Exercises: An Artisan Essay-Circle in Regency London (Liverpool: Liverpool University Press, 2008), 239–42.