Fossil fakes and their recognition

Joan Corbacho and Consuelo Sendino (Spain)

Ever since fossils first attracted the attention of mankind, they have been traded and, with the emergence of this commerce, so fossil fakes have appeared. The number of such fakes and their geographical origin has increased with time. On the one hand, this parallels the large demand for fossils; on the other, it reflects the outlawing of fossil sales in some countries, combined with the economic needs of many families, who use fossils as their main source of income. This trend will continue, as the supply of genuine fossils diminishes due to trading restrictions. In particular, it will continue as borders, which were once freely open to nomadic movements become heavily policed, along with a decrease in open collecting sites.

History of fossil fakes

Fossils have been used for more than 400,000 years, some as tools and others as fertility symbols. For example, fossil echinoids were found in the early Neolithic site of Ain Ghazal in Jordan and at a Neolithic site in County Kerry in SW Ireland, where they were used as funeral adornments for ceremonial purposes. In addition, bracelets made of fossil shells were excavated at a Neolithic site in Vinca-Belo Brdo in Serbia.

It is apparent from these examples that fossils were used by early Europeans to produce items of social value that could be traded. Therefore, it is not surprising that fossils have been faked for a long period of time. One of the most striking fossil frauds, rivalling in fame the ‘Piltdown Man’ fraud from Sussex in England, happened at the beginning of eighteenth century and was carried out by colleagues of Johann Bartholomew Adam Beringer (1667–1740) (Taylor 2004).

Beringer, who was Dean of the Faculty of Medicine at the University of Würzburg, was very interested in the study of “formed stones,” as a testament to the Biblical Creation. However, his personal arrogance provoked two of his colleagues to organise a massive fraud involving the manufacture and sale to the hapless Beringer of more than a thousand fraudulent fossils. These he depicted in twenty-one engraved plates in his book Lithographiae Wirceburgensis (1826) (Plate 1; Fig. 1 (Left)). When Beringer discovered the deception, he initiated a court action against the perpetrators. He never published again on fossils, though a modern German palaeontological journal – Beringeria – honours his name.

A well-known fossil fake used by Creationists to argue against evolution comprised supposed fossilised human footprints. These were found among Cretaceous dinosaur trackways in the 1920s and 1930s on the banks of the Paluxy River at Glen Rose (Texas, USA) by George Adams, a Creationist with a reputation for making fraudulent fossils (Fig. 1 (Centre)). In 1970, Wayland Adams, a resident of Glen Rose, explained to the media that his uncle, George Adams, had carved the fake human footprints to demonstrate a technique for carving slabs with a hammer and chisel, and had applied muriatic acid and manure to age the specimens artificially.

Another fake with importance for evolution is Archaeoraptor, a supposed new genus found in China, details of which were published in National Geographic Magazine in 1999. This fossil fake seemingly represented additional proof of the link between birds and dinosaurs. The discovery of Archaeoraptor was a major item of world news. The journal announced the fossil to be “the lost link” between birds and theropod dinosaurs.

However, even before publication, there had been severe doubts about the authenticity of the fossil. Archaeoraptor became a scandal when it was demonstrated to be a composite made from true fossils belonging to three different species. Zhou et al. (2002) confirmed that the major part of the fake, the body, really belonged to a primitive fossil bird, Yanornis, but the tail was from the dromaeosaur, Microraptor, which had been described by Simon (2000). The limbs belonged to an animal still undetermined (Fig 1 (Right)). The scandal of Archaeoraptor drew attention to the illegal traffic of fossils in China. However, although this was a fake, there are many true examples of feathered dinosaurs that show the close evolutionary relationships between birds and theropods.

In general, we can distinguish two different kinds of deception – ‘fossils’ that have been completely or partially manufactured and true fossils for which a false provenance has been claimed. An example of the latter is provided by the work of Professor Vishwa Jit Gupta of Panjab University at Chandigarh in India (Talent 1989). Gupta bought fossils from various sites around the world, claiming that he had found all of them himself in northern India. This misled several sincere scientists with whom he collaborated to make incorrect conclusions about the palaeogeographical distributions of numerous taxa.

Increasing fossil commerce

Countries where fossil fakes are common include Peru, Colombia, Russia, USA, Germany, France, and (especially) Morocco and China. The biggest markets for these fakes are in the USA, Morocco and China. The US market is also the leader in the trade of fakes and the Internet provides a ready source for them. Sale and auction websites on the Internet are an ideal way for selling fake fossils. Other outlets for selling fake fossils are the numerous mineral and fossil fairs organised around the world, and the more important the fair, the larger the number of fakes.

Fairs in Germany have the best controls to avoid the fraudulent sale of fakes as genuine fossils. Thanks to authenticity controls, fake fossils can only be sold as copies in Germany and not as real fossils, as often happens in Morocco. An important fact to emphasise is that, since China became open to commerce, fakes have increased by more than 500% as a result of the massive demand for Chinese fossils. The variety and magnitude of Chinese fake fossils is endless. They include every kind of forgery, from fakes made of pieces of different specimens (dinosaurs, turtles and crocodiles), to copies made completely of plaster (turtles, crocodiles and sabre-toothed cat skulls). This market is fuelled by the shortage of complete, genuine fossils, with those originals that do exist commanding high prices.

Different kinds of fakes and how to recognise them

Contemporary fossil fakes can consist either of specimens that are entirely faked or are partial fakes, typically being carved in sediment or made of diverse parts from different specimens that may belong to different species. We will describe these types with the aid of particular examples, citing the analytical methods that can be used to recognise the fakery (Figs. 1 to 3).

Specimens that have been faked completely can be carved in the sediment, manufactured from different materials such as resin or concrete, or even made from pieces of different individuals or species. Examples abound of fake fossils made of resin and later mounted on and partly covered with sediment. A slab of shale from China with two individuals of supposed Keichousaurus (a marine reptile) made with resin exemplifies this type of fake (Fig. 2a ). It is possible to expose the fraud simply by placing such specimens in a bath of acetone or by using a soldering iron to reveal that resin has been used. The slab of Keichousaurus was obtained thanks to a Chinese friend, who believed it was authentic. It is now housed along with many other fakes described in this article at the Museu Geològic del Seminari in Barcelona. The same technique has been used in China to fake specimens of Sinohydrosaurus (a freshwater reptile).

Another example, this time of Moroccan origin, is of a specimen of the trilobite Andegavia sagittapeltis that was mounted in resin above a sediment matrix (Fig. 2b). This kind of fake is the most frequent in Morocco. It is possible to detect by applying the point of a soldering iron which melts the resin, giving off a distinctive odour. Another test is to look for holes in the resin using a magnifying glass. These represent trapped air bubbles. If such specimens are placed in acetone, they will turn completely white in less than 24 hours. A second example of Moroccan origin is a striking fake of the trilobite, Zlichovaspis, on a sediment mount (Fig. 2c). This was claimed to be authentic by the seller in Rissani in eastern Morocco.

Other examples that can be seen on the Internet (for example, eBay) include imitations of dinosaur egg nests produced in China. The eggs are made of concrete, topped with pieces of real eggshells from different specimens, in a matrix of compressed earth. For example, Fig. 2d shows a Hadrosaurus egg nest. The fakery can be exposed by detailed surface observation or by using X-rays. This kind of fake is very common. A very good fake of Chinese origin consists of the Chinese trilobite Drepanura, which has been carved and polished using acid, making the fraud very difficult to discern except by an expert on trilobites (Fig. 2e).

The story of this piece started when, believing in its authenticity, the specimen was purchased for an Australian museum during a trip to China. The buyer later sold it to one of us on an Internet auction website. The fakery is not detectable using acetone or a soldering iron, and even with X-rays, it is difficult to identify. The only way to detect this fake is with the help of an expert able to recognise the substantial difference in the morphology of the trilobite under a microscope, where the marks of the sculptor can be seen.

Perhaps the strangest fake offered for sale on the Internet is a Bolivian specimen that represents a hypothetical trilobite with a reptile on top of it. This is made of clay and was offered as a “valuable fossil” (Fig. 2f). Another mischievous fake comes from the Lebanon and comprises ‘fossils’ painted directly onto the rock (Fig. 2g). They were bought in an Internet auction. Simply by applying acetone or even through careful observation under a hand lens, they could be seen to be fakes. There are other supposed fossils trapped in amber. Insects, amphibians and reptiles in ‘amber’, among other animals, are sold on the Internet as though they were real fossils. The coarse specimens figured here come from Istanbul (Fig. 2h to i).

A good example of a fake fossil made from pieces of real specimens is represented by the apparent skull of a Moroccan crocodyliform, Dyrosaurus (Fig. 2j).This skull is made of plaster mounted on a sand matrix. It has real teeth, but from different specimens. First impressions suggested that it was not a genuine fossil and X-rays confirmed this conclusion.

From the insect world comes a kind of fake very commonly found on the Internet. It is based on ‘fossil’ dragonflies made of resin mounted on top of a rock matrix, or made with various pieces from different specimens (Fig. 2k). Most of these come from China. You can also find on the Internet fake fossil birds made from resin in a rock matrix, or consisting of different fossil bones from various species mounted in a rock matrix (Fig. 2l). They are sold as authentic and are also mainly made in China.

Another fraud carried out on an important auction website concerned a septarian concretion sold by an American seller to a Spanish collector as a dinosaur coprolite (Fig. 2m). This is easily recognisable as a concretion by any experienced geologist. A curious anecdote concerning this specimen is that there exist some papers ratifying the authenticity of the specimen to a Spanish local museum, where this ‘coprolite’ of an unknown species of dinosaur is much admired.

A huge variety of fossils have been partially faked in different ways and to different extents. When specimens have been minimally ‘repaired’ they can be regarded as real fossils, but they are considered to be fakes in cases where anatomical parts have been reconstructed. However, if the fossil has been reconstructed by less than 10% and this reconstruction has not affected an area key to the species diagnosis, then it is not considered a fake.

Reconstructed ammonites are especially common at many fossil fairs. These are mostly small fragments that form the bases for larger reconstructions. It is very easy to find on the Internet fakes of the ammonite Heteroceras, based on small, original fragments with the rest made from carved stone and glued to the original part (Fig. 3a). These are usually of Moroccan origin and can easily be detected as fakes through careful observation.

It also is common to find highly reconstructed teeth of sharks, normally Carcharodon megalodon, from the Atacama Desert in Chile. Some are more than 80% genuine, with only the root replaced by resin and later painted to disguise the fakery (Fig. 3b). This kind of fake can be revealed with a soldering iron or other point of heat. In Morocco, the gums of sharks’ teeth are made using plaster, whereas resin may be used in the case of dinosaur teeth and claws.

Abundant examples can be found of trilobites that have been partially reconstructed without a major effect on their anatomy. These reconstructions can be exposed using ultraviolet light, with clearer patches corresponding to the resin used to repair the fossil (Fig. 3c). Such specimens are more common than completely faked trilobites. Other specimens are real, but have been placed on a matrix that has nothing to do with the original matrix. This is very common among Russian fake trilobites (Fig. 3d) – the trilobite is authentic but it sits on a rock matrix that does not belong to it. Although the palaeontological context is lost by this process, the specimen still has commercial value. The best method to detect this sort of fakery is to apply a soldering iron to the join between the fossil and matrix.

Some fossil fishes fall into the category of partial forgeries. There are many examples of authentic fossil fish mounted on a sandstone matrix. For example, Fig. 3e of Aspidorhynchus comptoni comes from Brazil. Such fakes are normally made in Italy, have a commercial value, and are sold as aesthetic specimens for display. These fossil fishes would generally be found in nodules. Sometimes, the tail is not preserved and is reconstructed using resin (Fig. 3f). More often, the fish has been constructed from pieces of different specimens – the bones, tails and fins especially (Fig. 3g). Fakes like this are manufactured everywhere. Alternatively, the ‘fossil fish’ may be entirely painted or carved (Fig. 3h).

Methods and tools to detect fakes

As discussed above, long established methods and tools, as well as more modern techniques, can be used to detect fake fossils. Detailed study of the specimen under an optical microscope is a good starting point. If this is insufficient, chemical analysis, reflection behaviour and X-rays can help to recognise fake fossils. Computerised axial tomography (CT scanning) is a new technique that has been added recently.

Chemical analyses used to discern natural from artificially cemented matrix can be made using formic acid, hydrochloric and acetic acid diluted to 20%, 33% and 20%, respectively. In the case of fakes, the matrix and the fossil react, producing small bubbles. For fakes made with resin, which can be in the fossil or between the fossil and the matrix, a soldering iron can expose the presence of resin, and acetone will reveal any paints used to mask the resin. This method is very useful for fake Russian trilobites.

Reflectivity varies between the specimen and the faked matrix when viewed in ultraviolet light (Fig. 3c). Minerals of different composition behave differently under short and long wave ultraviolet. This method is also valuable in distinguishing between specimen assemblages of diverse origin. However, X-ray techniques are recommended for being more reliable and providing the most economic option relative to the quality of the results. With X-rays, it is possible to differentiate the authentic part of the specimen from the fake by density differentials (Fig. 3i).

CT scanning also helps to discern the density difference between the faked and the genuine parts of the specimen, which may be imperceptible to the naked eye. This technique has been used to verify the authenticity of a skull of the dinosaur Psittacosaurus from the Cretaceous of China, now housed at Naturalis in Leiden, Holland (Fig. 3j).In addition to these conventional analytical technologies, newer methods are constantly being explored for use in the detection of fake fossils. Non-invasive examination methods, using ultrasound and eddy current methods, optical coherence tomography, and optical scanning techniques, have all proved to be very useful. High-resolution images, multi-spectral imaging and analogous hyperspectral imaging can also be used to identify pigments and to detect colour changes as specimens fade when displayed.

The traditional tools are binocular microscopes, lenses, ultraviolet light (used to see reflectivity), acetone and soldering irons. Microscopes are very useful in distinguishing different materials in the sample, whereas lenses (10 to 30X magnifications) are sufficient to detect holes in resin, or whether specimens have been painted or carved. A lens has been found to be very helpful when studying trilobites and other spiny fossils, to see if the spines are broken and if they really belong to the specimens.

Acetone is of great value in discriminating between real fossils and fossils faked with resin (epoxy). Specimens should be placed in acetone for several hours to observe the complete whitening that proves the use of resin. In cases where the specimen has been carved in the same matrix and later painted, application of a paintbrush dipped in acetone can be used to confirm the fakery.

Conclusions

It is worth highlighting the diversity of fossil fakes that are currently available on the commercial market. These can be found for sale not only in shops and fairs, but also on the Internet. The latter has become an efficient way of spreading these specimens globally, both to individuals and to museums. Fakes are made mainly in China and Morocco, but are sold principally through the USA and can be partial or complete fakes.

Copies of fossils are acceptable, but only if they are identified as replicas and not advertised as real fossils. We also note that repairs to fossils are acceptable up to a level of 10%, but only if the repair is not to an important part used to identify the fossil and its presence is disclosed by the vendor.

References

Simon, L. M. 2000. Archaeoraptor Fossil Trail. National Geographic, 198 (4), 128-132.

Talent, J.A. 1989. The “Misplaced” Fossils. Science 246 (4931), 740-741.

Taylor, P.D. 2004. Beringer’s iconoliths: palaeontological fraud in the early 18th century. The Linnean 20 (3): 21-31.