economic value of rare fossil specimens has fuelled their market value, firing
the imagination of fossil dealers and collectors and increasing demand for
fraudulent specimens. The production of fake fossil specimens is particularly
common in poorly developed areas where fossil trading can represent one of the
few ways to achieve economical survival. For example, China and Morocco are
known to produce both genuine and fraudulent fossils, making the detection of
fake all the more difficult (Dalton, 2000, 2004a, 2004b, Milner et al. 2001,
Padian, 2000). Because complete specimens are rare, they command higher price.
For this reason, forgers often find it profitable to join multiple specimens in
order to assemble a fraudulent single skeleton that appears complete. Padian
(2000) discusses in some detail the problematic nature of fossil trade and
forgery with respect science and education in the United States.
A subject of
shame and embarrassment for the researchers involved in their study, certain
frauds have been divulged to the public. For example, the famous “Piltdown Man”,
a forgery merging a modern human skull with the jaw of an orangutan, was
advanced as a single specimen of a putative primitive human ancestor that fooled
anthropologists for decades (Weiner, 1955).
One of the most
conspicuous recent examples of fraudulent composite dinosaur fossils is the
famous Archaeoraptor specimen from the Liaoning Province of China. This
“discovery” was the subject of coverage by media sources including National
Geographic and Nature (Rowe et al., 2001; Sloan, 1999; Zhou et al., 2002).
Careful examination subsequently revealed that the specimen represents at least
two and up to five, separate specimens that were fraudulently merged to assemble
a single “individual” (Zhou et al., 2002).
are usually forged to obtain not only profit, but also publicity. Cunning
forgers may put much training and effort to render hoaxes as realistic as
possible. Some forged fossils are fantastically verisimilar to real fossil
specimens and may easily fool an incautious fossil-buyer.
The aim of this
paper is to give the method of fraud recognition. The goal is to discuss a
methodology to detect frauds, and not to discuss a buying setting, ethical
behaviours or even to recommend how to buy fossils.
WHAT IS A FOSSIL FRAUD?
degree of fossil authenticity is broad, ranging from unadulterated fossils, to
enhanced or merged original specimens, to complete forgeries containing no
fossilized material at all. Milner et al. (2001) report several cases of
sculpted “fossils” from Asia, particularly from China.
fossil specimen is an object that has been artificially transformed in order to
deceive potential purchasers that it represents a genuine, unaltered fossil.
There are three
main kinds of hoaxes:
1) Those that
contain no original fossil material, such as shapes carved in rock;
2) Those that
do contain original fossil material, but are entirely or partially altered in
order to give the appearance of a more complete specimen (example: a sculpted
carved skull from a fragment of a limb-bone);
3) Those that
are true fossil but artificially combine from multiple individuals (mostly from
the same species). Many of the most successful frauds are half-faked by
incorporating general fossil material to form a chimera. Such frauds are more
difficult to detect because they create “Frankenstein specimens” in which
several specimens are joined to form a single individual, a term evoking Doctor
Frankenstein’s monster created from parts of several human individuals in the
1818 novel by Mary Shelley. The chimera from the Greek mythology had different
species parts: lion head, posterior body of snake and main body of a goat, while
Frankenstein’s monster was a human made from parts of other humans.
HOW TO DISTINGUISH FAKE AND REAL?
a real fossil from a fraud can be difficult. Although many fraudulent fossils
seem authentic at first glance, with experience, one can distinguish a fraud by
simple observation. For those without such experience, a few simple but
effective techniques assessing specimen authenticity are suggested here,
including CT-scans, acids, and UV-light.
examination is capable of catching most attempts at fossil fraud. “Frankenstein
fossils” can be distinguished with the naked eye, or with the assistance of a
microscope. Such fossils comprised of multiple individuals merged into a single
specimen can be detected by identifying colour differences associated with
differences in preservation. Colour differences can be relatively minor, with
one bone slightly darker than the others, or major, preserving range of
different colours. Although such forgeries can seem realistic to the untrained
eye, certain types of colour differences within a given specimen are not
natural, and present a good indication that the specimen is suspect.
completeness of a fossil skeleton can be the first key in detecting a fraud.
Although genuine complete fossils are not unknown to science, it is important to
realize that such fossils are rare and valuable. Not coincidentally, it is this
rarity which encourages the forgery of complete skeletons. Imperfections in
fossil specimens are often filled in with waxes, glues or other materials (fig.
1). Such media can be used to attach two dissociated specimens, or to replace
bones entirely. Detection of these forgery techniques is often facilitated by
using a stereomicroscope or binocular lens, whereby waxes are easily
distinguished from true bone based on their surface textures, reflective
properties, and colour patterns. Wax or glue can also be distinguished from bone
by scratching the surface carefully with a needle or airscribe. Bone tends to be
harder and more brittle than wax and inconsistencies in texture and scratch
properties can often reveal areas for concern.
assembled Psittacosaurus scapulocoracoid based on genuine bone. Note the gap
refilled by wax. The middle part of the shaft is slightly darker and the cracks
are reddish, in contrast with the brownish cracks seen on other aspects of the
specimen. The crack shown in the inset is also unnatural: it stops abruptly
where the bone is completed by wax (specimen from private collection).
often smoothed with sandpaper to blur the interface between true bone surface
and filler materials. Whereas fossil bone surface texture tends to be coarse and
rough, fossil bones treated in this manner take on a polished surface texture,
devoid of natural imperfections. Excessive sanding may also reveal the internal
cortical bone texture. In figure 2, the premaxillae were sanded flat.
assembled Psittacosaurus skull based on genuine bone, in anterior view. The
original bone was sand-papered.
bones, especially in the skull, are difficult to falsify and are often absent in
forgeries. Forgers often use parts of real cranial bones in combination with
other bone fragments (cranial or not) to create a skull-shape, often quite
realistic at first glance. To complete the picture, forgeries are often encased
in mixtures of sand and the actual rock matrix encasing true fossils. For
example, mosasaur bones and teeth from Morocco have been falsely assembled to
create a tooth bearing jaw. Cementing matrix around such forgeries often makes
them look more authentic, and teeth can even be prepared out of the matrix
without it being obvious that the encasing “rock” is artificial. The false rock
matrix has a more plastic consistency, and the interstices may retain wax or
glue remains, which may be detectable during the regular preparation process
chemical analysis can easily detect such frauds. Several acids, including formic
acid (HCOOH, diluted to 20%), hydrochloric (HCl, diluted to 33%), acetic acid (CH3COOH,
diluted to 20%), can be applied to differentiate natural from artificially
cemented matrix. True rock matrix and bone often reacts to the HCOOH and HCl,
with small bubbles appearing on reactive surfaces upon application. In contrast,
most waxes, glues and artificial infill substances do not react to these acids.
This convenient and inexpensive test can provide nearly instantaneous detection
of false materials. In addition, because many glues and waxes are inflammable, a
simple lighter test can be used to detect the use of such materials in suspected
forgeries. In these cases, glues and waxes often burn or melt when exposed to
flame. Finally, acetone and other powerful organic solvents can be useful in the
detection of artificially cemented material associated with a suspect specimen.
These can easily reveal any paints, in addition to glue and wax that can be
combined with matrix silt or powder, to provide a natural-looking finish on
forgeries. Applying to the bone just a few acid drops or exposing to fire
locally and during just a few seconds is, in most of the cases, sufficient to
detect frauds and keep integrity of the fossil, without damaging it.
Tomography (CT) and X-ray analyses are effective techniques to detect hoaxes,
and the use of such medical tools has been increasingly common in every day
scientific research. Radiographic analyses detect differential densities of
bone, rock, and other materials. Fossil bone and rock matrix are most of the
times higher in density, which is normally depicted in the X-ray or CT film by a
lighter colour. CT and plain film x-rays can reveal areas of low density on a
given specimen (in darker colour) as potential areas of artificial wax or glue
infill that are less apparent to the naked eye. The figure 3A shows the example
of a Psittacosaurus skull X-ray in lateral view where the true bone is mainly
white, the rock in pale grey and the wax and glue is invisible or dark grey
under the x-ray. The figure 3A and 3B shows respectively a femur and a sacrum
where the bone gaps seen under the X-ray represent the parts filled artificially
not easily detected by a naked-eye surface examination.
CT-scan of assembled
skull (A), femur (B) and sacrum (C) of Psittacosaurus. Most of the bone is real,
but gaps between fragments were filled with wax that is not visible in the scan
due to their low density. The core of the “skull” is comprised of a rectangular
stone, with genuine bone fragments glued around it. CT-scanning was conducted at
the Clinic Cedima, in Caldas da Rainha, Portugal.
Because of different
material reflection under ultraviolet light (UV), also known as black light, a
composite specimen will glow with different colour and tonalities when seen
under UV light because the mineral composition fluoresces
differently under short wave ultraviolet versus
long wave ultraviolet. Such technique is useful to distinguish original bone
from the false matrix and to distinguish the bones from different proveniences.
The figure 4 the colour of the bones of the psittacosaur skull in dorsal view
are pinkish and green, which may represent true bone collected in different
localities (therefore different mineral composition and dissimilar UV
fluorescence) or larger concentration of waxes and glues. In this case the true
dinosaur bone fluoresces in pink. Although effective in most cases, this
technique does not always works because in dependent on the differential
composition of the minerals.
This is a
general overview of techniques. More details about these techniques should be
found and experts consulted about them, if needed.
Psittacosaurus skull under ultraviolet light. Different colours indicate
different bone origins and filler materials.
context is also relevant to understand the veracity of fossils. Fossils have a
high likelihood of being forgeries when they are available at low prices in
tourist shops and local markets where professionals are unlikely to visit.