How to Tell If a Fossil Is Authentic
When discussing fossil specimens, the most common questions revolve around their authenticity and how we can tell whether they are original or replicas. Many people find it hard to believe that they can actually hold a genuine museum-grade artifact, millions of years old, in their hands. This hesitation often holds people back from starting their own fossil collection, making it essential to understand the key criteria used to determine whether a specimen is authentic.
Types of "Fakes" in Fossil Specimens
Before discussing how to determine whether a fossil is authentic or not, we must establish exactly what is meant by "fake." Below is a list of modifications and restorations applied to fossil specimens, ranging from standard enhancement procedures to deliberate attempts at forgery:
- Repairs – many fossils are fractured or damaged during excavation, and preparators use Paleobond (a specialized adhesive available in various viscosities for fossils) to repair the specimens. These types of repairs ("field repairs") are completely standard and to be expected.
- Restorations – during the preparation process, certain parts of the fossil may be missing, and preparators may restore the specimen by filling in or recreating those missing elements. This is typically done by sculpting and attaching the missing parts (e.g., the spines of a spiny trilobite) or by filling a crack (e.g., in a bone) with glue, epoxy, or wax. There is nothing wrong with these restorations as long as they are fully disclosed to the buyer.
- Enhancements – a series of enhancements are often performed on a fossil specimen, such as painting or polishing. Although enhanced specimens remain original fossils, these types of treatments significantly reduce their scientific value while improving their visual appeal for collectors (e.g., polished ammonites, polished orthoceras).
- Composite specimens – certain preparators and collectors may assemble parts from different individual animals of the same species (e.g., the digits or phalanges of a dinosaur claw) into a single complete specimen. These types of composite fossil specimens are common and frequently displayed in museums, helping the public visualize the complete animal in the absence of a fully intact specimen. There is nothing wrong with composite specimens, but dealers should inform the buyer that the fossil is a composite prior to purchase.
- Reconstructions – large fossil specimens, such as those of dinosaurs, are most commonly found disarticulated. These original yet incomplete specimens may have missing parts (e.g., a section of a vertebra or a femur) fabricated entirely from resin or crushed fossilized bone. These recreated portions are referred to as reconstructions. Similarly, missing limbs or flippers on Keichousaurus fossils from China may simply be painted onto the matrix. As with composite specimens, as long as these reconstructions are disclosed to the buyer prior to purchase, there is nothing wrong with them.
- Fossil replicas – fossil replicas are typically cast from famous museum specimens and are striking yet affordable items, making them more accessible for enthusiasts to collect. Replicas can be molded directly from a museum specimen. Paleontologists often encourage people to buy replicas, as this generates revenue for museums without restricting public or scientific access to specimens that may hold significant scientific value. However, it is essential that replicas are clearly labeled as such prior to purchase.
- Falsified specimens in total – last but not least, there are also completely fake fossil specimens. These are fossil specimens manufactured to imitate original specimens and sold as authentic fossils, in order to mislead and generate profit. They can be made of resin, carved from limestone or even genuine fossilized bone, or they can simply be painted on a stone matrix. Usually, fakes are easy to spot, as it is difficult to reproduce the complexity of the details of a natural fossil specimen and the technique used is rudimentary and similar for all of the seller's specimens, which gives them away. Due to the amount of work required, fake fossil specimens are most often made of spectacular, very rare and expensive specimens (several thousand euros per specimen), common fossil specimens being cheaper to find than to fake.
How to Identify a Fake Fossil?
There are several tests used by specialized institutions to authenticate fossil specimens, but they are generally very expensive – CT scans, X-rays, acid tests, radiometric dating, or chemical fluorine analysis. Since most people do not have access to such tests, and some of them have destructive effects on the specimen, there are nevertheless a few key factors that a new collector can consider when purchasing a fossil to determine its authenticity:
- Diversity – just as every organism is distinct from another, even within the same species, every fossil is unique. Fossils may look similar, but no genuine fossil is 100% identical to another. A seller's entire inventory should be examined to observe the variety among their specimens. If you notice specimens that are 100% identical, they are unequivocally fakes.
- Details and defects – the level of detail and natural imperfections of an authentic fossil specimen are extremely difficult to replicate using plastic or resin – wear patterns on teeth, partially damaged enamel, fractures, cracks, leftover uncleaned sedimentary matrix, etc. At the same time, certain fine morphological details are remarkably hard to imitate – the intricate structures of a trilobite's compound eyes, the serrations on a Megalodon tooth, growth rings on bones, as well as their delicate porosity. The presence of such details on a specimen strongly supports its authenticity. Conversely, there are also defects resulting from the excavation process. Fossil hunters frequently rely on heavy methods to extract specimens – effectively using sledgehammers or even explosives to split rock. Consequently, many fossils – particularly Devonian trilobites from Morocco, due to the hardness of the limestone in which they are embedded – typically feature a fine break line running through the body that is subsequently repaired. These field breakages caused during collection serve as another reliable hallmark of authenticity.
- Physical and geometric properties – authentic fossils are composed of dense, compacted stone, which is significantly heavier than the plastic or resin used to craft fakes. Furthermore, a fossil's coloration is generally uniform, and its natural texture is difficult to duplicate. Casts have a distinct texture compared to genuine fossils—feeling either overly porous or unnaturally smooth—and may exhibit color inconsistencies, visible glue seams around their perimeter where they were attached to the matrix, or telltale air bubbles from the casting process. The geometry of fake fossils carved directly into limestone is often rudimentary because the carvers work quickly, making the precise geometric perfection of a natural fossil exceptionally hard to achieve on a quick turn.
- Price – There is a wide array of very common fossils available at accessible prices: ammonites, certain common species of trilobites, Mosasaur teeth, Plesiosaur teeth, teeth from specific dinosaur species (Spinosaurus, Triceratops, Edmontosaurus), teeth from Megalodon and various other sharks, dinosaur eggshell fragments, orthoceras, petrified wood, etc. These fossils are found in abundance in certain deposits and carry limited scientific significance, sometimes even being sold directly by museums. Purchasing a fossil of this nature rarely presents authenticity concerns. The risk of forgeries or undisclosed restorations increases with rarer and more expensive specimens valued at thousands of euros, where the labor required to produce a fake is financially justified.
- Provenance – In many cases, the information that comes with a specimen can be an extremely important factor in determining its authenticity. This data provides very useful information for collectors and helps to verify the authenticity of the fossil. For example, does the location of provenance mentioned correspond to the appropriate geological age for that type of fossil? Does the seller have the necessary knowledge about the specimens they are selling, so as to be worthy of the buyer's trust?
- Tests – These can be either non-intrusive or intrusive. Fossils restored with resin, epoxy, or plastic may glow under a UV lamp. Composite bone fragments from different sources may show noticeably different color hues under blacklight. Resin and plastic are also softer than stone, a property that can be detected using the sensitive nerves in your teeth if you apply a light bite. A drop of acetone can remove paint (a very useful test for modern mammal bones artificially aged to look like fossils), allowing you to see if the color transfers onto a cotton pad—though this would be considered an intrusive test. Authentic Mosasaur teeth are frequently glued onto fabricated roots or composite jaws made of crushed bone to inflate their value. Rubbing them with a damp cloth can dissolve the water-soluble glue. As an extreme measure, knowledgeable collectors have been known to slice specimens in half to reveal the inner resin composition! Amber is another type of fossil that is frequently faked, sometimes made of plastic, and other times crafted by inserting very rare inclusions (spiders, large insects) between pieces of genuine amber that are then fused together. Real amber is warm to the touch; rubbing it with a soft cloth causes it to emit a natural scent and charges it with static electricity, though it can also cause it to begin melting. Additionally, amber floats in seawater or saltwater (which is how it is collected in the Baltic Sea), whereas copal (young amber) and plastic sink. Amber is hard and fractures when cut, while plastic can be sliced smoothly without cracking. A drop of alcohol or acetone will begin to dissolve copal, but will not harm genuine amber. A hot needle easily penetrates copal, produces a black spot and foul-smelling smoke on plastic, and penetrates authentic amber only with difficulty while yielding a faint whitish smoke.
- Known fakes – there are also a number of fossils that are frequently forged, such as certain very rare trilobite species from Morocco, Mosasaur jaws (where the teeth themselves are genuine but the jawbones are composite structures), Keichousaurus fossils, feathered dinosaurs, and intact dinosaur eggs from China. Any novice collector should exercise heightened caution when considering the aforementioned fossil types.
In conclusion, for beginner fossil collectors, it is recommended to start with common, rarely forged specimens – ammonites, common species of trilobites, Mosasaur teeth, Plesiosaur teeth, teeth from specific dinosaur species (Spinosaurus, Triceratops, Edmontosaurus), Megalodon and other shark teeth, dinosaur eggshell fragments, orthoceras, petrified wood, etc. – and subsequently diversify the collection as experience is gained.
Sources: American Museum of Natural History, fossilmuseum.net – Study 1, fossilmuseum.net – Study 2
