Fossil replicas are made for a variety of reasons. The goal of replicating fossils is to reproduce the information contained in the original as completely as possible without damaging the specimen. Replicas are made from real fossils, traditionally using a mold and cast method, where a detailed mold is created from the original fossil and then filled with resin or plaster to form a cast. Advanced techniques like photogrammetry, laser surface scanning, or CT scanning can also be used to create accurate reproductions.
Why create replicas? There are 2 main reasons for this. First of all, many fossil types are rare. Despite all the fantastic dinosaurs you can see in museums, complete (or nearly complete) skeletons are exceedingly rare. Not every museum has the money to buy a real fossil, or the ability to go out into the field and dig up their own, so they must rely on casts. If not for casts, very few people would be able to see the specimens. Most often skeletons are found with bones missing or smashed. Fossil replicas and casts allow for these missing parts to be filled from other partial skeletons, which is called a composite skeleton. These can be made from skeletons that are incomplete, so some bones are real, some are not. And of course, when we do find one of those exceptionally rare complete or near-complete fossils, casts allow them to be shared with the world. And finally, fossils are a terrible combination of being both extremely heavy and extremely fragile. It can be very difficult to mount a skeleton in a way that isn’t going to damage the specimen, especially if they are fragile. For this reason, museums will sometimes put the cast on display, and keep the original specimen in the collections to preserve it. Also, replica fossils can also be sold to collectors who want to add specific species elements to their display, without losing a high-quality specimen from science.
Molds are generally made in silicone, polyurethane, or latex rubber. Each material has different properties and characteristics. Silicone is used where replication of very fine detail is important. However, it is easier to tear, making it less practical for extremely large molds. Latex is used where detail is not as important. It is difficult to tear and may even break the bone before tearing. By understanding these materials and techniques, most fossils can be successfully molded without harm.
Photogrammetry is a technology that delivers a 3D image of a surface by combining multiple photos of it. 2D camera shots are processed by photogrammetry software, with many factors considered, primarily the camera’s focal length, positions and angles of the camera. Photogrammetry can measure surface details and dimensions of fossils, even small ones, and digitally archive them. 3D data can be easily transmitted, allowing researchers and the public to share information about rare specimens. Photogrammetry can improve access to scientifically important objects without risking damage to fragile specimens.
The field of paleontology has transformed in the last few years because of the developments in 3D scanning technology and rendering software that have enhanced the quality of virtual models. 3D scanning can provide depth maps in a non-invasive, non-contact manner which is attractive for studying paleontological specimens due to their delicate physical properties. The application of laser scanning to Paleontology produces 3D fossil replicas that paleontologists can process, catalogue, study and share without the risk of damaging or destroying the original specimen. It also makes it possible to communicate their findings in an exciting and effective way, with applications to teaching and interactive museum displays.