Ersatzfossilisation

Ersatzfossilisation refers to fossil-like objects produced by non-biological processes or by artificial means that substitute for genuine fossilization. The term combines ersatz (substitute) with fossilisation and is used mainly in German-language discussions to contrast true fossil preservation with imitation or replacement phenomena. In natural settings, ersatzfossilisation can describe pseudofossils—structures that resemble fossils but do not preserve original biological tissue. These include concretions that form around an organic core that later decays, mineral precipitates that create shell- or bone-like morphologies, and other diagenetic patterns that imitate anatomical features. Such specimens can be mistaken for real fossils, necessitating careful morphologic, mineralogical, and chemical analyses.

In teaching, museums and some experimental studies, ersatzfossilisation also denotes the creation of artificial fossils or fossil-like replicas intended to demonstrate fossilization processes or to provide safe teaching materials. These replicas may be made from silicone, resin, plaster, or 3D-printed materials and are designed to resemble genuine fossils in external form.

Discriminating ersatzfossils from true fossils relies on multiple lines of evidence: absence of original organic material, microstructural differences, geochemical signatures inconsistent with biogenic tissue, and dating results. Related concepts include pseudofossil, cast and mold, concretion, and various diagenetic replacement processes. See also: pseudofossil, cast and mold, concretion, taphonomy.