The study of cuticular and epidermal features in fossil plant impressions using silicone replicas for scanning electron microscopy

Abstract

The study of epidermal and cuticular features is crucial in palaeobotanical investigations. In fossil plant impressions organic material is not preserved and cuticular data is commonly believed to be missing. This work describes a redefined version of the silicone cast technique for SEM examination known since almost 40 years, but unfortunately rarely used in routine palaeobotanical studies. The use of silicone (vinylpolysiloxane) instead latex casts offers significant advantages such as easier handling, higher reproduction of surface details, and elimination of electrostatic charge accumulation. The results indicate that silicone represents an improvement over latex. With this technique excellent results can be achieved, possibly making visible several plant surface structures, including epidermal cells, stomata, papillae, trichomes and striations on the rachis. Moreover, this technique demonstrates that impression fossils can provide similar useful data like those seen in compressed fossils. The effectiveness of this technique is demonstrated with several examples of fossil plants from the Triassic Madygen Lagerstätte. The application of this simple, non-destructive and extremely effective technique provides significant biological information on the cuticular and epidermal features in fossil plant impressions despite the absence of cuticles, to resolve taxonomic problems as well as to infer diverse ecological adaptations. © Palaeontological Association August 2012.