Evaluation of different strategies for in-situ preservation of dinosaur footprints at the Sezze ichnosite (Latium, central Italy)

Geoheritage represents an essential segment of natural heritage, encompassing a range of geological resources with scientific, cultural and educational significance. Among these, ichnosites, which preserve footprints and traces left by organisms during their lifetime, are of particular importance for understanding the evolutionary and paleoenvironmental history of extinct terrestrial tetrapods (García-Ortiz et al., 2014). Sezze ichnosite (about 70 km south of Rome) is characterised by over 230 dinosaur footprints preserved on three distinct bedding surfaces in the abandoned Petrianni Quarry, representing to date the most extensive dinosaur tracksite in central Italy (Nicosia et al., 2007; Petti et al., 2020; Antonelli et al., 2023). The track bearing surfaces are continuously affected by exogenous agents and the theropod and sauropod footprints are significantly degraded and at serious risk of being obliterated due to ongoing natural processes. To develop a long-term strategy for in-situ preservation, various approaches were tested on mock-ups simulating dinosaur footprints to evaluate their effectiveness. The consolidants used included two commercial products (Siox5 RE50 and NanoEstel) and two experimental formulations (TEOS with chitosan nanoparticles and a chitosanbased solution). Additionally, a bioconsolidation process was tested using carbonatogenic bacteria isolated from the ichnosite and identified as Lysinibacillus fusiformis strains. To assess the durability of consolidant treatments to acid rain exposure, the samples were partially immersed for a month in a 10-4 M sulfuric acid solution. The mock-ups were analysed using optical microscopy, scanning electron microscopy, peeling test and colorimetry. A digital comparison of mock-up surfaces before treatments, after consolidant application and after artificial ageing was performed using high-detail 3D models produced by Structure from Motion (SfM) photogrammetry. The results show differences in the adhesion and durability of the protective layers formed on sample surfaces by each consolidant, allowing the evaluation of their suitability for in-situ application. Antonelli M. et al. (2023) - Inferred oviraptorosaur footprints in the Apenninic Carbonate Platform: New tools for the identification of trackmakers from the Sezze ichnosite (lower-middle Cenomanian; central Italy). Cretaceous Research, 141, 105362, https://doi.org/10.1016/j.cretres.2022.105362. García-Ortiz E. et al. (2014) - Concepts and terminology for the risk of degradation of geological heritage sites: fragility and natural vulnerability, a case study. Proceedings of the Geologists’ Association, 125(4), 463-479, https://doi. org/10.1016/j.pgeola.2014.06.003. Nicosia U. et al. (2007) - Dinosaur Tracks as Paleogeographic Constraints: New Scenarios for the Cretaceous Geography of the Periadriatic Region. Ichnos 14, 69-90, https://doi.org/10.1080/10420940601006859. Petti F.M. et al. (2020) - Cretaceous tetrapod tracks from Italy: a treasure trove of exceptional biodiversity. Journal of Mediterranean Earth Sciences, 12, 167-191, https://dx.doi.org/10.3304/jmes.2020.16873.