Feeding behavior of giant trilobites from the Penha Garcia Ichnological Park (UNESCO Naturtejo Global Geopark, Portugal)
1 UNESCO Naturtejo Global Geopark‐Geology Office of the Municipality of Idanha‐a‐Nova, Centro Cultural Raiano, Idanha‐a‐Nova, Portugal 2 Instituto D. Luiz, University of Lisbon, Lisbon, Portugal 3 DISTAV, University of Genova, Genoa, Italy 4 Department of Earth Sciences, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran 5 Geo‐environment and Geoheritage Group, Geology Department, Faculty of Sciences, Ibn Zohr University, Agadir, Morocco 6 “Monachus” Group of Scientific Research and Ecological Education, Constanta, Romania The Ichnological Park of Penha Garcia located in central east Portugal, near the border with Extremadura (Spain), is a reference geosite for the Naturtejo UNESCO Global Geopark. The extremely abundant and well‐preserved trace fossil record is characteristic of the Armorican Quartzite facies across northwestern Gondwana which are composed of mixed‐influenced asymmetrical deltaic deposits from the southern margin of the Rheic Ocean, developed during its drifting stage. The protected section in the Ponsul river gorge covers an area of 1 km2 and its paleontological record dates from Lower‐to‐Middle Ordovician (Floian–Darriwilian). It was first studied in the 1850s (Baucon et al. 2012), becoming a worldwide reference for understanding the intrastratal pres‐ ervation and foraging ethology of the ichnogenus Cruziana, the archetypical form of the Cruziana Ichnofacies (Goldring 1985; Neto de Carvalho 2006; Seilacher 2007). The sedi‐ mentary succession is over 300 m thick. Detailed analysis of the geometry and internal architecture of the depositional phases along the depositional strike showed that the deposi‐ tion of the Penha Garcia Formation likely took place under an increase in the rate of accommodation, due to long‐term relative sea‐level rise and high subsidence rates, coupled with an increase in sediment supply, which could have been locally amplified by compaction of the prodelta‐related pelitic beds. The highest bioturbation intensities and ichnodiversity occur in storm‐dominated delta front facies associations. So far, 21 ichnogenera and 36 ichnospecies have been identified at Penha Garcia. These ichnotaxa reflect a wide spectrum of behaviors, ascribed to trilobites, bivalves, phyllocarid crustaceans and other endobenthic arthropods, anemones, protobranch bivalves, sessile and vagile worms (Neto de Carvalho et al. 2014). Several aspects make Penha Garcia a reference site of ichnological international importance: (1) the abundance of trace fossils of the Cruziana rugosa group, represented by thousands of trace fossils disrupting over 100