The El Pedregal Formation is a geological formation of Early Aalenian-Early Bajocian (Middle Jurassic) age in the Iberian Basin of W Iberian Peninsula.[1][2][3] This is allocated in the East-Iberian area, that during the Middle Jurassic was part of a Carbonate platform system, influenced by tectonic activity and fault lines, along the Iberian and Catalan Coastal mountain ranges of Spain, with an exposure of up to 500 km.[1][4] This carbonates are allocated on the Chelva Group, that was network of carbonate platforms, with shallow areas forming around elevated blocks created by tectonic forces.[5][6] Deeper marine environments developed between these blocks, which were likely connected to the open ocean. The Internal Castilian Platform was linked to the Iberian Massif, while the El Maestrazgo High separated two marine platforms: the External Castilian and Aragonese.[1][5] Further to the northeast, the Tortosa Platform was bordered by the Tarragona High and Catalan Massif to the north and the El Maestrazgo High to the south. The Beceite Strait acted as a transition zone between the Aragonese and Tortosa platforms.[1][7]
The El Pedregal Formation lithology is dominated by mudstone and wackestone limestones with fine sediments, including microfilaments, echinoderm fragments, and pellets, with less important sequences with interbedded marls, which are indicative of a low-energy marine environment.[8][9] Associated with a shallow carbonate sea, sequences of this formation developed on a confined lagoon, relatively shallow and protected from direct oceanic influence by a volcanoclastic barrier.[9]
This lagoon was developed adjacent or inside an epehemeral volcanic island, shielded from ocean waves by deposits of volcanic materials.[10] Within these calm lagoon settings, carbonate sediments mixed with fine particles that contained plant fossils, preserving evidence of plant-insect interactions, with a low diversity of plants, mainly cycadophytes and ferns.[2][11] Occasionally, storm events would disrupt nearby oyster banks, carrying marine debris, including oysters, into the lagoons, sometimes interspersed with plant remains.[10]
This ephemeral island/islands were situated more than 150 km from the nearest mainland, the Catalan and Iberian Massifs. Following the lagoonal deposits, considered of early Aalenian age, a large regional transgression in the late Aalenian impacted the local platform, connecting the Proto-Atlantic Ocean with the Western Tethys Ocean. Latter in the Bajocian the area evolved into a shallow external marine platform with frequent emersions.[10]
Pelagic/open marine sequences are also common within the formation, including the "Albarracinites beds".[12] At The Masada Toyuela site taphonomic patterns indicate two contrasting sedimentary environments, with taphonic populations dominating in shallow-water settings, marked by reworked and abraded ammonite molds and chambers under slow sediment accumulation punctuated by rapid episodes due to currents and sediment bypassing.[12] Conversely, deeper, sediment-starved areas feature "type 1" taphonic populations, characterized by juvenile, undamaged ammonites within homogeneous molds, typical of condensed deposits from transgressive phases.[12]
A polychaete of the family Dorvilleidae. Unlike the modern counterparts that live in deeper environments, this species is found linked with shallow marine facies
Feeding traces suggest the presence of Coleoptera, Odonata, Lepidoptera and Hemiptera.
Foliar remains with insect interactions are common, including traces of margin feeding, Hole feeding, mining, oviposition, piercing and sucking and surface feeding.[2] Due to be located adjacent to an isolated island, the Camarena locality insect biota likely wasn't too specialized, with generalists more likely to adapt to these environments and inflict similar damage.[2]
Modern equivalents capable of leave similar patterns in extant cycadophytes include caterpillars from genera like Eumaeus (Lycaenidae) and Chilades, along other lepidopteran families, such as Tineidae, Nymphalidae, and Erebidae.[2] Other insects capable of attack cycads include Hemipterans like Aulacaspis yasumatsui or the beetle Brachys cleidecostae (Buprestidae).[2]
Affinities with both Sciadopityaceae and Miroviaceae in the Pinopsida. This pollen's resemblance to extant Sciadopitys suggest that Miroviaceae may be an extinct lineage of Sciadopityaceae-like plants.[13]
Spain
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