Biodiversity of ecosystems in an arid setting: The late Albian plant communities and associated biota from eastern Iberia

that it was a sub-dominant pollen type, bisaccate and inaperturate conifer pollen reaches con- spicuous values, and angiosperm pollen exhibits high diversity and significant abundances (i.e., abundances of more than 30% of angiosperm pollen, and a diversity of around 47 taxa in Zone II of the Potomac Group [112]). Additionally, the late Albian–early Cenomanian palynofloras from the Northern High-lati- tude Temperate Humid (NHT) belt are characterised by a high diversity of dinocysts, trilete spores and angiosperms (see i.e., [111, 227–229]). For example, the coeval existence of quite different plant communities from those described in eastern Iberia can be regarded if compar- ing the late Albian floras from Peace River Area (Alberta, Canada) [229]. These floras are char- acterised by scarce Classopollis, high amounts of bisaccate pollen grains of the genera Alisporites and Vitreisporites, trilete spores such as Cingutriletes, Gleicheniidites, and Stereispor- ites, as well as conspicuous values of tricolpate angiosperm species (Cupuliferoidaepollenites parvulus, Tricolpites sagax, T. vulgaris). Conclusions The palaeobotanical study of three sections from the Utrillas Group in the Maestrazgo Basin (Iberian Ranges, eastern Spain) reveals the existence of ancient conifer woodlands and fern/ angiosperm communities that thrived in the mid-Cretaceous Iberian Desert System. Four veg- etation types have been inferred: the first one is characterised by arid woodlands of Cheirolepi- diaceae-Cupressaceae, the second is related to coastal settings with Araucariaceae, the third is

related to salt marshes, and the fourth represents local fern and angiosperm communities linked to wet interdunes (oases) and wetlands. The existence of ponded areas linked to wet interdunes is interpreted based on the high percentages of fern spores, the common occur- rence of angiosperm pollen and the lack of marine palynomorphs. The presence of spikes of Tucanopollis spp. and “Liliacidites” minutus in the CA section might be related to the relevant role of the angiosperms in the colonisation of xeric and disturbed habitats and the ecological successions in arid settings. The biostratigraphic markers recorded in the studied sections confirm a late Albian age, except for the uppermost levels of the Cortes de Arenoso section (La Hoya amber outcrop), in which an early Cenomanian age might be inferred based on the occurrence of Echinipollis cen- omanensis, Polypodiisporonites cenomanianus and Senectotetradites grossus. Although the late Albian palynoflora from the Maestrazgo Basin was influenced by the palaeoclimatic conditions that prevailed in the Northern Hot Arid belt, the studied assemblages can generally be related to others from Europe and North America. However, the presence of pollen grains of the gen- era Afropollis, Equisetosporites, Gnetaceapollenites, Steevesipollenites, Dichastopollenites and Cretacaeiporites indicates that Iberia was a transitional area between the Northern Gondwanan and the Southern Laurasian provinces. In this sense, the studied macrofloristic assemblages from the Maestrazgo Basin show similarities to others from the European Laurasia.

Supporting information S1 Appendix. Absolute abundances of palynomorphs in the studied sections from the Maestrazgo Basin. (XLSX) S2 Appendix. List of the identified taxa ordered according their botanical and zoological identification, and the alphabetic citation of the taxonomic authorities. (DOC) PLOS ONE Late Albian desert biota from Iberia PLOS ONE | https://doi.org/10.1371/journal.pone.0282178 March 2, 2023 40 / 51