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

Comparison with other localities The palynological assemblages from the Maestrazgo Basin documented here are similar to coe- val successions from the Las Parras and Oliete sub-basins [31, 33–35]. Afropollis (Fig 7J), ephe- droid polyplicate pollen (Fig 7O) and several angiosperm taxa such as Dichastopollenites (Fig 9G–9I and 9L) and Cretacaeiporites relate the Spanish assemblages to the palynofloras from North Gondwana (see i.e. [210–214]) and support Iberia as a transitional zone between the flo- ral provinces of NE Gondwana and Laurasia [104]. The Maestrazgo palynological assemblages can also be related to the ones described from the Basque-Cantabrian Basin [31, 87, 104, 132] as both basins share more than 90% of the identified miospore families and a significant num- ber of their respective species. The faunal record, particularly the arthropod assemblages char- acterising the two Iberian areas, reveals a series of common species [162]. Arthropods recorded in the Maestrazgo with a more widespread distribution include Cretevania (Hyme- noptera: Evaniidae) documented in various outcrops across Europe and Asia [215], Serphites (Hymenoptera: Serphitidae) recorded in Europe, Asia, and North America [216] and Micro- phorites (Diptera: Dolichopodidae) found in ambers from France, Lebanon and Myanmar [168]. The coeval miospore assemblages from the Lusitanian Basin exhibit higher angiosperm abundance than the ones described herein [6, 105, 113, 217]. While this difference could likely reflect vegetation with more angiosperms, the higher representation of dinocysts of the Portu-

guese successions suggests the influence of the depositional environments as sedimentary suc- cessions on a passive margin can collect miospores from a larger catchment area. The megafloral record relates the flora from the Maestrazgo to Laurasian assemblages. Tax- onomically similar, low-diversity plant assemblages have been documented from mid-Creta- ceous strata of southwestern and northern France [218–220] and the Czech Republic [83, 172]. These shared characteristics are interesting as they suggest that a few species of angiosperms were thriving in salt-influenced environments and that geographic and climatic barriers did not prevent a widespread distribution across Laurasia. Pathways allowing the dispersal of taxa with such specialised ecological requirements could include coastal fringes surrounding the Tethys. The good representation of Tucanopollis in both NE Gondwana and southern Laurasia suggests that a significant number of halophytic angiosperms used this ‘coastal pathway’ to col- onise new environments. However, more direct, NS trending migration routes following northern and southern Atlantic rift valleys could also be considered to link central Gondwana floras of Gabon and Brazil to Laurasian floras. Despite the numerous similarities existing between floras from Gondwana, mid and north- ern Laurasia, it is probable that the latitudinal migration of flora remained hindered by differ- ences in climate. Floras from locations at equivalent palaeolatitudes, should always present

more compositional and structural similarities than floras from distinct climatic belts. Late Albian–early Cenomanian floras from NW Europe and N America present higher percentages in Gleicheniaceae and Cyathidites but lower diversity in angiosperms than coetaneous floras from southern Europe. Latitudinal effects influenced the composition of the mid-Cretaceous palynological assem- blages from Western Europe and the Atlantic Coastal Plain of USA, since they belonged to the Northern Mid-latitude Warm humid belt (NMW belt) [17, 221]. Although the diversity of taxa was high in the palynological assemblages attributed to the NMW belt, the abundance of mios- pores is different from that of the Maestrazgo Basin (i.e., [90, 112, 222–226]), which was under the influence of the Northern Hot Arid (NHA) belt [17, 188] during the late Albian. More con- cretely, under the influence of the NMW belt, fern spores were generally abundant, showing conspicuous amounts of Gleicheniaceae and Cyathidites, the amounts of Classopollis indicate PLOS ONE Late Albian desert biota from Iberia PLOS ONE | https://doi.org/10.1371/journal.pone.0282178 March 2, 2023 39 / 51