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

Deserts are stressful environments where the living beings must acquire different strategies to survive due to the water stress conditions. From the late Albian to the early Cenomanian, the northern and eastern parts of Iberia were the location of the desert system represented by deposits assigned to the Utrillas Group, which bear abundant amber with numerous bioinclusions, including diverse arthropods and vertebrate remains. In the Maestrazgo Basin (E Spain), the late Albian to early Cenomanian sedimentary succession represents the most distal part of the desert system (fore-erg) that was characterised by an alternation of aeolian and shallow marine sedimentary environments in the proximity of the Western Tethys palaeo-coast, with rare to frequent dinoflagellate cysts. The terrestrial ecosystems from this area were biodiverse, and comprised plant communities whose fossils are associated with sedimentological indicators of aridity. The palynoflora dominated by wind-transported conifer pollen is interpreted to reflect various types of xerophytic woodlands from the hinterlands and the coastal settings. Therefore, fern and angiosperm communities abundantly grew in wet interdunes and coastal wetlands (temporary to semi-permanent freshwater/salt marshes and water bodies). In addition, the occurrence of low-diversity megafloral assemblages reflects the existence of coastal salt-influenced settings. The palaeobotanical study carried out in this paper which is an integrative work on palynology and palaeobotany, does not only allow the reconstruction of the vegetation that developed in the mid-Cretaceous fore-erg from the eastern Iberia, in addition, provides new biostratigraphic and palaeogeographic data considering the context of angiosperm radiation as well as the biota inferred in the amber-bearing outcrops of San Just, Arroyo de la Pascueta and La Hoya (within Cortes de Arenoso succesion). Importantly, the studied assemblages include Afropollis, Dichastopollenites, Cretacaeiporites together with pollen produced by Ephedraceae (known for its tolerance to arid conditions). The presence of these pollen grains, typical for northern Gondwana, associates the Iberian ecosystems with those characterising the mentioned region.

Mapping Early Pleistocene environments and the availability of plant food as a potential driver of early Homo presence in the Guadix-Baza Basin (Spain).

The Guadix-Baza Basin, in SE Spain, harbors hominin fossils and lithic artifacts dated to ca. 1.4-1.3 Ma, representing the first hominin habitat in the Iberian Peninsula and possibly in Western Europe. Recent palynological studies have described a high diversity of plant taxa and biomes existing in the basin at the time of hominin presence. However, the relationship between these hominins and their environment has not been fully explored. Two novel methodologies are developed. The first method maps the distribution of the Early Pleistocene vegetation units based on paleobotanical and paleogeographic data. The second method assesses the availability of edible plant parts using a combination of Early Pleistocene and modern taxa lists. The resulting vegetation maps reveal a great diversity of vegetation types. During dry (glacial) periods, the vegetation of the basin was represented mostly by steppes, with the appearance of forested vegetation only in the mountainous regions. During humid (interglacial) periods, Mediterranean woodlands represented the dominant vegetation, accompanied by deciduous and conifer forests in the areas of higher altitude. The lake system present in the basin also allowed for the presence of marshland vegetation. The assessment of the availability of edible plant parts reveals that early Homo could have found a high number of resources in marshland and riparian environments throughout the year. Mediterranean woodlands and deciduous forests also provided numerous edible plant parts. During dry periods, the availability of plant resources decreased heavily, but the prevalence of marshland and riparian vegetation and of forested vegetation in the areas of higher altitude could have sustained hominin communities during harsher climatic periods. However, the disappearance of the lake system and an increase of aridity after the Mid-Pleistocene Transition and during the Middle Pleistocene probably led to an impoverishment of plant resources available to early Homo in the Guadix-Baza Basin.