Palynology of Bathonian macroflora-bearing beds from NW-Jordan – expanding a rare ‘peephole’ into Middle Jurassic palaeotropical vegetation

Abstract

Abstract A diverse and well-preserved sporomorph assemblage was recovered from the Middle Jurassic (Bathonian) marine Arda Formation in Jordan. The recorded palynomorphs originated from macroflora-rich layers that primarily represent a bennettitalean-fern community. This finding closely aligns with palynological results, which indicate a dominance of fern spores, accompanied by some gymnosperm pollen. The latter group includes taxa such as Cycadophytes and Exesipollenites dyads, affiliated with Bennettitales. Additionally, conifers in the studied assemblages, including Araucariaceae, are represented by a diverse assemblage of Callialasporites , along with Araucariacites pollen taxa. Cheirolepidiaceae is represented by Classopollis , along with Cupressaceae ( Cupressacites ), as well as a less frequent bisaccate pollen taxa. Despite the limited number of samples, this palynological data significantly enhances our understanding of the Middle Jurassic vegetation and its palaeoenvironments in Jordan, one of the very few palaeotropical floras from that time period for which both macro- and microflora are known. The dominance of terrestrial palynomorphs and the scarcity of marine forms, along with abundant macrofloral elements, indicate a strong terrestrial influence on the plant-bearing layer. This suggests a possible mixing of plants from various habitats, potentially transported by an ancient river, or that these plant-bearing layers represent a temporary sea-level fall or regression phase.