A new macroflora from the Middle Jurassic (Bathonian) of NW Jordan and its palaeoenvironmental significance

摘要

This work provides a first overview on a hitherto undescribed macroflora from the Middle Jurassic (Bathonian) of NW Jordan. The allochthonous plant remains occur as impressions and compressions in (marginally) marine sandstones and siltstones. The flora consists of sphenophytes (Equisetum cf. columnare), two (or three) taxa belonging to ferns and different morphotypes of pinnately leaved gymnosperms. Most of these are likely belonging to the Bennettitalean genera Zamites (2 morphotypes), Otozamites (2 morphotypes) and Ptilophyllum (3 morphotypes). Besides these remains, small pieces of amber, with diameters <10 mm, have been discovered dispersed in plant bearing siltstones. A comparison with other Jurassic floras from the Middle East region shows that its taxonomic composition can be best compared to the macroflora from the Aalenian Early Bajocian Imran Formation of Makhtesh Ramon in the Negev (Southern Israel). However, so far we found no evidence of (scale-leaved) conifers in Jordan, whereas all so far known Jurassic floras from the Negev constantly include a diverse and often abundant component of such conifers. The new flora can tentatively be classified as a fern-bennettitalean community (forming a kind of 'savannah'-like vegetation), typical for tidal flats of this period, together with abundant sphenophytes, probably originating from riparian/deltaic habitats.