The first record of Dicroidium from the Triassic palaeotropics based on dispersed cuticles from the Anisian Mukheiris Formation of Jordan

Abstract

A new fossil meso-flora consisting of dispersed cuticles has been discovered within the Upper Member of the Middle Triassic (late Anisian) Mukheiris Formation at the eastern rim of the Dead Sea in Jordan. The assemblage consists of a number of different morpho-types of cuticles which can all be assigned to gymnosperms. Cuticles which can be identified as the corystospermalean taxon Dicroidium are fairly abundant and clearly dominate the assemblage, whereas cuticles assignable to other gymnosperms are rather rare. As so far all Triassic records of Dicroidium come from localities at palaeolatitudes above 35°S, these cuticles represent the first record of this genus within the Triassic palaeotropics. Our analysis of this meso-flora suggests that during the late Anisian, as in other regions worldwide, a gymnosperm component of the terrestrial vegetation on the Arabian Peninsula was present. Compared to the palynoflora, which yielded various types of conifer pollen, and pollen of other gymnosperm groups, as well as abundant spores of ferns and lycophytes, the meso-flora is so far lacking a number of plant groups which were present in the source vegetation. It is likely that the differences can be explained by taphonomical biases. The data from cuticles and palynology together prove that either regional terrestrial ecosystems had already recovered, at least to some extent, from the devastating effects of the end-Permian ecological crisis or that these effects were less devastating, at least with regard to vegetation, than assumed by previous studies.