Taxonomic resolution of the Triassic–Jurassic sporomorph record in East Greenland

Abstract. Sporomorphs (pollen and spores) provide valuable information about vegetation history over a range of temporal and spatial scales. However, sporomorphs can be morphologically invariant among species within genera, and among genera within certain families. In some cases, the parent plant of a sporomorph is unknown. These factors blur the relationship between sporomorph assemblages and the source vegetation, and reduce the taxonomic precision of vegetation reconstructions based on sporomorphs. This study investigates the taxonomic precision with which sporomorphs record vegetation across the Triassic–Jurassic transition (Tr–J) at Astartekløft, East Greenland. Results indicate that reconstructions of Tr–J vegetation at Astartekløft based on sporomorphs are hampered by considerable taxonomic imprecision. Something is known of the botanical affinity of almost all sporomorphs at Astartekløft at the class level, but just 50% of sporomorph taxa have a known botanical affinity at the family level. Additionally, ~23% of all sporomorph taxa at Astartekløft have affinities to more than one parent plant class, and ~36% of sporomorph taxa have affinities to more than one parent plant family. This taxonomic imprecision should be accounted for when interpreting percentage diagrams of sporomorph taxa across the Tr–J.