A gymnosperm affinity for Ricciisporites tuberculatus Lundblad: implications for vegetation and environmental reconstructions in the Late Triassic

作者：Kurschner Wolfram M^*; Mander Luke; McElwain Jennifer C

来源：Palaeobiodiversity and Palaeoenvironments, 2014, 94(2): 295-305.

DOI：10.1007/s12549-014-0163-y

• Triassic
• Rhaetian
• Palynology
• In situ pollen and spores
• Herbaceous gymnosperm
• Classopollis

Ricciisporites tuberculatus Lundblad is a prominently sculptured palynomorph that is dispersed at maturity as tetrads. It has a wide geographic distribution and reaches a stratigraphically important acme in the Norian and Rhaetian of Europe. As it has not yet been found in situ in a fossilized reproductive structure, its botanical affinity is poorly understood. Recent work on the morphology and ultrastructure of R. tuberculatus favours an affinity with gymnosperms rather than spore plants. In the present contribution, we re-evaluate Triassic-Jurassic (Tr-J) palynological records and discuss the consequences of a gymnosperm affinity for R. tuberculatus for Late Triassic vegetation reconstruction, as well as inferred palaeoecological interpretations. At a Tr-J boundary locality in East Greenland, the relative abundance of R. tuberculatus through time is similar to the Bennettitales Anomozamites and Pterophyllum. We suggest that R. tuberculatus may have been produced by a gymnosperm characterised by an herbaceous ruderal life habit. The poor preservation potential of the vegetative structures of such a plant may explain why R. tuberculatus has not yet been found in situ in a fossil reproductive structure. Moreover, principal component analysis of Late Triassic palynological records show that the vectors of R. tuberculatus and the common pollen type Classopollis plot in opposite directions. We suggest that the parent plants of R. tuberculatus and Classopollis (the Cheirolepidiaceae) may have had different ecological and/or climatological preferences.

• 出版日期2014-6