Sprecher
Beschreibung
Extant Banksia, an iconic Australian genus, have a series of xeromorphic traits (sclerophyllous leaves and bark; sunken stomata; typically revolute or recurved leaf margins) and are primarily serotinous. Because they are well-adapted to the dry, fire-prone environments of modern Australia, their presence in the fossil record is often interpreted as an indication of seasonality or aridity (Hill, 1998; Carpenter et al., 2014). These interpretations often conflict with other lines of evidence, including sedimentology, for their occurrence in wet palaeoenvironments (Korasidis et al., 2019) or even other plants in the same assemblage (McCurry et al., 2022). This study investigates three Banksia species (B. angusta, B. cooksoniae, B. laevis) that are found co-occurring in a thin stratum within the large Middle Miocene (~15 my) Yallourn Coal Seam; part of the Gippsland Basin in Victoria, Australia. This layer has been designated the “Banksia layer,” because of the predominance of Banksia macrofossils. These three Banksia have distinct morphological features, indicating different life strategies and adaptations to the low-nutrient pedogenic conditions and frequent fires that plagued the emergent marsh ecosystem they inhabited. Seven infructescences recovered from Yallourn, have been CT-scanned, and related to their respective species. These three species are redescribed using their leaves, cuticles, and infructescences. By conducting a morphological comparison with extant Banksia, the nearest living relatives are identified for the three Yallourn Banksia, and their life strategies compared and evaluated from a palaeoenvironmental perspective. Having these species co-occurring in a water-logged, peatland environment invites further investigation of how Banksia evolved in Australia.