Caytoniales in Early Jurassic floras from Antarctica
The Caytoniales are represented in the Early Jurassic floras from Hope Bay and Botany Bay, Antarctica, as completeleaves and detached leaflets (Sagenopteris) together with microsporophylls (Caytonanthus). Systematic sampling at Botany Bay has shown that they occur only in a one metre interval within the sedimentary sequence. Such intimate association of leaves and microsporophylls has been recorded previously in only a few Northern Hemisphere floras and has been used as evidence to assign them to the same order (the Caytoniales). Caytonanthus is described here for the first time from a gondwanan flora and its close association with Sagenopteris provides further evidence that they are related biologically. The leaflets show a large range in morphology, possessing entire, undulating or lobed margins, but are all assignable to the same species. Such a range in leaflet shape has not been documented previously for a species of Sagenopteris. It can be explained by considering possible variations in the original habitat of “the Caytonia plant”.