A petrified cycad trunk from the Late Cretaceous of the Larsen Basin, Antarctica

Lachman Crags Member of the Santa Marta Formation, Marambio Group, James Ro ss Island, Antarctica. The petrified trunk comprises a thick pith containin g thin and thick walled parenchymous cells, vascular traces surrounded by a thin layer of loose secondary wood. Medullary bundles arise inside the woo d zone and pass outwards through multiseriate medullary rays. The trunk ana tomy indicates assignment to the Cycadales, and the presence of medullary b undles indicates the affinities with a clade comprising Lepidoramia, Macroz amia, and Encephalartos. This clade is presently confined to Australia and Africa, but fossil representatives extend the geographic range to India, So uth America and now Antarctica.