Christian Pott

First record of intact equisetalean strobili from the Wealden (Lower Cretaceous) of the Isle of Wight, southern England


Two excellently preserved small strobili were obtained from a Wealden plant debris bed in the Lower Cretaceous (Barremian) Wessex Formation, south-east of Chilton Chine, on the Isle of Wight, southern England. The strobili are preserved as compressions and show the characteristic morphology of sporangiophore heads of Equisetales. Based on the morphology of the strobili, attribution to a certain species is not warranted. Therefore, the strobili have been left unassigned in the fossil-genus Equisetostachys which is commonly used for isolated strobili of fossil sphenophytes. From their size, shape and constitution, the strobili are interpreted as immature; the absence of preserved sporangia and spores is consequently not unexpected. Affiliation with Equisetum burchardtii might be an option. The strobili represent the first record of any equisetalean or sphenophyte remains from the Wessex Sub-basin of the English Wealden and are thus of considerable importance. The find is especially significant because previously known specimens from the Weald Sub-basin and the German Wealden are confined to subterranean rhizomes, adventitious roots, tubers and bases of aerial shoots, commonly preserved in situ, together with only fragmentary remains of sporangiophore heads from disarticulated strobili. These strobili finds are thus the first intact equisetalean reproductive structures from the Wealden of either England or Germany.

Key words

Equisetostachys, Equisetum burchardtii, Wessex Formation, sphenophyte, horsetail, sporangiophore, strobilus