Two fossilized swamps containing in situ Sphenophyta stems, rhizomes, and root systems from the Middle Jurassic Hojedk Formation, Kerman area (Iran)

Sphenophytes often occur in wet environments; examples include the many extant equisetaleans that grow along streams, lake banks, and marshes. In the northern part of Kerman Province in Central Iran, in sandstone beds of the Middle Jurassic Hojedk Formation, there are two wetland sites, Swamp 1 and Swamp 2, separated by ~160 m along the sequence. Large numbers of in situ stems of sphenophytes were recorded there. They are preserved as casts, with imprints of the external cortex and/or vascular bundles of the internal cylinder. The stems belonged to one genus, Neocalamites , represented by three morphotypes. In Swamp 1, all the stems are large, ~120–220 mm in diameter, and of arborescent habit, while in Swamp 2, they do not exceed 20 mm in diameter. Swamp 2 contains two stem morphotypes that significantly differ in the number of vascular bundle traces. Such a type of Sphenophyta stem found in situ has not been reported from other regions of Iran or other parts of the world. The deposits of both swamps indicate a meandering river system. The observed Sphenophyta colonies and trace fossils found in the same bed may indicate undisturbed life conditions occurring after cessation of environmental stress.