Petrified Arborescent Horsetail-Calamites Arthropithys-
Petrified Arborescent Horsetail-Calamites Arthropithys-
Northern Tocantins Petrified Forest, State of Tocantins, Brazil.
Permian period
6.25″ across.
Horsetails (sphenopsids) are closely related to ferns.