Archaeocalamitaceae

Archaeocalamitaceae is a family of extinct sphenopsids related to horsetails. Archaeocalamite fossils have been found in Siberia, Poland, and Brazil. The fossils date to the Middle Devonian-Carboniferous, lower Carboniferous (Dinantian), and the lower Permian respectively. Given the distance of the fossil discoveries, archaeocalamites may have had a subcosmopolitan distribution.

Taxonomy
Possible relationships archaeocalamites has with other sphenopids is shown below.