Genus Callixylon Zalessky (Archaeopteridophyta): Main criteria for distinguishing its species and revision of its species composition

摘要

A new revision of the genus Callixylon Zalessky, which dominated in the Late Devonian all over the world, is presented. The most significant anatomical features for distinguishing its species are revealed, which is very important for establishing the species diversity in the first forests in the Earth's history.