On the Origin of Lycopsids
published: Sep 22, 2009
Almost all authors agree that zosterophylls and lycopsids have the same origin. However, both must have diverged from each other at a very early stage. They have mostly been considered sister groups forming two clades. Only the position of the Drepanophycales remains controversial and is discussed here. There are two possibilities, either they belong to the zosterophylls as the highest member of that lineage, or they represent an intermediate stage between zosterophylls and lycopsids. A third clade, the multisporangiate Barrandeinales that has been neglected until now, is introduced.