What evidence suggests that gnetophytes existed as far back as the Permian Period?

The evidence suggesting that gnetophytes existed as far back as the Permian Period is based primarily on the fossil record of pollen grains.12

Specifically, paleobotanists have identified pollen grains that are similar to those produced by the extant genera Ephedra and Welwitschia within Permian-aged deposits. While the broader fossil record for the division Gnetophyta remains obscure and the origin of the group is not entirely clear, these pollen findings serve as the primary indicator for their presence during that time. Later, more definitive physical remains of possible gnetophytan plants—such as leafy shoots and microstrobili—have been recovered from the Early and Upper Cretaceous periods, which exhibit features consistent with the division.12