Cryptospores

Cryptospores are fossilised primitive plant spores that first appear in the fossil record during the late Ordovician to early Silurian period.

Occurrence
Cryptospores are generally found in non-marine rocks and decrease in abundance with distance offshore. This suggests that any cryptospores found in the marine environment were transported there by the wind from the land, rather than originating from the marine environment.

Wall Ultrastructure
The lignified walls of cryptospores consist of many lamellae (thin sheets). Liverworts, thought to be the most primitive land plants, also have this spore wall morphology.

Other information
Recently, fossils of plant sporangia have been found in Oman with cryptospores showing concentric lamellae in their walls, similar to liverworts.