Seed ferns from Yorkshire

Click on the photos for more information..
The seed ferns carried on for a long time after the major extinction at the end of the Permian, though in modest numbers. The last ones died out in the Cretaceous. Seed ferns often had a thick cuticle, which has been preserved on the fossils as a thick coaly layer.
Several groups of seed ferns have been discovered in the Yorkshire area. Most famous are the Caytoniales (named after Cayton Bay). The reason of this celebrity is that for a long time it has been thought that they were ancestors of the modern flowering plants (the angiosperms). An indication for this idea was the reticulate venation of the leaves. Since then this has turned out not to be the case.
Sagenopteris phillipsiiThe leaves of the plants from this group are assigned to the genus Sagenopteris. A leaf is composed of (mostly) four leaflets sitting on top of a petiole. A complete leaf is very rare but the detached leaflets are rather common. The elongated form and the reticulate venation make identification easy. In Cayton Bay the species Sagenopteris philipsii is the most common one.
We have also found an aberrant leaf with one circular leaf instead of four small elongated leaflets. Click on the photo on the left.

Rhaphidopteris simpsoniiIn Cayton Bay also the species Sagenopteris colpodes with small leaflets occurs, but this one is much more rare. In Hasty Bank, however, this species is abundant, but in a variety with larger leaves.
Of these plants male and female fructifications have been found, but we didn't have the pleasure. The 'fruits' are round and about 4 mm in diameter. They are filled with a couple of seeds, measuring about 1 mm.

A rare find was a rather complete plant of the species Rhaphidopteris williamsonii, which until recently was called Stenopteris williamsonii. This plant has leaflets, divided in long, narrow parts. Mostly detached leaflets are found. Click on the photo on the right.