Detailed Asterophyllites and Callipteridium Plant Fossils Association

Description: This is a fine association plaque of two dissimilar plants from the Carboniferous of Spain. The delicate specimen in the upper right is Asterophyllites, a member of the Calamitales, a member of the Sphenophytes. Whorls of small leaflets are arranged concentrically around a thin stem. These were indicative of humid to wet habitats such as along rivers and lake shores. The only living example of the sphenophytes is the horsetail Equisetum. The other specimens found on both sides of the piece are Callipteridium gigas, a relatively rare seed fern. Pteridosperms or seed ferns are a group of extinct plants with mostly fern-like foliage but with real seeds. They are mostly reconstructed as small trees but also forms with a climbing growth habit gave been found. Some forms, notably those called the Medullosales, have large fronds which could be up several meters long. Several groups can be distinguished within the Pteridosperms. The Pteridosperms evolved in the latest Devonian, and became common in the Carboniferous. The Medullosales took over the leading role during the Westphalian and persisted into the Permian.