maggot stone from Kleinnaundorf near Freital, detail
Fertile pinnules of the tree fern Scolecopteris/Psaronius: one
pinnule in top view
with faintly visible veining (above), others as in-plane and cross sections.
The row
of pinnules constitutes a pinna whose axis is hidden beneath the cut face.
Pinnule width up to 2 mm.