Extinct Seed Plants

Pterophyllum jaegeri. Bennettitales. Lunz, Lower Austria. 220 million years.

The fossil plants of Lunz are unique in their wealth, their diversity and their outstanding state of preservation.

TO THE LAST CELL
The swamp forests of Lunz came into being at a time of a global dying off of reefs. The probable cause was a huge monsoon system, which developed along the coasts of the Tethys ocean. Torrential rains washed nutrients into the oceans, where algae bloom and slime threatened the marine ecosystem and killed off numerous marine organisms. By contrast, the plants of the swamp forests in the coastal regions flourished.
Besides the bennettitales that produced these feathery fronds, cycadaceae and gingko trees also flourished in these swamps. Between them ferns and tree ferns, horsetails and lycopodiaceae grew vigorously. The oxygen-poor environment of the swamp areas has preserved incredible details in the fossils – for example, the cuticula of many leaves. This thin wax layer is deposited on the surface of the leaves, giving mouldings of every cell and stomate. As the plants also absorb carbon dioxide (CO2) through the stomata, the density of stomata provides an indication of the CO2 content of the atmosphere in the early Earth.
The lagerstätte in Lunz was discovered over 160 years ago. The bennettitale feathery fronds were purchased by the museum in 1887. Bennettitales – relatives of today’s palm ferns – are believed to be typical of the Mesozoic period. Their blooms were already monoecious, and probably also attracted insects for pollination. The seed pods, surrounded by protective scales, are reminiscent of angiospermous flowering plants, although these only developed considerably later.