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These are the permineralized seeds of a medullosan seed fern. These particular fossils come from the Francis Creek Shale in Illinois, and are more than 300 million years old.  Glossopteris, an important plant in widespread Permian floras of the Southern Hemisphere, was a seed plant. Glossopteris, the genus from which the group gets its name, is also the largest and best-known member of the Glossopteridales. More than 70 species of this genus have been recognized in India alone, with additional species from South America, Australia, Africa, and Antarctica. Only a few fossils from the northern hemisphere have been considered as members of this group, but these are not identified with great certainty. Our best guess is that they were large shrubs or small trees, perhaps a bit like a magnolia or ginkgo. There is at least some evidence that, like Ginkgo, glossopterids had a stem system of both long and short shoots. In Ginkgo, it is the short shoots that produce most of the leaves, and that bear the seeds and pollen structures. This may also have been the case for the glossopterids, but no one is certain.
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Plants 
