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Paleozoic plant fossil from Australia, known as Glossopteris browniana
because because of its tongue-shaped leaves is the largest genus
of the extinct order of seed ferns known as Glossopteridales. The
Pteridospermatophyta, also called seed ferns, is an extinct gymnosperm
division of the Plantae kingdom. Members of this division were predominant
at the late Devonian and met extinction at the end of the Triassic
period.
The Glossopterids are significant to geological
history as their fossils provided the first evidence of continental
drift. The predominance of glossopterid leaves in Pennsylvanian
to Triassic rocks of Australia, Africa, South America, Antarctica,
and the Indian peninsula lead geologists to conclude that these
continents had once formed Gondwanaland. Moreover, the plants producing
these leaves were ecosystem dominants in the Southern Hemisphere
for most of this period, particularly during the Late Permian.
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