Glossopteris
Extinct tongue-shaped leaves that revealed the ancient supercontinent Gondwana.
**Glossopteris** (from Greek *glôssa* 'tongue' and *pterís* 'fern') is the most widespread and well-known genus within the extinct Permian seed-plant order Glossopteridales (also called Arberiales, Ottokariales, or Dictyopteridiales). In paleobotany, the name *Glossopteris* is a form genus applied strictly to leaves—specifically those of the glossopterid family Dictyopteridiaceae.
During the Permian, *Glossopteris* species were the dominant trees in middle- to high-latitude lowland areas across the supercontinent Gondwana (the southern part of Pangaea), often growing in swampy environments. These fossils proved crucial for recognizing that South America, Africa, India, Australia, New Zealand, and Antarctica were once connected landmasses.
The *Glossopteris* forest ecosystems vanished during the end-Permian mass extinction about 252 million years ago, triggered by a sharp temperature rise from the Siberian Traps eruptions.
**Description**
The leaves are unmistakable: tongue-shaped (hence the name) with a net-like pattern of veins. They grew either spaced widely along long stems or packed in tight spirals on short shoots. The plants themselves were woody trees and shrubs that bore seeds. Their trunks could reach 80 centimeters (2.6 feet) in diameter, and some likely grew 30 meters (98 feet) tall, with a softwood interior similar to that of modern Araucariaceae conifers.
Seeds developed on one side of branched or fused structures, while pollen-bearing microsporangia clustered at the tips of slender filaments. Both seed- and pollen-bearing organs were partially fused to the leaves, or possibly positioned in the leaf axils. The nature of the flattened seed-bearing structures has long been debated: some researchers see them as megasporophylls (fertile leaves), others as flattened, seed-bearing axillary axes (cladodes). It remains unclear whether glossopterids were monoecious or dioecious, though the discovery of layers containing only pollen-bearing leaves—and no ovules—suggests at least some species were dioecious.
**Distribution**
More than 70 fossil species have been identified in India alone, with additional ones from South America, Australia, Africa, Madagascar, and Antarctica.
Quick Facts
- Taxon
- Glossopteris
Facts from the source article.
Lore & Background
The leaves of Glossopteris are characterized by their distinctive tongue shape and reticulate venation. Leaves were either widely spaced on long stems or densely helically arranged on short shoots. Glossopteris-bearing plants grew as woody, seed-bearing trees and shrubs, with trunks up to 80 cm in diameter and some likely reaching 30 m in height. They had a softwood interior resembling Araucariaceae conifers. Seeds were borne on one side of variably branched or fused structures, and microsporangia containing pollen were borne in clusters at the tips of slender filaments. Both seed- and pollen-bearing organs were partially fused to the leaves or possibly positioned in the leaf axils. The homologies of the flattened seed-bearing structures remain controversial, with some arguing they represent megasporophylls and others interpreting them as flattened, seed-bearing axillary axes. It is unclear whether glossopterids were monoecious or dioecious; the fact that only pollen organ bearing leaves and not ovules were found in some layers suggests at least some species were dioecious.
Reader's Guide
Glossopteris is significant as the dominant tree of Permian Gondwana and as a key fossil in recognizing the former connection of southern continents. Its distribution across South America, Africa, India, Australia, New Zealand, and Antarctica led Eduard Suess, among others, to propose that these landmasses were once amalgamated into a single supercontinent—Pangaea. Glossopteris forests became extinct as part of the end-Permian mass extinction event approximately 252 million years ago, caused by an abrupt rise in temperatures from the eruption of Siberian Traps. The genus is restricted to the Permian; putative Triassic records are stratigraphically ambiguous or based on misidentifications. Glossopteris was an important contributor to vast Permian coal deposits of the Southern Hemisphere. Its leaves ranged from about 2 cm to over 30 cm in length. The plants are interpreted to have grown in very wet soil conditions, similar to the modern bald cypress. They are assumed to have been deciduous, though an isotopic study found that Antarctic Glossopteris forests were mixed evergreen-deciduous. Glossopteris trees likely were wind pollinated.
Did You Know?
- More than 70 fossil species of Glossopteris have been recognized in India alone.
- The name Glossopteris comes from Ancient Greek γλῶσσα (tongue) and πτερίς (fern).
- Glossopteris fossils were critical in recognizing former connections between South America, Africa, India, Australia, New Zealand, and Antarctica.
More in Fossils of Antarctica 1-24
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