Lyginopteridales

Diplopteridium holdenii

Crossotheca nodule

Mariopteris sauveurii

Lyginopteridales is an extinct order of seed ferns that were prominent during the late Paleozoic era, particularly in the Carboniferous and Permian periods. These plants are significant in the study of plant evolution as they represent an early group of seed plants, showcasing the transition from spore-bearing plants to those that reproduce via seeds. Lyginopteridales are part of a larger group known as the Pteridospermatophyta or seed ferns, which are not true ferns but rather a grade of several lineages of extinct seed-bearing plants that superficially resemble ferns.

Characteristics

Lyginopteridales were characterized by their complex leaves, which were often large and divided into segments, resembling the fronds of modern ferns. These leaves are known as fronds. The reproductive organs of Lyginopteridales were seeds, which were often encased in a hard outer layer, and these seeds were borne on different parts of the plant, including the fronds in some species. Unlike modern ferns, which reproduce via spores, the seed-bearing nature of Lyginopteridales represents a significant evolutionary advancement.

Evolution and Significance

The Lyginopteridales are considered crucial in understanding the evolution of seed plants. They provide evidence of the early stages of seed plant evolution, where features typical of both ferns and seed plants coexisted. This group helps scientists understand how plants transitioned from spore-bearing reproduction to seed-based reproduction, a major evolutionary step that allowed plants to colonize new environments and eventually dominate terrestrial ecosystems.

Fossil Record

Fossils of Lyginopteridales have been found in various parts of the world, indicating that they were widespread during the Paleozoic. These fossils include both vegetative and reproductive parts, allowing scientists to reconstruct their appearance and understand their life cycle. The fossil record shows that Lyginopteridales were diverse, with several genera and species described.

Decline and Extinction

The decline of the Lyginopteridales began towards the end of the Paleozoic era, with the group becoming extinct by the end of the Permian period. This extinction is part of a larger pattern of plant turnover at the end of the Paleozoic, which saw the decline of many primitive plant groups and the rise of more modern groups, such as the gymnosperms and later the angiosperms. The reasons for the decline and extinction of Lyginopteridales are not entirely clear but are thought to be related to changing environmental conditions and the evolution of more efficient plant reproductive strategies.

Classification

Lyginopteridales are classified within the broader group of seed ferns, Pteridospermatophyta. This classification is based on morphological characteristics, as genetic data is not available for these extinct plants. The order Lyginopteridales includes several families and genera, although the exact classification has been subject to revision as new fossil evidence is discovered and analyzed.

See Also

• Pteridospermatophyta
• Seed ferns
• Paleozoic
• Carboniferous
• Permian

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