Paleobotany
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Palaeobotany is the study of ancient plant life through fossil records. It involves identifying and classifying plant remains from different geological eras to reconstruct ancient ecosystems and understand the evolution of plants. Some of the key developments in plant evolution identified through palaeobotanical studies include the earliest appearance of leaves, roots, woody stems, and seeds. Leaves are thought to have evolved from spiny outgrowths on stems for protection and better photosynthesis. Roots differentiated from stems and allowed plants to grow taller. The evolution of seeds increased reproductive success and biodiversity.
Paleobotany
- 1. S.Y.B.Sc. /{B} /{262} SEMESTER-4 PRAVIN PRADHAN }
- 3. Derived from Greek words “Palaeon” = old and “Botany” = study of plants. Deals with the identification of plants remains of geological age, and its reconstruction. Includes the study of terrestrial plant fossils, as well as Marine ones such as seaweeds.
- 4. Reconstruction of ancient ecological systems and climate, known as palaeoecology and palaeoclimatology respectively. Study of green plant development and evolution. Important to the field of Archaeology.
- 5. First fossil record was found in SILURIAN period of PALAEOZOIC ERA. Spores and cuticles, were found in ordovician period. Angiosperms (flowering plants) evolved during the Mesozoic, and Early Cretaceous. (approx. 130 million years ago)
- 6. A plant fossil is any preserved part of a plant that has long since died. Bits of charcoal that are only a few hundred years old. RHYNIE CHERT found in SCOTLAND bearing the fossils of mosses and lycopods. (see image beside)
- 7. LEAVES Evolved to originate as spiny outgrowths. Before the evolution of leaves, plants had the photosynthetic apparatus on the stems.
- 8. The branching pattern of megaphyll veins may belie their origin as webbed, dichotomising branches. (see image right) Leaf lamina. The leaf architecture probably arose multiple times in the plant lineage (see image left)
- 9. To protect early plants from herbivory. Better transpiration rates and gas exchange. Helps to carry out better Photosynthesis. Figure beside shows the diversity in leaves evolved according to their suitable environmental conditions.
- 10. ROOTS Organs differentiated from stems – did not arrive until later. Roots are rarely preserved in the fossil record. Their evolutionary origin is sparse. Rhizoids are prehistoric roots. Rhizoids probably evolved more than once. The root of Lepidodendrales (image beside)
- 11. provide anchorage to the substrate. provide a source of water and nutrients from the soil. allow plants to grow taller and faster. Stigmaria, a common fossil tree root. (image beside)
- 12. Stems Ferns were the first to have a growth of woody habit. Progymnosperms were the first plants to develop true wood. The trunk of early tree fern Psaronius, showing internal-structure. (image beside)
- 13. The most obvious advantage is the harvesting of more sunlight for photosynthesis. Spores can be blown greater distances if they start higher. Provided support and water transport. External mold of Lepidodendron trunk. (image beside)
- 14. SEEDS Germination of microgametophytes and megagametophytes, paved the way for seeds. Seed plants from Belgium has been identified the earliest seed plants - about 20 million years. The first "spermatophytes" (seed plants) i.e. the first plants to bear true seeds are called "pteridosperms“ (seed ferns). The fossil seed Trigonocarpus (image beside)
- 15. increased the success rate of fertilised gametophytes. increases the biodiversity of forests. Helps the plant to survive for generations. The transitional fossil of seed of Runcaria. (image beside)
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