PALAEOBOTANY Dr Sibi C Varghese Guest Lecturer Dept

PALAEOBOTANY Dr. Sibi C Varghese Guest Lecturer Dept. of Botany Nirmala College, Muvattupuzha

FOSSILS “Fossils are the relic of some former living beings, embedded in the superficial deposits of the past geological periods. ” Not only include preserved remains of plants and animals but any associated substances such as some chemical molecules constituting body parts-chemical fossils. Hard tissues are better preserved

NOMENCLATURE OF FOSSILS Complete Only So plant rearly preserved fragments are found at different times difficult to organize into a complete plant and to assign appropriate name

NOMENCLATURE OF FOSSILS Suggestion of Sixth International Botanical Congress (1935) Each fossilised part is given a name =status of a genus Unlike living plants, generic name is given only to parts without indicating to which plant it belongs Each part represents a form genus/organ genus/artificial genus Complete plant constructed by putting together these form genera on the basis of similarity and period to which it belongs

NOMENCLATURE OF FOSSILS Roots Kaloxylon hookeri Seeds Stem Lagenostoma comaxi Lyginopteris oldhamia Calymmatothec a hoeninghau Rachis Leaf Rhacopteris aspera Sphenopteris hoeninghausi

RULES OF NAMING FORM GENERA Suffix signifies different parts -dendron stem -phyllum leaf: Lepidophyllum -xylon woody part of plant: Dadoxylon -spermum, -carpon, -carpus, -stoma seed : Corytospermum, Mazocarpon, Sterocarpus, Lage nostoma -theca microsporangia: Polytheca -strobus cone: Androstrobus

BIOLOGICAL ASPECTS OF PALAEOBOTANICAL STUDIES Study of external and internal structure and distribution of fossils Identifying evidences in support of phylogeny & evolution of plant groups Assertion of climatic and environmental condictions of geological period under study Correlation of palaeoclimates with the distribution of plants

GEOLOGICAL ASPECTS OF PALAEOBOTANICAL STUDIES Determination of age of rocks Geographical distribution of coal and water Supply of useful information in the exploration of fossil fuels

FOSSILIZATION The process of preservation of dead organisms or their parts in the form of fossils. Can be entire organism/ hard part/ mould /cast of an organism/or its parts or imprint of a leaf on a stone.

FOSSIL RECORD The totality of fossils, discovered and undiscovered, and their placement in fossiliferous (fossil containing) rock formations and sedimentary layers is known as fossil record. Fossils are direct evidence for the existence of pre-historic organisms.

THEORIES ON FOSSILIZATION v Replacement v Infiltration theory

REPLACEMENT THEORY Replacement of molecules of original plant material by molecules of minerals in soil solution Occurs due to hydrolysis or weathering of organic substances in plant body

INFILTRATION THEORY Occurs due to infiltration or precipitation of substance through plant cell wall Burial Plant body undergoes partial disintegration Released free carbons become carbonates by reacting with infiltrated Ca/Mg etc.

FACTORS EFFECTING FOSSILIZATION § § Nature of plant (thin/delicate/hard) Rapidity by which material is prevented from decay by organisms Changes to which rocks are subjected during/after the burial of plant part Extent of mineralisation

TYPES OF FOSSILS Ø Compression fossils Ø Petrifactions Ø Incrustations Ø Impressions Ø Compaction Ø Coal fossils/mummified plants balls Ø Amber Ø Leaf coal/Paper coal Ø Actual remains

COMPRESSION FOSSILS Commonest type Lepidodendron fossil

PETRIFICATION External and internal structures are preserved Organic parts protected from decay but mineralization proceeds

INCRUSTATIONS Common; Good for study of morphology External preserved, internal structures destroyed Pith cast of a Calamites stem Eucalamite

IMPRESSIONS ØDoes not contain organic substance ØShows venation pattern and cuticular details ØUseful for studying external features

COMPACTION FOSSILS/MUMMYFIED PLANTS ØCompressed by vertical pressure ØIntervening matrix absent ØLeathery leaves/hard frits/seeds may be mummyfied

COAL BALLS • Spherical plant organs • Formed by infiltration of calcium carbonate/magnesium carbonte/iron sulphate into buried plants

AMBER Resinous exceretions of fossil coniferous trees Exuded due to wound or decay Animals and plants got trapped in these

LEAF COAL/PAPER COAL Thin dead leaves dispersed in organic matter Inner tissue destroyed ; successive layers of cuticle

ACTUAL REMAINS Relatively Due younger to low temperature and absence of air decomposition is prevented

PSEUDOFOSSILS

GEOLOGICAL TIME SCALE Total lifespan of Earth from its origin about 4600 billion years ago Time chart or time scale that subdivides the Earth’s history into geological time units Subdivision of history based on time and Earth’s stratification Based on time: Eons (largest) Eras Periods Epochs Based on stratification: Systems, series, stages, zones

ARCHAEOZOIC ERA (PRECAMBRIAN PERIOD) Before 4000 million years ago Origin of Erath and emergence of life Very few fossils formed

PALAEOZOIC ERA -6 periods -Aquatic and land plants -First fossils of land plants -Age of seed ferns Manograptus Sporogonites Psilophyton

PALAEOZOIC ERA

Psilopsida Lycopsids Sphenopsids

MESOZOIC ERA Triassic, Jurassic, Cretaceous periods Age of cycads Negligible number of flowering plants Angiosperms formed majority vegetation in cretaceous period araliaceae Salicaceae Moraceae

COENOZOIC ERA Age of Angiosperms Tertiary Period Palaeocene Quarternary period Eocene Pliocene Oligocene Miocene Pleistocence Holocene (Glacial) (Recent)

FOSSIL PTERIDOPHYTES Rhynia gwynne-vaughanii fossil

WILLIAMSONIA

PALMOXYLON: ANGIOSPERM FOSSIL

PROF. BIRBAL SAHNI : FATHER OF INDIAN PALAEOBOTANY

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