FOSSIL PLANTS Updated

8/16/2019 FOSSIL PLANTS Updated

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FOSSIL PLANTS

RESEARCH AND PRESENTED BY:JOSHITA SAINI


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CONTENTSS.No Title Slide No.

1. What Are Fossils 1

. T!"es O# Fossils $

%. &eolo'i(al Ti)e S(ale *

$. What Are Pterido"h!tes+ ,

*. Fossil Pterido"h!tes -

,. What Are &!)os"er)s+ 1

-. Fossil &!)os"er)s

/. Re#ere(es


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WHAT ARE FOSSILS?

• Fossils derived from Latin word fossus, means literally“having been dug up”.

• Are the preserved remains or traces of animals, plants, andother organisms from the remote past.

• Totality of fossils, both discovered and undiscovered, andtheir placement in f ossiliferous (fossil-containing roc!formations and sedimentary layers (strata is !nown as thefossil record.

•

Palaeobotany is the study of plant fossils preserved inroc!s.

• The word “ Fossil ” has been defined as “any evidence of prehistoric life”.


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TYPES OF FOSSILS

• Petrifaction " #ormed because of the slow infiltration of tissues by someminerals li!e calcium, silica or magnesium.

•$rganic matter is replaced by mineral matter. Almost all the details ofeven cell walls are visible under the microscope.

•Compressions or mummification " %arts of the organism are flattened bythe vertical pressure of the overlying roc!s. $utlines of epidermal cells,hair, stomata, etc can be studied by these fossils.

• &o internal cellular details are preserved.

• Impressions " 'aterial of the plant disorganies but the impressionremains. #ormed because of the burial of the parts of the plant in the soil,later on harden into roc!. $nly e)ternal features of the plant are preserved.

•Casts or molds " formed when an organism, submerged in watercontaining lime, remains covered by a crust of mineral matter. *ecay ofsuch incrusted organisms leaves a cast or mold.

•+asts e)hibit nothing of the original tissues of the organisms.


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GEOLOGICAL TIME SCALE


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WHAT ARE PTERIDOPHYTES?


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FOSSIL PTERIDOPHYTES

• Division Psilophytopsida (e.g. hynia,

orneophyton, osterophyllum

• Lepidodendrales of Lycopsida

• Hyeniales (e.g. yenia, Sphenophyllales (e.g.

/phenophyllum of /phenopsida

• Cladoxylales of Pteropsida


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RHYNIA

• *iscovered from the middle devonian roc!s of Rhynie in Scotland (about 012 million

years ago• epresented by two species " R ma!or " R g#ynne$vaughani.

• %lant body sporophytic, sporophytes of . ma3or were larger than R g#ynne$

vaughani

• %lants had dichotomously branched rhiome. #rom the rhiome, developed many

dichotomously branched erect aerial shoots towards the upper side and many rhioidstowards the lower side.

• oots were absent.

• /hoots were photosynthetic in nature and had stomata all over.

• Reproductive Structures " sporangia present at the tips of some aerial shoots.

• $val to cylindrical in shape with distal pointed end and a broad basal end.

• Sporangia of R ma!or were larger than that of . gwynne-vaughani.

• Large no. of spores present inside, homosporous, arranged in tetrads.


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ANATOMY OF AERIAL SHOOT

• *ifferentiated into epidermis, corte) and stele.

• $utermost layer- epidermis covered by heavy cuticle. The continuity of epidermis was bro!en by many

stomata.

• 4nside the epidermis was a well-developed region of corte). 4t was differentiated into inner and outer corte).

• The outer corte) or hypodermis was 5-6 cells thic! and without any intercellular spaces. The inner corte) was

made up of many spherical cells having large intercellular spaces. 4nner corte) had a direct connection with

the stomata through these intercellular spaces.

• 7ndodermis and pericycle layer absent. /tele was simple protostele.

T.S aerial shoot Rh!ia


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HORNEOPHYTON

• Horneophyton lignieri, similar to hynia.

• /maller, more slender, more freely branched stems.

• Aerial parts were without any appendages.

• 8nderground portions had short-lobed tuberous corn-li!e structures.

•

/tele was protostelic.• %resence of large no. non-septate fungal hyphae in many tubers

• /porangia were terminal, sessile, present on the tips of stem 9 no

uniformity in shape.

• /porangia were surrounded by thic! wall and had a sterile columella.

• 4n bifid sporangium, colimella was also bifid.

• /pores were present in tetrads.


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YARRAVIA

• %arravia was a generic name given to the reproductive bodies.

• belongs to /ilurian period 9 discovered in Australia.

• &a!ed a)es terminated into large synangia.

• 7ach synangium consisted of many elongated sporangia

• &o spores were identified within sporangia.


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COOKSONIA

• :elongs to late /ilurian age 9 discovered in ;reat :ritain.

• /ome wor!ers give the generic name +oo!sonia to the

reproductive bodies of


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ZOSTEROPHYLLUM

• =ell-!nown vascular plants from Silurian age.

• epresented by only 0 species- myretonianum& ' australianum& " '

rhenanum

• /pecies described from (ld Red Sandstone of Scotland .

• %lant body consisted of a dichotomously branched vegetative system

bearing many fertile branches.

• #ertile branches terminated into sporangia-bearing spi!e li!e structures.

• . rhenanum was described from the Lower *evonian in ;ermany.

%artially submerged species of 'osterophyllum.


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LEPIDODENDRALES

• 7)tinct order of Lycopsida.

• %lants originated during the 8pper *evonian period and

e)tinct by the end of the %ermian period.

• %lants were big trees e.g. Lepidodendron

•

Lepidodendron- highly branched genus, branching wasdichotomous and ultimate branches bore small leaves.

• $n the lower side, the trun! was anchored by four main

horiontal radiating arm li!e a)es. /everal spirally

arranged lateral appendages were present on thesubdivisions of these branches. These are called

stigmarian appendages or stigmarian roots.

• Lepidodendrales were possibly heterosporous plants.


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HYENIA ELEGANS

• *iscovered from the )iddle Devonian roc*s.• ad stout horiontal rhiome bearing sterile and fertile erect branches

• /terile branches bore for!ed appendages on their nodes, which functioned

as leaves.

• #ertile branches bore whorls of sporangiophores

• Two segments of each fertile whorl were refle)ed and each of them bore

two sporangia.


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SPHENOPHYLLUM

•

Appeared in 8pper *evonian and became e)tinct in the Triassic period.• +entral a)is of the aerial shoots was slender, irregularly branched.

• /tems were delicate and divisible into nodes and internodes.

• Leaves present on the nodes, arranged in whorls, in multiples of 0.

• >-51 leaves were present at each node.

• 7ntire as well as dichotomously divided leaves were also present on thesame shoot in some species, showing heterophyllous nature.


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INTERNAL ORGANIZATION OF STEM

•/tem had triangular mass of primary )ylem in the centre.

•/tele was actinostelic and the exarch protoxylem was present at

the angles of the actinostele.

•+orte) consisted of peripheral region of thic! walled cells and

an inner region of thin walled cells.

•/econdary growth by means of cambium was seen in the stems.

•$utside the primary )ylem developed a ring of cambium.

•%itted trachieds and )ylem parenchyma were present in the

secondary wood.

•%eriderm developed in the inner portion of the corte) after the

start of cambial activity.


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CALAMITALES

•'embers of this fossil order appeared in +pper Devonian and

became e)tinct in early ,riassic period .

• %lant body was sporophytic& sporophytes were very large and

tree-li!e.

•/tems and branches showed considerable secondary growth.

• =horls of sporangiophore, usually alternating with the sterile

bracts, were present in strobili


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CLADOXYLON

• %lants from 'iddle *evonian

• Thic! stem, branched irregularly.

• /ome of the branches had fan shaped, deeply divided leaves showing a

series of dichotomies.

•

/porangium present at the tip of each dichotomously diving branch of sonfan shaped leaves.

• ighly comp

• le) type of polystelic vascular system.


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COENOPTERIDALES

•$ccurred in the roc!s of 8pper *evonian, carboniferous and Permian era

• #ossil group of fascinating fern-li!e plants.

• /howed wide range of growth habits, some had creeping stems

(:otryopteris cylindrica, had erct trun!s (ygopteris primaria.• Lac! of clear cut differentiation between the leaves and stem in most

of the members.

• %lants had large frond li!e spirally arranged appendages. #ronds

were 0* in their branching pattern.

• ?ascular system of stem was usually protostelic.

• /porangia were generally large, oval, pedicellate and attached

terminally on the fertile branches.

• All members were homosporous, e)cept Stauropteris burntislandica


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WHAT ARE GYMNOSPERMS?


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Fossil '!)os"er)s

• Ar(haeo"teris

• 0!'io"teris oldha)ia

•

&losso"teris• Willia)soia

• Peto!lo


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ARCHAEOPTERIS

• eported from the roc!s of the upper *evonian period of &orth America, ussia.

• ad large fern li!e fronds.

• #erns were bipinnately branched had all the pinnae developed in one plane

• 7ach pinnule had a single vascular bundle, which soon became dichotomously

branched .

• The fertile fronds had sporangia

• The sporangia replaced the pinnules of some of the lower pinnae in the fertile fronds.• 'ost of the species appeared to be homosporous.

• - latifolia was heterosporous and possessed both microspores and mega spores on

the same plant.

• 4t possessed two !inds of sporangia .

• )egasporangia possessed about 5> spores and microsporangia about 522 or morespores.


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Lyginopteris Oldhamia

• %lants are vine-li!e with large fronds.• The stem was erect, branched, @mmto6mm in diameter.

• The leaves were bi-or tripinnately compound and arranged

spirally on the stem.

• The pinnae were borne at right angles to rachis and were

arranged opposite to each other.

• The pinnae bore pinnules.


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T.S STEM

Lyginopteris Oldhamia


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T.S OF STEM

• &e)t to 7pidermis is the outer corte) which consists of

radially broadened fibrous strands that form a vertical

networ!.

• The inner corte) consists of ordinary parenchymatous

cells. &e)t to the corte) is the pericycle which consistsof sclerotic cells called sclerotic nests.

• &e)t to the pericycle are five strands of primary

vascular bundles. These are separated by

parenchymatous areas. 7ach vascular bundle is mesarchand consists of primary phloem towards the outer side.

• 4n the centre there is a large pith made up of

parenchymatous cells.


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MALE FRUCTIFICATION:

CROSSOTHECA

• is 'eerall! re'arded as the )ale #r2(ti#i(atio

• I Crossotheca, a 2)3er o# 3oot sha"ed 3ilo(2lar )i(ros"ora'ia

4ere arra'ed radiall! o the 2derside o# dis(s.

• 5i(ros"ora'ia 4ere 3ore as elo'ate6 "edat a""eda'es o

the 2lti)ate "i2le o# the #rod. The #ertile #rods rese)3le )i2tehair3r2shes.

• The s"ora'ia la(7 a2l2s ad rese)3les those o# C!(as. O

dehis(e(e6 the )i(ros"ores 4ere (arried 3! 4id. The )i(ros"ores

are s"heri(al 4ith the tri8radiate )ar7i's 9trilete.


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L.S OVULE OF THE

LYGINOPTERIS OLDHAMIA


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FEMALE FRUCTIFICATION

( LAGENOSTOMA OLDHAMIA)

• dis(o;ered #or)

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FOSSIL PLANTS Updated