Mesozoic plants | PPT

INTRODUCTION
The Mesozoic era was a time of great changes, not only
in animals but also in the terrestrial vegetation. The
Mesozoic flora was the vegetation eaten by the dinosaurs,
other Reptiles and mammal Herbivores during this era.
New genus and new plants Eg: Gymnosperms first
appeared in their recognizable forms. Ferns had already
appeared in Paleozoic but their diversity and spread
increased in the Mesozoic. Conifers, Cycades and the
living fossil Ginkgo dominated and made up the forest.
Angiosperms and flowers are appeared in Mesozoic and
began to diversify and take over from the other plants.
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TIME SPAN
According to the above geological scale. Haiden,
Archean and Precambrian these three together
occupies major portion of the geological
timescale i.e, 4030 million years.
Paleozoic Era - 320 million years.
Mesozoic - 174 million years.
Cenozoic - 66 million years proceeding till now.
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MESOZOIC ERA
The Mesozoic Era, which
began some 250 million years
ago, is usually called the “Age
of Reptiles” or the “Age of
Cycadophytes”. The Mesozoic
is divided into three time
periods: the Triassic (245-208
million years ago), the
Jurassic (208-146 million
years ago), the Cretaceous
(146-65 million years ago).
The Mesozoic era occurs
between the Paleozoic and
the Cenozoic.
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PLANTS THROUGH TRIASSIC
Triassic period, in geologic time, the first period
of the Mesozoic era, it began 252 million years ago, at
the close of Permian period, and ended 201 million
years ago, when it was succeeded by the Jurassic
period. Seed ferns like Glossopteris, ferns and early
species of gymnosperms (seed plants, such as the
evergreens, in which the seeds are not enclosed)
dominate the Triassic terrain. Cycads, with tufts of
tough, palm-like leaves and a woody trunk, appeared
in the late Carboniferous and were abundant in the
Triassic.
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PLANTS THROUGH JURASSIC
The Jurassic is a geologic period and system that
extends from 201 million years ago to 145 Ma; from the
end of the Triassic to the beginning of the Cretaceous.
The Jurassic constitutes the middle period of the
Mesozoic era
Conifers were the dominant land plants of the
Jurassic
 Gymnosperms were relatively diverse during the
Jurassic period. The Conifers in particular dominated
the flora, as during the Triassic; they were the most
diverse group and constituted the majority of large
trees. Cycades and ginkgos also common in this
period 9MESOZOIC PLANTS
CYCADES
Cycads are seeded plants that are physically recognized by
the presence of a thick and wooded trunk and a crown of
stiff evergreen leaves. Of these plants individuals of the
species are all male or all female and both are known to
have exceptionally long life spans. Cycad plants are found
throughout the world even today but prefer to thrive in
areas that have tropical or subtropical climates. These
plants first made an appearance in the early Permian era
and are still thriving today! A significant number of
herbivorous dinosaurs fed on cycads because of their
hardy nature, their bountiful presence and the fact that
they grow both close to the ground and high from the
ground
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CYCADEOID
Cycadeoids are a group of plants otherwise known as
Bennettitales. This order of plants became apparent in the
Triassic era and is believed to have become extinct in the
Cretaceous period. The Cycadeoids were seed plants that
generally look much like Cycads in terms of physical
appearance. The Cycadeoids are separated in to two groups,
Cycadeoidaceae and Williamsoniaceae. Each of these groups
contains a number of individual plant species. The
Cycadeoidaceae include: Cycadeoidea, Cycadekka and
Monanthesia. These plants are all characterized by thick trunks
and the presence of cones. The Williamsoniaceae include:
Williamsonia, Wielandella, Williamsoniella and Ischnophyton.
These species of plant had much more slender trunks that
branch and cones that are used for reproduction.
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CONIFERS
Conifers are known by any number of names including:
Pinophyta, Coniderophyta or Coniferae made their first
appearance in the late Carboniferous period and remain a
thriving plant family today. Like cycads and cycadeoids
conifers are cone bearing. Only a few of the conifers
known today are recognized as plants, most of this species
are woody trees such as Douglas-firs, cypresses, junipers
and firs. There are currently 68 genera and 630 living
species of conifer; however, this variety of plant was
certainly not as bountiful back in the Jurassic period. One
thing that makes this plant variety particularly interesting
is the fact that it seemed to thrive as a result of the
Permian-Triassic extinction event that had such a
devastating effect on many other living things.
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GINKGO
Ginkgophytes or simply ginkgo is known as a genus of plant
that does not flower and is currently known only by a single
living species: ginkgo biloba. Ginkgo biloba is seen by many as a
living fossil and is taken in the modern day as a supplement. Is
it believed that the ginkgo plant dates back as far as 199.6
million years ago to the beginning of the Jurassic era and it
currently still thrives. The Jurassic period was a particularly
beneficial era for the ginkgo plant not only because it saw its
beginning but also because it was able to diversify. Throughout
the middle of the Jurassic period the ginkgo plant diversified
and came to spread throughout Laurasia and this diversification
carried on through the beginning of the Cretaceous period. By
the middle of the Cretaceous period however, this plant began
to decline in diversity. Today there is only one single specimen
of this plant life left living, this species of ginkgo was able to
thrive in China where all other gingko plants died out in the
rest of the world.
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PLANTS THROUGH CRETACEOUS
The first appearance of the flowering plants, also called the
angiosperms or Anthophyta. First appearing in the Lower Cretaceous
around 125 million years ago, the flowering plants first radiated in the
middle Cretaceous, about 100 million years ago. Early angiosperms did
not develop shrub- or tree-like morphologies, but by the close of the
Cretaceous, a number of forms had evolved that any modern botanist
would recognize. The angiosperms thrived in a variety of
environments such as areas with damper climates, habitats favored by
cycads and cycadeoids, and riparian zones. High southern latitudes
were not invaded by angiosperms until the end of the Cretaceous.
Ferns dominated open, dry and/or low-nutrient lands. Typical Jurassic
vegetation, including conifers, cycads, and other gymnosperms,
continued on into the Lower Cretaceous without significant changes.
Swamps were dominated by conifers and angiosperm dicots.
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Some of the common plant genera
of the Mesozoic era
EQUISETITES;
These small horsetails had
ribbed stems, with spores
present in terminal cones.
Individual leaves were
jointed, linear, or grass like,
with up to 30 per whorl.
Scale leaves clothed the base
of the leaf. The plant spread
by underground stems and
tubers. Equisetites lived in
wetland conditions. Its
tubers are often found in
fossil soils. Typical height 20
ft.
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OSMUNDA
This is a fern with a short
stem, large ordinary
fronds, and specialized
spore-bearing fronds. It is
probable that fossil plants
of this genus were to be
found near water, often in
warm, temperate wetland
areas. Typical height 6-1/2
ft. All ferns require a
moderately damp habitat
for reproduction.
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WILLIAM SONIA
This plant resembled a
small tree with
diamond-patterned bark
and palm like leaves. Its
most interesting aspect
was its star-shaped
flowers. Williamsonia
grew in tropical tree-
fern forests. Typical
height 10 ft.
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PACHYPTERIS
A common constituent of
many Jurassic floras,
Pachypteris had small
fronds with a lobed
appearance. It was one of
the last of the
Pteridosperms (seed ferns)
and became extinct during
the Cretaceous period.
Pachypteris grew in salt
marshes. Typical height 6-
1/2 ft.
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SEQUOIA
This genus includes very
large trees. Small, very
globular cones are a
feature of these plants.
The cones do not often
disintegrate, even as
fossils, but open to let the
seeds fall out. Redwoods
once formed extensive
forests in sub-tropical
regions of the world.
Typical height 230 ft.
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ARAUCARIA
The leaves are small and
toothlike. The cones are
large and very spiny.
Seeds are present at the
base of the bracts. This
genus grew in
subtropical mountain
forests. Typical height
100 ft.
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CONCLUSION
In conclusion Plant fossils are very rare and poor in
preservation. Fossilization of plants occur with certain
conditions.
Plant fossils records are incomplete.
Plants are FIXIST. Not in migration, adjust to climates
Helps in establishing the paleoclimates.
Plant fossils study through ages helps to understand the
evolution during Geological age.
Dominant plants in Mesozoic Gymnosperms like cycas
and other family are seen in fossil record.
During terminal part of Mesozoic the origin of flowering
plants like Angiosperms occurs. Which have become
dominant during Cenozoic.
PLANT FOSSILS HELPS TO RECONSTRUCT PALEOCLIMATE OF PAST.
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