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Flowering plants’ showy petals are
petals are thought to be modified stamens
which attract insects, birds and other pollinators.
Today, flowering plants are extremely diverse;
they even inhabit the water (duckweed) and
the air (Spanish moss). Some flowering plants
are parasitic and even carnivorous! Grasses,
which today cover 30% of the Earth’s
land surface and provide humans with more
than 50% of the carbohydrates we eat (think
of corn, rice, bread, cereal…) did
not evolve until the latest Cretaceous.
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The earliest flowering plants are
thought to have been weedy shrubs
that lived alongside streams. One
of these early groups to evolve
was the water lily family.
- Magnolias
Magnolias (Magnoliales)
were among the first groups of flowering
plants to evolve. Fossils of Magnolia-like
plants are known from early-mid
Cretaceous sediments (Aptian-Albian,
~112 Ma) in North America. Because
Magnolia, and many other early flowers
have large bisexual flowers with
very many floral parts (carpels,
stamens) compared to later (more
“derived”) groups of
flowering plants, it was long thought
that this represented the “primitive”(ancestral)
condition from which other flower
types evolved. Now we know that
both very large flowers with numerous
parts (such as Magnolia,) and simple
flowers with few floral parts, existed
among the earliest flowers.
Magnolia
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Paleontologists have suggested
a few explanations for why flowering
plants evolved at the end of the dinosaur
era (~140 Ma):
- The environment during the Cretaceous
– which was warm and dry –
favored the evolution of flowering
plants
- Flowering evolved in conjunction
with plant-eating dinosaurs
- Flowering plants evolved in conjunction
with insects
It is also possible that flowering
plants DID evolve earlier than the
late Mesozoic, but the plants were
so small and fragile they didn’t
fossilize.
Unfortunately, none
of these hypotheses are well supported. |
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GIANTS:
African Dinosaurs created by Project Exploration
