Chapter
26
Quizzes:
Self
Activities
Chapter
Cum.
Videos
Movies
Words
Appendix
Summary
Art
Art
Unit 5: The Evolutionary History of Diversity
The Tree of Life
Review
The 4.6 billion years of earth's history is divided into three
geologic
, which are further divided into
,
, and
.
There have been several episodes of
mass
, but they were replaced by forms that evolved from the survivors; the trend has been an
of diversity over time.
The
(PT)
extinction
was the most
severe,
and claimed over 90% of marine species. The
(KT)
extinction
is famous for the
disappearance
of
.
were Earth’s sole inhabitants from 3.5 to about
billion years ago. The oldest known
fossils
are
Cyanobacteria were
photosynthetic
which released
oxygen,
allowing the evolution of
organisms to obtain energy through
cellular
.
The first eukaryotes probably evolved from the
of small prokaryotes living within larger host cells and developing into
organelles
such as mitochondria and chloroplasts.
Multicellular eukaryotes diversified in the late Proterozoic eon, after
Earth
started to thaw.
The first multicellular organisms were
,
collections
of autonomously
cells.
Most of the major animal
phyla,
including the
first
, appeared during the early
period in what is known as the
Explosion.
Plants
first colonized land during the
period in the
company
of
, followed by
.
Humans evolved from
tetrapods
during the
epoch. If the
clock
of Earth’s history were scaled to represent an
hour,
humans appeared about one
ago.
The
movement
of the Earth's
due to
continental
has great impact on the habitats in which organisms
live,
and shaped the diversity of life on Earth.
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May 8, 2008
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