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What do
you see in
this
picture?
Fossils
 Anatomy
 Development
 Biological
Molecules
 Models
 Examples

FOSSILS
 Preserved
or
mineralized
remains
 Studied by
Paleontologists
Fossils are structures formed from…



An animal is buried by sediment
Burial takes place on the ocean
floor, in swamps, in mud, or in tar
pits
The tissue is replaced by harder
minerals
FOSSILS
Fossils found in
older rock are
different from
those found in
newer rock
 The further you
dig down, the
longer ago the
species lived on
earth
Horseshoe crab: still alive today!

550 million years old:
Ediacara – oldest animal fossil
FOSSILS

Radiometric dating:
measure
radioactive
isotopes
 Half-life: time it
takes for ½ of a
given amount
of radioisotope
to decay
Comparing Anatomy

Homologous:
Similar structural
setup that likely
evolved from a
common ancestor.

Examples: Human
arm, cat leg, whale fin,
bat wing
Comparing Anatomy


Analogous: Structures
that are similar in
function but not
inherited from common
ancestors
Examples:
Pterodactyl, bat, bird
& insect wings
Comparing Anatomy
 Vestigial:
Structures
reduced in size from
lack of use

tailbone,
appendix, python hip,
whale legs
Examples:
Anatomy: Vestigial Structures
 Blind
Mole Rat
 Eyes covered with a thin layer of
skin
Anatomy: Embryology
All vertebrates
have…
 Dorsal hollow
nerve cord
 Notocord
 Gill slits
 Post anal tail
Biological Molecules
 All
living things have the same
4 base pairs in their DNA
 Amino acid similarities
between organisms

The more differences there are, the
further your common ancestor was
Speed of Evolution


Gradualism; slowly
over a long period of
time
Punctuated
equilibrium; rapid
burst of changes
followed by periods
of little change
Speciation
The
process by
which new
organisms
form
Adaptive Radiation
 The
evolution
of many
different
species from a
single ancestor
to occupy
many different
niches
Modes of Evolution
Co-Evolution: 2 or more species
that interact and evolve together
 EX: Plants & their pollinators

Convergent Evolution

Unrelated organisms living in similar
ecosystems developing similar traits


Marsupials in Australia compared to
other mammals
Analogous structures develop:
similar function, different structures

Bat wing and an insect wing
Divergent Evolution

Related organisms evolving into new
and different species


Darwin’s finches, Hawaiian fruit flies
Homolgous structures develop: show
a similar ancestry

Whale fin and a human arm
Adaptations

The process by which an organism becomes better
suited to its environment





Attract mates
Avoid predators
Capture prey
Blend into environment, camouflage
Compete against another species for resources

Remember: competition arise when 2 or more population
occupy the same
niche
Classification of Living Things
All living things
are grouped
by similarities
 The “tree of
life” shows
how all living
things are
connected

What if…
There are so many
unanswered questions
Ponder this….
Scientists
 Lamarck:
Theory of
Acquired
Characteristics
 Use &
Disuse
Scientists
 Charles
Darwin
 Theory of
Evolution by
means of
Natural
Selection
Scientists





Variation exists in a population
Organisms compete for resources
More offspring are born than can survive
The offspring with the favorable traits are
more likely to survive and pass on those traits
Survival of the Fittest
Scientists


Traveled to the Galapagos Islands
Observed many different species of finches
that all occupied different niches