Transcript GR Fossils and Other Evidence

AGENDA – 2/11/15
• Today’s Objective:
• We will discuss how fossils, anatomical
structures, DNA, and embryology show evidence
in evolution and evolutionary relationships.
• Bell-Ringer – Homology vs Analogy
• Finish Fossils and Evidence notes
• Natural Selection Test Corrections
AGENDA – 2/11/15
• Today’s Objective:
• We will discuss how fossils, anatomical
structures, DNA, and embryology show evidence
in evolution and evolutionary relationships.
• 4.1 --- Test Scores
• Fossils and Evidence notes
EVIDENCE OF CHANGE OVER TIME
• There are several places we can see evidence of
evolution/evolutionary relationships:
-fossils,
-studying similarities in anatomy,
- biochemistry/DNA,
-and embryology.
• Fossils are evidence of organisms that lived long ago
that are preserved in Earth’s rocks.
TYPES OF FOSSILS
Fossils Types
Formation
A trace fossil is any indirect evidence
Trace fossils
Casts
left by an animal and may include a
footprint, a trail, or a burrow.
When minerals in rocks fill a space
left by a decayed organism, they make
a replica, or cast, of the organism.
A mold forms when an organism is
Molds
Petrified
fossils
Amber-Preserved
or
frozen fossils
buried in sediment and then decays,
leaving an empty space.
Petrified-minerals sometimes penetrate
and replace the hard parts of an organism
At times, an entire organism was
quickly trapped in ice or tree sap that
hardened into amber.
• Paleontologists, scientists who study ancient life, are
like detectives who use fossils to understand events
that happened long ago.
• They use fossils to determine the kinds of organisms
that lived during the past and sometimes to learn
about their behavior.
• For fossils to form, organisms
usually have to be buried in mud,
sand, or clay soon after they die.
• Fossils are not usually found in other types of rock because of the ways
those rocks
form.
• Most
fossils
are found in sedimentary rocks.
rocksthe
form
at relatively
low temperatures
and
pressures
• These
For example,
conditions
under which
metamorphic rocks
form
often
that
may
damage
to the
organism.
destroy
anyprevent
fossils that
were in the
original
sedimentary rock.
• Few organisms become fossilized because, without
burial, bacteria and fungi immediately decompose
their dead bodies.
• Occasionally, however, organisms do become fossils
in a process that usually takes many years.
How fossils form
• Scientists use a variety of methods to determine the
age of fossils.
• Relative dating
• This method basically indicates that the fossils found
closer to the surface are younger, and the fossils
found in deeper strata are more primitive (older).
(in undisturbed ground)
• This method does not
give a specific age of
the fossil or rock.
• Using this principle, scientists can determine relative
age and the order of appearance of the species that
are preserved as fossils in the layers.
• To find the specific ages of rocks, scientists use
absolute dating, also called Radiometric Dating.
• In this type of dating scientists use radioactive atoms
to determine the absolute age of objects.
As specific atoms decay they emit radiation and lose
electrons, which causes them to turn into a different
element.
So- these atoms change from one thing into something else
over time- and they do this at a constant rate.
• The half-life of a radioactive atom is the time it takes
for half of that atom in a sample to decay and turn into
another element.
One form of evidence in the unity of life…..
Anatomical evidence
Science sees structural similarities as evidence that
organisms evolved from a common ancestor.
Crocodile
forelimb
Bird
wing
Whale
forelimb
Homologous
parts are similar
in structure, but
may be very
different in
specific function.
Structural features with a common evolutionary origin
are called homologous structures.
The body parts of organisms that do not have a common
evolutionary origin but are similar in function are called
analogous structures.
Analogous parts
are very different in
structure, but
perform similar
functions.
Pre-AP Bell-Ringer: 2/11/15
1. What are homologous structures?
2. What are analogous structures?
3. Give an example of each type of
structure.
ANATOMY
• Vestigial structure—a body structure in a present-day
organism that no longer serves its original purpose, but
was probably useful to an ancestor.
Video clip
BIOCHEMISTRY
Scientists believe that the fact that ALL LIVING THINGS
have A,T,C, and G in their DNA and all use the same
coding for proteins means we are all related in some
way.
EMBRYOLOGY
• The study of how similar embryos are for different
organisms (may be evidence of relation)
• An embryo is the earliest stage of growth and
development of both plants and animals.
EMBRYOLOGY
• Scientists believe the shared features in the
young embryos of different species suggest
evolution from a distant, common ancestor.
Pharyngeal
pouches
Pharyngeal
pouches
Tail
Fish
Tail
Reptile
Bird
Mammal
Chicken
Rat
Turtle