Download fossil record

14.1
• I can recognize patterns of change in
populations over time
• I can give examples of evidence that supports
evolution
• I can describe fossils of early human ancestors
• The changes in a population over time
• An organism changes as it grows and develops, but
this is NOT evolution
• Evolution occurs within populations
• As organisms in a population die off, new organisms
are born into it
Levels of Organization
Biosphere
Ecosystem
Community
Population
Organism
• Genes determine the traits of all living things
• Evolution involves changes in a population’s gene pool
• Genes can be changed by radiation, chemicals in the
environment, and if they are copied incorrectly
• Mutations in gametes do not affect the parent, but
instead they get passed on to the offspring
• Mutations can cause harmful changes in traits
• A lethal mutation is one that results in an organism’s
death
• Most mutations, though, are favorable and are passed
on to offspring
• As the mutation is passed on to future generations, it
becomes more and more common with the population
• If a population’s environment changes, members
of the population that have certain favorable
traits maybe more likely to survive
• Evolution occurs slowly as these favorable traits
are passed on from one generation to the next
• A change in the environment may split a population
into two isolated groups
• A large river, or canyon may form and divide a
population
• The single population now becomes two populations
that have no contact with each other
• Different mutations can occur which result in different
genes
• Sometimes a population can be divided if organisms
move out of the area
• For example, organisms may travel from the mainland
to a neighboring island
• Over time, if enough change occurs, the island
population may evolve into a new species
• Evolution
• Lethal Mutation
• Geographic Isolation
• Self-Check Questions #1-5 pg. 316
• COMPLETE SENTENCES
14.2
• Fossils are the remains or traces of organisms
that lived in the past
• Fossils are found in rock, tree sap, and other
materials
• Fossil comes from the Latin word fossilis,
meaning “dug up”
• Bones and teeth can remain as fossils for millions of years
• Fossils can be found in mud and bits or rock, called
sediment, at the bottom of water
• Over time, layers of sediment harden into rock and leave a
type of fossil called a mold
• Animals and insects have also been found in hardened tree
sap and frozen in ice
• Paleontologists are scientists who study life in the past,
or fossils
• Their findings have formed a fossil record, which is a
history of life on Earth, based on fossils that have been
discovered
• Fossil records also show how organisms have changed
over time
• Life on Earth dates back 3.5 billion years (geologic
time scale) pg. 319
• Scientists can tell how old a fossil is by comparing its
location in rock
• Fossils in lower layers of rock are older than fossils in
upper layers of rock
• Scientists can also use radioactive materials to date
fossils
• Radioactive materials give off energy as they change
to another substance over time
• When a species disappears, it is said to be extinct
• A fossil record will show when different species lived
and then disappeared from Earth
• As species become extinct, new species appear
• Mass extinctions (large numbers of species became
extinct) are caused by major changes in environment
• Fossils show how groups of organisms have
changed over time
• Horses and humans are examples (pg. 321)
• Scientists learn more about fossils by comparing them
to living organisms
• The look for similar structures, such as teeth and bones
• Fossils have proven that certain species have evolved:
• Certain fish have evolved into amphibians
• Reptiles have evolved into mammals
• Some reptiles have evolved into birds
Fossil
Sediment
Fossil Record
Extinct
Self-Check Questions #1-5 pg. 323
COMPLETE SENTENCES