1. KEY CONCEPT Modern classification is based on evolutionary relationships.

2. Cladistics is classification based on common ancestry.
Phylogeny is the evolutionary history for a group of species.
evidence from living species, fossil record, and molecular data
shown with branching tree diagrams

3. Cladistics is a common method to make evolutionary trees.
Cladistics is classification based on common ancestry
species placed in order that they descended from common ancestor
Glyptodon (10,000 yrs. ago)
Common ancestor to about 20 modern armadillo species

4. A cladogram is an evolutionary tree made using cladistics.
A clade is a group of species that shares a common ancestor. pg. 525 in book. Copy cladogram into notes.
Each species in a clade shares some traits with the ancestor. Forms a V. There are 6 clades in this example.
Each species in a clade has traits that have changed.

5. more closely related species share more derived characters
FOUR LIMBS WITH DIGITS
Tetrapoda clade 1
Amniota clade 2
Reptilia clade 3
Diapsida clade 4
Archosauria clade 5
EMBRYO PROTECTED BY AMNIOTIC FLUID
OPENING IN THE SIDE OF THE SKULL
SKULL OPENINGS IN FRONT OF THE EYE & IN THE JAW
FEATHERS & TOOTHLESS BEAKS.
SKULL OPENINGS BEHIND THE EYE
DERIVED CHARACTER
Derived characters are traits shared in different degrees by clade members. There are ”Characteristics”
basis of arranging
species in cladogram
more closely related species share more derived characters
represented on cladogram as hash marks

6. Nodes represent the most recent common ancestor of a clade
Nodes represent the most recent common ancestor of a clade. Where a branch splits. There are 5.
FOUR LIMBS WITH DIGITS
CLADE
Tetrapoda clade 1
Amniota clade 2
Reptilia clade 3
Diapsida clade 4
Archosauria clade 5
FEATHERS AND TOOTHLESS BEAKS.
SKULL OPENINGS IN FRONT OF THE EYE AND IN THE JAW
OPENING IN THE SIDE OF THE SKULL
SKULL OPENINGS BEHIND THE EYE
NODE
EMBRYO PROTECTED BY AMNIOTIC FLUID
Clades can be identified by snipping a branch under a node. There are 5.
DERIVED CHARACTER

7. Molecular evidence reveals species’ relatedness.
Molecular data may confirm classification based on physical similarities.
Molecular data may lead scientists to propose a new classification. (genes and proteins)
DNA is usually given the “last word” by scientists.