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




A cladogram is an evolutionary tree made
using cladistics.
A clade is a group of species that shares a
common ancestor.
Each species in a
clade shares
some traits with
the ancestor.
Each species in
a clade has
traits that have
changed.

Nodes
represent the
most recent
common
ancestor of a
clade.
CLADE
Tetrapoda clade

Clades can be
identified by
snipping a
branch under
a node.
Reptilia clade
Archosauria clade
Diapsida clade
Amniota clade
FEATHERS AND
TOOTHLESS
BEAKS.
SKULL OPENINGS IN
FRONT OF THE EYE AND
IN THE JAW
OPENING IN THE SIDE OF
THE SKULL
2 SKULL OPENINGS BEHIND THE EYE
EMBRYO PROTECTED BY AMNIOTIC FLUID
FOUR LIMBS WITH DIGITS
Characteristic
NODE:
Most recent common ancestor

As you move up a
cladogram, you are
building upon the
characteristics
found before it. You
are becoming more Tetrapoda clade
specific.
CLADE
Reptilia clade
Archosauria clade
Diapsida clade

Ex: Tetrapoda only
has 4 limbs.
Amniotes have 4
limbs and an embryo
protected by amniotic
fluid. Reptiles have 4
limbs, amniotic fluid
and 2 skull openings
behind the eye, etc…
Amniota clade
FEATHERS AND
TOOTHLESS
BEAKS.
SKULL OPENINGS IN
FRONT OF THE EYE AND
IN THE JAW
OPENING IN THE SIDE OF
THE SKULL
2 SKULL OPENINGS BEHIND THE EYE
EMBRYO PROTECTED BY AMNIOTIC FLUID
FOUR LIMBS WITH DIGITS
Characteristic
NODE:
Most recent common ancestor
Making a Cladogram
Let’s try to classify these animals using both their
physical characteristics and what we now
know from fossils and DNA analysis.
A. Lizard
B. Bird
C. Bat
A. Hippo
B. Walrus
C. Shark
A. Tasmanian Devil
B. Rhino
C. Walrus
A. Walrus
B. Hippo
C. Zebra
A. Lizard
B. Bird
C. Bat
A. Hippo
B. Walrus
C. Shark
A. Tasmanian Devil
B. Rhino
C. Walrus
A. Zebra
A. Walrus
B. Hippo
Arrange the animals listed below on the cladogram.
Alligator
Shark
Hippo
Zebra
Bird
Whale
Tasmanian Devil
Rhino
Possible Solutions
Even
Toes
Shelled eggs
Legs
Jaws
Hooves
Live Birth
Fur/Hair
Odd
Toes
Common Ancestry
Even
Toes
Shelled eggs
Pikaia
Where on the
cladogram would
you find the
common ancestor
for all these
animals?
Legs
Odd
Toes
Hooves
Live Birth
Fur/Hair
Where on the cladogram would
you find the common ancestor
for hippos and whales?
Jaws
Indohyus