Phylum CHORDATA
Subphylum VERTEBRATA
Class MAMMALIA
MAMMALS!
Class Mammalia
• Endotherms • 4-chambered heart
• Produce milk for • Specialized teeth
young • Modified limbs
• Hair • Highly developed
• Diaphragms brains
MAMMALS!
Hair is
• made out of keratin (like feathers)
• developed from scales (like feathers)
• arrangement provides insulation /
waterproofing
• conserves body heat (endotherms)
MAMMALS!
Endotherms maintain constant body
temperatures
• panting (release heat)
• sweating (release heat)
• shivering (generate heat)
• raising hair (conserving heat)
MAMMALS!
Mammals have several types of GLANDS
• Scent
• Saliva
• Hormones
• Milk
• Digestive enzymes
MAMMALS!
Mammals nurse their young
• Mammary glands – secrete milk that is rich
in fats, sugars, proteins, vitamins, and
minerals
• This continues until offspring are able to eat
and digest solid food
MAMMALS!
The diaphragm aids in breathing
• muscle beneath the lungs, separating the
THORACIC (chest) cavity from the
ABDOMINAL cavity
• Expands the chest cavity, bringing in air
• Contracts and pushes air out
MAMMALS!
Mammals have a 4-chambered heart
• Left and Right Atrium
• Left and Right
Ventricle Circulation removes
• Oxygenated and waste and maintains
HOMEOSTASIS
deoxygenated blood
are entirely separated.
MAMMALS!
Mammalogists love teeth!
• you can tell what an animal eats based on its
type of teeth
• teeth are adapted to type of food eaten
• teeth are hard and fossilize more often than
other parts of the body
MAMMALS!
MAMMALS!
This mole’s pointed incisors are used to grasp
and hold small prey
MAMMALS!
A beaver’s incisors
are modified for
gnawing and can
gnaw through almost
anything.
These teeth continue
growing throughout
the animal’s lifetime.
MAMMALS!
A lion’s sharp canines
are perfect for slicing
and tearing flesh.
MAMMALS!
Premolars and molars are used for slicing,
shearing, crushing, and grinding.
MAMMALS!
Other characteristics include
• modified limbs
• complex behaviors – learning and
remembering
MAMMALS!
Mammals have complex brains
• Primates (including humans) are possibly
most intelligent
• use tools
• communicate
MAMMALS!
3 Orders of Mammals
• Monotremes (platypus and echidnas)
• Marsupials (kangaroos and oppossums)
• Placental Mammals (Chiroptera- bats;
Rodentia – rodents; Carnivora – weasels,
skunks, bears, foxes; Cetacea- whales,
dolphins; Primates- chimps, apes, monkeys,
humans)
MAMMALS!
Monotremes
• Eggs
• Only 3 species alive today (1 platypus, 2
echidnas)
• Found only in Australia and New Zealand
Flat tail,
duck beak,
webbed feet Coarse brown hair, covered in spines
MAMMALS!
Marsupials
• short period of development in mother’s
body
• period of development inside pouch
• most are found in Australia – opossum is
North American marsupial
MAMMALS!
Placental Mammals
• Over 4000 species (mostly bats and rodents)
• Young develop in the UTERUS
• Nourished by a PLACENTA
• Development inside the mother’s body
ensures protection from predators and
environment during development.
MAMMALS!
The placenta is derived from the same
membranes that surround embryos in
amniotic eggs (reptiles and birds)
Marsupials also have PLACENTAE, but is
short-lived
MAMMALS!
• smallest mammals are shrews and bats and
weigh as little as 3 grams
• largest is the blue whale –
160,000 kg! (352,739 lbs!)
Origin of Mammals
• The first placental mammals appeared in the fossils
record about 125 million years ago.
• Scientists trace the
origins of placental
mammals from a group
of mouse-sized animals
to a group of reptilian
ancestors called
therapsids.
Origin of Mammals
• Therapsids had features of both reptiles and mammals.
• They existed between 270 and 180 million years ago.
Origin of Mammals
• The mass extinction of the dinosaurs at the end
of the Mesozoic Era, along with the breaking
apart of Pangaea and changes in climate, opened
up new niches for early mammals to fill.
• The Cenozoic Era (65 million years to present) is
sometimes called the golden age of mammals because
of the dramatic increase in their numbers and
diversity.