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Prototheria (4 species) = egg-laying monotremes Theria = live birth Metatheria (~280 species) = viviparous Eutheria (~4500 species) = placental birth
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Mammalia class:Mammalia subclass:1.Prototheria
2.Theria infraclass:Metatheria, Eutheria Prototheria (4 species) =
egg-laying monotremes
Theria = live birth Metatheria (~280 species) = viviparous Eutheria
(~4500 species) = placental birth Warm blooded Have fur or hair
Suckle young 3 middle ear bones
Class Mammalia Characteristics Warm blooded Have fur or hair Suckle
young 3 middle ear bones A Guide to characteristics of Class
Mammalia The Class Mammalia is well represented in Southern Africa.
There are 293 species of land mammals and 37 species of marine
mammals in the Southern African subregion. That is 330 of the
around 5000 mammal species found on Earth! Class Mammalia -- all
mammals share three characteristics not found in other animals: 3
middle ear bones; hair; and the production of milk by modified
sweat glands called mammary glands. Mammals hear sounds after they
are transmitted from the outside world to their inner ears by a
chain of three bones, the malleus, incus, and stapes. Two of these,
the malleus and incus, are derived from bones involved in jaw
articulation in most other vertebrates. Mammals have hair. Adults
of some species lose most of their hair, but hair is present at
least during some phase of the ontogeny of all species. Mammalian
hair, made of a protein called keratin, serves at least four
functions. First, it slows the exchange of heat with the
environment (insulation). Second, specialized hairs (whiskers or
"vibrissae") have a sensory function, letting the owner know when
it is in contact with an object in its external environment. These
hairs are often richly innervated and well-supplied with muscles
that control their position. Third, through their color and
pattern, hairs affect the appearance of a mammal. They may serve to
camouflage, to announce the presence of especially good defense
systems (for example, the conspicuous color pattern of a skunk is a
warning to predators), or to communicate social information (for
example, threats, such as the erect hair on the back of a wolf;
sex, such as the different colors of male and female capuchin
monkeys; presence of danger, such as the white underside of the
tail of a whitetailed deer). Fourth, hair provides some protection,
either simply by providing an additional protective layer (against
abrasion or sunburn, for example) or by taking on the form of
dangerous spines that deter predators (porcupines, spiny rats,
others). Mammals feed their newborn young with milk, a substance
rich in fats and protein that is produced by modified sweat glands
called mammary glands. These glands, which take a variety of
shapes, are usually located on the ventral surface of females along
paths that run from the chest region to the groin. They vary in
number from two (one right, one left, as in humans) to a dozen or
more. Other characteristics found in most mammals include highly
differentiated teeth; teeth are replaced just once during an
individual's life (this condition is called diphyodonty, and the
first set is called "milk teeth); a lower jaw made up of a single
bone, the dentary; four-chambered hearts, a secondary palate
separating air and food passages in the mouth; a muscular diaphragm
separating thoracic and abdominal cavities; highly developed brain;
endothermy and homeothermy; separate sexes with the sex of an
embryo being determined by the presence of a Y or 2 X chromosomes;
and internal fertilization. The Class Mammalia includes around 5000
species placed in 26 orders (systematists do not yet agree on the
exact number or on how some orders are related to others). Mammals
can be found in all continents and seas. In part because of their
high metabolic rates (associated with homeothermy and endothermy),
they often play an ecological role that seems disproportionately
large compared to their numerical abundance. Subclass Prototheria -
Not represented in southern Africa Order Monotremata -- Monotremes:
platypus and echidnas Subclass Metatheria (marsupials) - Not
represented in southern Africa Order Didelphimorphia Order
Paucituberculata Order Microbiotheria Order Dasyuromorphia Order
Peramelemorphia Order Notoryctemorphia Order Diprotodontia Subclass
Eutheria (placentals) Order Insectivora -- Insectivores: shrews,
moles, hedgehogs, tenrecs, etc. Order Macroscelidea -- elephant
shrews Order Scandentia -- tree shrews Order Dermoptera -- colugos
Order Chiroptera --bats Order Primates --primates Order Xenarthra
-- edentates; sloths, armadillos and anteaters Order Pholidota --
pangolins Order Lagomorpha -- rabbits and pikas Order Rodentia --
rodents Order Cetacea -- whales, dolphins, and porpoises Order
Carnivora -- carnivores Order Tubulidentata -- aardvark Order
Proboscidea -- elephants Order Hyracoidea -- hyraxes Order Sirenia
-- dugongs and manatees Order Perissodactyla -- horses, rhinos,
tapirs Order Artiodactyla -- antelope, giraffe, camels, pigs,
hippos, etc. Protheria- echidna & platypus Metatheria-
marsupial
Class Mammalia Protheria- echidna & platypus Metatheria-
marsupial Eutheria- true mammals A Guide to characteristics of
Class Mammalia The Class Mammalia is well represented in Southern
Africa. There are 293 species of land mammals and 37 species of
marine mammals in the Southern African subregion. That is 330 of
the around 5000 mammal species found on Earth! Class Mammalia --
all mammals share three characteristics not found in other animals:
3 middle ear bones; hair; and the production of milk by modified
sweat glands called mammary glands. Mammals hear sounds after they
are transmitted from the outside world to their inner ears by a
chain of three bones, the malleus, incus, and stapes. Two of these,
the malleus and incus, are derived from bones involved in jaw
articulation in most other vertebrates. Mammals have hair. Adults
of some species lose most of their hair, but hair is present at
least during some phase of the ontogeny of all species. Mammalian
hair, made of a protein called keratin, serves at least four
functions. First, it slows the exchange of heat with the
environment (insulation). Second, specialized hairs (whiskers or
"vibrissae") have a sensory function, letting the owner know when
it is in contact with an object in its external environment. These
hairs are often richly innervated and well-supplied with muscles
that control their position. Third, through their color and
pattern, hairs affect the appearance of a mammal. They may serve to
camouflage, to announce the presence of especially good defense
systems (for example, the conspicuous color pattern of a skunk is a
warning to predators), or to communicate social information (for
example, threats, such as the erect hair on the back of a wolf;
sex, such as the different colors of male and female capuchin
monkeys; presence of danger, such as the white underside of the
tail of a whitetailed deer). Fourth, hair provides some protection,
either simply by providing an additional protective layer (against
abrasion or sunburn, for example) or by taking on the form of
dangerous spines that deter predators (porcupines, spiny rats,
others). Mammals feed their newborn young with milk, a substance
rich in fats and protein that is produced by modified sweat glands
called mammary glands. These glands, which take a variety of
shapes, are usually located on the ventral surface of females along
paths that run from the chest region to the groin. They vary in
number from two (one right, one left, as in humans) to a dozen or
more. Other characteristics found in most mammals include highly
differentiated teeth; teeth are replaced just once during an
individual's life (this condition is called diphyodonty, and the
first set is called "milk teeth); a lower jaw made up of a single
bone, the dentary; four-chambered hearts, a secondary palate
separating air and food passages in the mouth; a muscular diaphragm
separating thoracic and abdominal cavities; highly developed brain;
endothermy and homeothermy; separate sexes with the sex of an
embryo being determined by the presence of a Y or 2 X chromosomes;
and internal fertilization. The Class Mammalia includes around 5000
species placed in 26 orders (systematists do not yet agree on the
exact number or on how some orders are related to others). Mammals
can be found in all continents and seas. In part because of their
high metabolic rates (associated with homeothermy and endothermy),
they often play an ecological role that seems disproportionately
large compared to their numerical abundance. Subclass Prototheria -
Not represented in southern Africa Order Monotremata -- Monotremes:
platypus and echidnas Subclass Metatheria (marsupials) - Not
represented in southern Africa Order Didelphimorphia Order
Paucituberculata Order Microbiotheria Order Dasyuromorphia Order
Peramelemorphia Order Notoryctemorphia Order Diprotodontia Subclass
Eutheria (placentals) Order Insectivora -- Insectivores: shrews,
moles, hedgehogs, tenrecs, etc. Order Macroscelidea -- elephant
shrews Order Scandentia -- tree shrews Order Dermoptera -- colugos
Order Chiroptera --bats Order Primates --primates Order Xenarthra
-- edentates; sloths, armadillos and anteaters Order Pholidota --
pangolins Order Lagomorpha -- rabbits and pikas Order Rodentia --
rodents Order Cetacea -- whales, dolphins, and porpoises Order
Carnivora -- carnivores Order Tubulidentata -- aardvark Order
Proboscidea -- elephants Order Hyracoidea -- hyraxes Order Sirenia
-- dugongs and manatees Order Perissodactyla -- horses, rhinos,
tapirs Order Artiodactyla -- antelope, giraffe, camels, pigs,
hippos, etc. Class Mammalia Whales & Dolphins Polar bear Sea
otter Seals & sealions manatee Dugong Evolution of the
mammalian jaw and ear bones Prototherians (Monotremes):
Egg-laying, aquatic predators on arthropods and worms Milk oozes
from the skin (no breasts). Hair present Ear bones shift from lower
jaw to skull during embryonic development. Subclass Prototheria
SKULL FEATURES: No teeth in living adults BUT fossil platys &
living neonates have, then lose. LOSS=apomorphy Subclass
Prototheria SKULL FEATURES: No teeth in living adults BUT fossil
platys & living neonates have, then lose. LOSS=apomorphy No
lacrimals (APOMORPHY) Subclass Prototheria SKULL FEATURES: No teeth
in living adults BUT fossil platys & living neonates have, then
lose. LOSS=apomorphy No lacrimals (APOMORPHY) Subclass Prototheria
SKULL FEATURES: No teeth in living adults BUT fossil platys &
living neonates have, then lose. LOSS=apomorphy No lacrimals
(APOMORPHY) Cranial sutures fused, indistinct (APOMORPHY) Subclass
Prototheria SKULL FEATURES: No teeth in living adults BUT fossil
platys & living neonates have, then lose. LOSS=apomorphy No
lacrimals (APOMORPHY) Cranial sutures fused, indistinct (APOMORPHY)
Jugal reduced or absent (APOMORPHY) Subclass Prototheria SKELETAL
FEATURES: Subclass Prototheria SKELETAL FEATURES: Epipubic bones
present, large (PLESIOMORPHY) Purpose?Used to think for puch
support, but makes less sense for taxa with backwards-facing
pouches. Epipubic bones present, large (PLESIOMORPHY)
Subclass Prototheria SKELETAL FEATURES: Epipubic bones present,
large (PLESIOMORPHY) Cervical ribs (PLESIOMORPHY) ribs on the
cervical (neck) vertebrae.Not found in any other living mammals.
Subclass Prototheria SKELETAL FEATURES: Epipubic bones present,
large (PLESIOMORPHY) Cervical ribs (PLESIOMORPHY) Horny, hollow
spur on inside of ankle (APOMORPHY) TWO ECHIDNAS (LEFT), PLATYPUS
(RIGHT) Subclass Prototheria SKELETAL FEATURES: Epipubic bones
present, large Horny, hollow spur on inside of ankle Pectoral
girdle with large precoracoids, coracoids, interclavicle All but
scapula and clavicle lost in all other mammals. Subclass
Prototheria SKELETAL FEATURES: Epipubic bones present, large
(PLESIOMORPHY) Cervical ribs (PLESIOMORPHY) Horny, hollow spur on
inside of ankle (APOMORPHY) Pectoral girdle with large
precoracoids, coracoids, interclavicle (PLESIOMORPHY) Skeleton
sprawling, reptilian (PLESIOMORPHY) BUT, good for swimming,
digging. Subclass Prototheria OTHER FEATURES: Pouch (echidnas only)
Subclass Prototheria OTHER FEATURES: Pouch (echidnas only) Testes
permanently abdominal (no scrotum) Subclass Prototheria OTHER
FEATURES: Pouch (echidnas only) Testes permanently abdominal (no
scrotum) Uteri fused Subclass Prototheria OTHER FEATURES: Pouch
(echidnas only) Testes permanently abdominal (no scrotum) Uteri
fused Leathery egg with nutrient-rich yolk Subclass Prototheria
OTHER FEATURES: Pouch (echidnas only) Testes permanently abdominal
(no scrotum) Uteri fused Leathery egg with nutrient-rich yolk
cloaca Subclass Prototheria OTHER FEATURES: Pouch (echidnas only)
Testes permanently abdominal (no scrotum) Uteri fused Leathery egg
with nutrient-rich yolk Rostrum lacks vibrissae, elongate cloaca
(but...) Endothermic, but low Tb and metabolic rates Subclass
Prototheria OTHER FEATURES: Pouch (echidnas only) Testes
permanently abdominal (no scrotum) Uteri fused Leathery egg with
nutrient-rich yolk Endothermic, but low Tb and metabolic rates
Electroreception (snout), including echidnas Fig Infra-class
Metatheria
Marsupials animals with pouches 7 Orders (18 families):
Didelphimorphia (American opossums)
Paucituberculata ("shrew" opossums) Microbiotheria (monito del
monte & extinct relatives) Dasyuromorphia (Australasian
carnivorous marsupials) Peramelemorphia (bandicoots and bilbies)
Notoryctemorphia (marsupial "moles") Diprotodontia (kangaroos,
wallabies, possums, koalas, gliders, wombats, etc) Metatheria
(Marsupials): Cretaceous-Recent
Pouched mammals. Born as gross little embryos. Crawl into pouch,
and develop. Today, they are most diverse on Australia and South
America. They share complex type of molar tooth shape with
Placental mammals. Metatheria are different because
Development Ecretory/reproductive systems Cranial differences
Epipubic bone Teeth Teeth P3/3, M4/4 Delayed development of
teeth
The milk teeth are represented by a single premolar in each jaw
Only replace one tooth postnatally Reproduction &
Development
Short gestation (8-43 days) Young born extremely small relative to
adult size Organs not completely developed Well-developed front
limbs for grasping fur Major investment during Lactation
Stays in pouch for 1 week - 1 year Leaves pouch at weight roughly
equivalent to birth weight of a similarly-sized placental Milk
changes composition during lactation Early: high protein, low fat
(for structural development) Later: low protein, high fat (for
rapid increase in mass) Marsupial vs. Placental
Character Marsupial state Placental state Diversity 6% of living
mammal species 94% of living mammal species size not as large
larger range of body sizes structural adaptations less diverse
flying (wings), marine (fins) Reproduction [Figs. 10.7] brief
gestation; semiembryonic young; body mass 1% of mother [Fig ]. Need
for precocious grasping forelimbs may constrain adaptability long
gestation period; young more developed at birth; body mass up to
50% of mother Placenta [Fig. 9.11] choriovitelline (usually)
chorioallantoic Lactation period [Fig. 10.7] long short Investment
of energy in motherhood lower, altricial young higher, reproduce
more rapidly (usually), precocial young Cerebral Cortex/ Braincase
smooth and complex, slow development, smaller volume (maybe) fast
development, greater volume (maybe) Behavioural plasticity uncommon
great range of behaviours Territoriality common and important
Antipredator behaviour not well developed highly developed,
particularly in herding animals; capable of sustained high speeds
Epipubic bones present absent Baculum [Fig. 9.3] present in most
Auditory bullae derived from alisphenoid bone varies, but not
alisphenoid primitive dental formula 5/4-1/1-3/3-4/4
3/3-1/1-4/4-3/3 Eutheria (Placentals): Cretaceous-Recent
Nourish their young internally with a placenta Placentals give
birth to offspring that are more "adult" like and independent.
Cretaceous ones were shrew-like in their ecology. Later placentals
are spectacularly diverse. Convergent Evolution Marsupial mammals
Eutherian mammals Marsupial
Fig Convergent Evolution Marsupial mammals Eutherian mammals
Marsupial mammals Eutherian mammals Plantigale Deer mouse Wombat
Woodchuck Marsupial mole Mole Wolverine Tasmanian devil Sugar
glider Flying squirrel Patagonian cavy Kangaroo