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