Mammals. Mammalia. Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class Mammalia. Class Mammalia Major Characteristics. Endothermy Hair Completely divided, 4-chambered heart Milk Single jawbone Specialized teeth Amniotes 3 inner ear bones. Key characteristics.
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Mammalia • Kingdom: Animalia • Phylum: Chordata • Subphylum: Vertebrata • Class Mammalia
Class Mammalia Major Characteristics • Endothermy • Hair • Completely divided, 4-chambered heart • Milk • Single jawbone • Specialized teeth • Amniotes • 3 inner ear bones
Key characteristics • Endothermy-Mammals produce body heat internally through metabolism. • Hair- All mammals have hair. The main function of hair is to insulate the body against heat loss. • Completely Divided Heart- Mammals have a four chambered heart with two completely separate ventricles.
Key Characteristics Cont. • Milk- Female mammals produce milk from their mammary glands. They do this to feed their offspring. • Single Jawbone- This helps identify mammalian fossils. (Reptiles have several jawbones.) • Specialized Teeth-Front teeth are used for biting, cutting, or seizing prey. Side teeth are for crushing, grinding, or slicing.
Amniotic • Eggs developed with a set of membranes (placenta) to protect them in a terrestrial environment • they prevent dessication, in other words, they ensure that the embryos do not dry-out • they enable gas exchange between the embryo and its environment as its develops • they allow waste materials to be disposed of while the embryo develops • they enable the embryo to receives the nutrition it needs to develop
Mammal’s • 5,000 species • 26 orders
Groups • Order Monatremata: duckbill platypuses, spiny anteaters • Order Marsupialia: opossums, kangaroos, koalas, wallabies • Placental mammals (18 orders)
Order Monetremata • In this order the animal lays eggs • They include many of the mammals that people consider as abstract or weird. • Only three species exist in this order. • The species only live in Australia and New Guinea.
Order Marsupialia • 280 species exsist within this order. • Australia, New Guinea, & The Americas is where these animals populate. • The incubation period for these animals is very short so many babies are born underdeveloped in a shorter period of time, e g. kangaroo joeys are born after a 4-5 week gestation.
Placental Mammals • 95 percent of mammals are placental mammals. • There are 18 different orders within the group of placental mammals. • The incubation period of these animals is longer than that of the marsupials
Placental mammals • Primates: Monkeys, Lemurs, Gibbons, Orangutans, Gorillas, Chimpanzees, Humans • Insectivora: Moles and Shrew • Chiroptera: Bats • Enentata: Armadillos, Sloth, Anteaters • Pholidota: Pangolins • Rodentia: Squirrels, Woodchucks, Mice Rats, Muskrats, Beavers • Lagomorpha: Rabbits, Hares, Pikas • Carnivora: Whales, Porpoises, Dolphins • Sirenia: Sea Cows, Dugongs, Manatees • Proboscidea: Elephants • Pinnipedia: Seals, Sea Lion, Walruses • Perissodactyla: Rhino’s, Horses, Zebras • Artiodactyls: Hippos, Camels, Deer, Giraffes, Cattle, Sheep, Goats • Macroscelidea: Elephant Shrew • Scandentia: Tree shrew • Hyracoidea: Hyraxes • Dermoptera: Flying lemurs • Tubulidentata: Aardvark
Trophic categories Scientists place placental mammals in 4 trophic categories based on what they eat: • Instectivore • Eat insects and other small invertebrates • Moles, shrews, anteaters • Herbivores • Eat vegetation (primary consumers) • Rabbits, deer, horses • Carnivores • Feed on herbivores (secondary/tertiary consumers) • Wolves, lynx • Omnivores • Feed on both plants and animals • Raccoons, primates
Evolutionary history:Synapsids • “mammal-like reptiles” • Diverged from a common ancestor with reptiles • Have a very distinct skull with a hole in the jaw for attachment of muscles of the jaw
Reproduction • Monotreme mothers typically one or two eggs and incubates them with her body heat. • Newborn marsupials emerge form their mothers uterus when they are ready. Its growth and development continues in its mothers pouch. • Placental mammals: Once the egg is fertilized it attaches to its mothers uterus and is nourished by the placenta.
Remember, Synapsids gave rise to mammals and mammal-like reptiles, the first of which were the THERASPIDS:
Pentadactyl limbs • Pentadactyl (pent = 5, dactyl = finger) • Type of adaptive radiation in mammals • The pentadactyl limb has become adapted to different environmental conditions and modes of life
Convergent evolution • Structures of unrelated species can evolve to look alike because the structures are adapted to a similar function. These are called analagous structures • They differ from each other in their microscopic details and their embryonic development • The process by which they evolve to resemble each other is called convergent evolution