Mammalia. Mammal Evolution Mammals are believed to have evolved from Reptiles during the late...
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Transcript of Mammalia. Mammal Evolution Mammals are believed to have evolved from Reptiles during the late...
![Page 1: Mammalia. Mammal Evolution Mammals are believed to have evolved from Reptiles during the late Jurassic period.](https://reader035.fdocuments.in/reader035/viewer/2022062308/56649dc45503460f94ab6974/html5/thumbnails/1.jpg)
MammaliaMammalia
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Mammal EvolutionMammal Evolution• Mammals are believed to have
evolved from Reptiles during the late Jurassic period
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Mammal EvolutionMammal Evolution• The first true mammal was a small,
shrew-like organism that coexisted with Dinosaurs– Ex. Hadrocodium fossil found in
Northern China in 2002
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Mammal EvolutionMammal Evolution
• Mammal’s inner-ear bones probably evolved from modified ancestral reptile jaw bones
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3 Major Reproductive Categories
• Monotremes– Egg-laying mammals (Ex. Echidna +
Platypus)
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3 Major Reproductive Categories
• Marsupials– Embryos born very early and nurse
from inside mother’s pouch (Ex. Kangaroo, Koala)
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3 Major Reproductive 3 Major Reproductive CategoriesCategories
• Placentals– Embryos develop inside the womb,
receiving nutrients and O2 from the mother via the Placenta
– Newborns fed milk from mammary glands.
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Mammal Mammal CharacteristicsCharacteristics
• Characterized by hair and mammary glands
• Whales have very little hair
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Mammal Mammal CharacteristicsCharacteristics
• Mammalian brains are more developed and specialized (cephalized) than any other class of animals
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Mammal Mammal CharacteristicsCharacteristics
• All mammals have special sweat glands that are modified for producing milk, called Mammary glands
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Mammal Mammal CharacteristicsCharacteristics
• Mammals are Heterodontic– Teeth are
differentiated– Used for biting,
grinding, tearing and crushing
– Ex. Incisors, molars, canines, etc.
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Mammal Orders • There are 19 orders of mammals• We will look at the characteristics of
14 of them
• Order: Monotremata– Lay Eggs (Ex. Echidna, Platypus)
• Order: Marsupiala– Young grow in pouch (Ex. Koala)
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Order: Insectivora
• Small pointed teeth, adapted mainly for eating insects– Ex. Moles, Shrews, Hedgehogs
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Order: Rodentia• Nearly 50% of mammals are
rodents• Have no canine teeth, but two very
larger incisors• Almost all are herbivores
– Ex. Mice, Squirrels, Beavers
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Order: Edentata• Have no teeth
– Ex. Armadillos, Sloths, Anteaters
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Order: Carnivora• Very diverse group,• Meat eaters• Canine teeth highly developed
– Ex. Wolves, Bears, Raccoons, Otters, Skunks, Mongoose, Cats
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Order: Serenia• Aquatic mammals that breathe
through their mouth and nose• Herbivores
– Ex. Manatees and Dugongs
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Order: Chiroptera• Forelimbs adapted for flight• May find prey by echolocation
– Ex. Insectivorous Bats, Old World Fruit Bats
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Order: Lagomorpha
• Large incisor teeth• Hindlimbs larger than forelimbs
– Ex. Rabbits and Pikas
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Order: Cetacea• Fully aquatic mammals• Vestigial pelvic bones• Evolved from a wolf/bear-like land
mammal
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Order: Cetacea• Highly developed brain• Have a dorsal blow-hole
– Ex. Toothed Whales, Baleen Whales
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Order: Proboscidea
• Nose and top lip are highly enlarged into a muscular trunk for grasping items– Ex. Elephants
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Order: Primata• Highly developed brains• Often bipedal
– Ex. Lemurs, Monkeys, Apes, Humans
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Order: PrimataOrder: Primata
• Humans are relatively new primates
• We appear to share a recent common ancestor with chimpanzees
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Order: Artiodactyla• Hooves with even-numbered toes• Many of them are ruminants with a 4-
chambered stomach– Ex. Deer, Giraffe, Cattle, Pig, Camel, Hippo
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Order: Perissodactyla• Have odd-numbered toes
– Ex. Horses, Tapirs, Rhinoceroses