Practicle #7 Flashcards
Mammal evolution
Synapsides (mammal-like reptiles) split from sauropsids (reptiles+birds) –> small, shrew-like mammals formed –> mass dinosaur extinction –> mammals filled roles of extinct animals
Mammalia apomorphies
- secondary bony palate
- muscular, thoracic diaphragm
- 4 chambered heart
- endothermy
- single bone in lower jaw
- heterodont dentition
- middle ear (3 bones)
- mammary glands
- hair
- viviparous
- cloaca lsot
- expanded gray matter in brain
- ear flap well developed
- nipples/teats
- males with external gonads
- chorioallantoic placenta
Mammals
- massive size variation
- mostly terrestrial
- one airborne
- occupy all continent, oceans, islands
Heterodont dentition
Many types of teeth in one mouth, allows for better chewing, aids digestion.
- canines
- incisors
- premolars
- molars
Secondary bony palate
Sperates mouth from nasal cavity, allows for breathing while we chew.
Middle ear
Composed of 3 bones (stapes, malleus, incus), allows for better hearing, sensitiviy to more bandwidth.
4 chambered heart
Left aortic arch only, separation of pulmonary and systemic circuits.
Muscular diaphragm
Helps with breathing, increased volume of thoracic cavity.
Mammary glands
Modified sweat glands that provide young with nourishing milk.
Endothermy
“Warm blooded,” allows animals to remain active in cold condition.
Hair
Used for insulation, sensation, camouflage, defense.
Monotremes
Platypus, echinda.
- adults lack teeth
- oviparous
- lack nipples
- have cloaca
Theria
Marsupialia, eutheria/placentalia.
- viviparous (embryos develop in uterus, nourished in placenta, birthed live)
- large cerebrums
- anus and urethral opening
- have piannae
- external gonads and/or nipples
Marsupials
- Choriovitelline placenta
- further development occurs in marsupium (pouch)
- short gestation periods
Eutherians
- chorioallantoic placenta
- long gestation periods
- corpus callosum = connection between cerebral lobes
Afrotheria
Hyraxes, sirenians, elephants, aardvarks, elephant shrews, hedgehods, etc.
Xenarthra
Armadillos, tree sloths, anteaters.
- reduced dentition
- low metabolic rates
- 1 color vision
Boreoeutheria
Most mammals…
Pangolins, moles and shrews, carnivora, primates, ciroptera, rodents, lagomorphs, perissodactyle, artiodactyla
Euliptyphla
Moles, shrews.
Carnivora
Dogs, cats, bears.
- shearing teeth
- not all carnivores
- carnassials
- walk on toes
Primates
- tropical/arboreal
- opposable digits
- big brains
- good eyesight
- herbivorous/omnivorous
Chiroptera
Bats.
- eat insects, fruit, pollinate
- powered flight
- echolocation
Rodentia
Largest mammal group.
- mostly herbivores
- upper and lower pair of every-growing, self-sharpening incisors
Lagomorpha
Rabbits and pika.
- herbivores
- elongate ears and hindlimbs
- two sets of upper incisors
Perissodactyla
Horses, rhinos, tapirs.
- 1 or 3 toed hooves
Artiodactyla
Giraffes, deer, moose.
- various types of head ornamentation
1) horns = bone core with permanent keratin sheath
2) antlers = bones that are shed annually
3) proghorns = bone core with hair sheath, shed annually
4) ossicones = permanent skin covered bone growths
Cetaceans
Whales and dolphins.
- lost hind limbs
- nostrils on to of head
- echolocation
- toothed or baleen
