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48 Cards in this Set
- Front
- Back
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Origins of Mammals
Non-mammalian synapsids |
Dominate from late Carboniferous to Triassic (extinct in Jurassic)
trend: large to small skins not scaled: hide w/ glands "Pelycosaurs" "Therasids" "Cynodonts" |
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Origins of Mammals
Non-mammalian synapsids "Pelycosaurs" |
Morphology: sails, prostrate limb posture, large girdles, ribs on most precaudal vertebrae
Metabolism: likely ectotherms |
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Origins of Mammals
Non-mammalian synapsids "Therasids" |
Morphology: Large temporal fossa, longer canines, wider flatter snout, lighter (longer) limbs, and girdles (held under body)
Metabolism: hair & endothermy |
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Origins of Mammals
Non-mammalian synapsids "Cynodonts" |
Morphology: bowed zygomatic (temporal) arch, secondary palate, complex postcanine teeth, no lumber ribs, calaneal heel
Metabolism: most certainly endothermic give rise to modern mammalia (late Triassic) |
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Origins of Mammals
Mesozoic Mammalian Radiation (2/3 history) Key Mammalian Features |
Dentary-squamosal jaw joint
Three inner ear bones (incus, malleus, stapes) Lactation & suckling precise tooth occlusion: for mastication illium: rod shaped for bounding gait |
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Origins of Mammals
Mesozoic Mammalian Radiation Early Mesozoic forms |
small nocturnal insectivores
ex. Morganucodon |
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Origins of Mammals
Mesozoic Mammalian Radiation Prototheria (monotremes) |
early as Jurassic
probably oviparous like modern forms primitive girdle design and posture |
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Origins of Mammals
Mesozoic Mammalian Radiation Theria (placentals & marsupials) |
arise in Cretaceous
Tribosphenic molar design, may proceed true therians viviparity= narrower pelvis than oviparous, small young fed w/ milk (matrophy) Eutheria & metatheria= diverged in Cretaceous |
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Origins of Mammals
Evolution of Mammalian Jaw and Ear |
Dentary-squamosal jaw joint
three auditory ossicles increased strength conflict w/ hearing brain dimensions |
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Origins of Mammals
Evolution of Mammalian Jaw and Ear "Pelycosaurs" |
stapes= only ossicle (general tetrapod condition)
jaw articulation: articular & quadrate Lower jaw: dentary & postdentaries (articular, angular, ect.) |
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Origins of Mammals
Evolution of Mammalian Jaw and Ear Therapsids & Cynodonts |
postdentaries & quadrate: reduced & loose
tympanic membrane on angular (ear drum) |
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Origins of Mammals
Evolution of Mammalian Jaw and Ear Mammalia |
Jaw joint: dentary-squamosal
Postdentary bones: lost or inner ear bones angular: tympanic: supports tympanic membrane articular: malleus: outer most ossicle quadrate: incus: middle ossicle (contacts stapes) |
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Origins of Mammals
Mammalian Biogeography |
Jurassic: Pangaea breaks up
Major Faunal provinces form: Holarctic: N. Hemisphere: mostly placentals Old World Tropic: Africa & S.E. Asia: mostly placentals New World Tropic: S.America: placentals & marsupials Australian: mostly placentals & marsupials |
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Origins of Mammals
Mammalian Biogeography Cenozoic |
drier & cooler (ice caps & ice ages)
evolution of modern orders (explosion) isolation & recombine faunas within/among provinces, ex. Great American Interchange (2.5 MYA) Occasional large extinction events, ex. Late Pleistocene (10000 YA), irish elks, mammoths, ground sloths |
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Features of Mammals - Locomotion
Girdles Pectoral Monotremes |
typical "reptilian" condition, large ventral parts (ex. coracoids, interclavicles)
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Features of Mammals - Locomotion
Girdles Pelvic assemblage |
long rod shaped illium
epipubic bones: monotremes & marsupials, placentals: lost crurotarsal ankle joint w/ astragulus, calcaneal heal: lever arm for gastrocnemius |
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Features of Mammals - Locomotion
Terrestrial Locomotion Scansorial |
terrestrial/arboreal mixture (primitive)
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Features of Mammals - Locomotion
Terrestrial Locomotion Cursorial |
running (efficient at all speeds)
maximize stride length reduce foot contact digitigrade: foot plants on digits (ex. dogs) unguligrade: plants on hooves of a few toes |
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Features of Mammals - Locomotion
Terrestrial Locomotion Fossorial |
digging (maximize limb strength)
plantigrade: flat footed posture short limbs w/ large leverage |
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Features of Mammals - Locomotion
Other Locomotion Swimming |
reduced appendage length
pinnipeds, cetaceans: pelvic reduced/absent beavers, otters= pelvic kicking |
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Features of Mammals - Locomotion
Other Locomotion Flight |
extended forelimbs & membranes
powered: likely evolved only once (bats) gliding: multiple convergent forms |
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Features of Mammals - Locomotion
Other Locomotion Hoping |
rodents, lagomorphs, marsupials
hindlimbs: powerful with large tail (balance) forelimbs: often reduced, but dexterous |
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Features of Mammals - Locomotion
Other Locomotion Brachiating |
swinging by arms (some primates)
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Feeding of Mammals
Senses & feeding Sensory Tendencies Sight |
limited spectral sensitivity but excellent night vision
rods: present & extensive in most mammals tapetum lucidum: reflective layer behind retina |
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Feeding of Mammals
Senses & feeding Sensory Tendencies Hearing & smell |
sound: from infrasound to ultrasound, ex. elephants, bats, dolphins
smell: important in social communication scent glands: in most mammals |
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Feeding of Mammals
Senses & feeding Sensory Tendencies Sight cones |
cone monochromats: pinnipeds & cetaceans
cone dichromats: most mammals cone trichromats: some primates & a few marsupials |
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Feeding of Mammals
Feeding Adaptations Carnivores |
jaw joint even w/ tooth row
temporalis muscle large: gripping with canines occipital region: high with extensive neck musculature carnassials: sheering teeth of carnivores |
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Feeding of Mammals
Feeding Adaptations Herbivores |
jaw joint higher than tooth row
masseters large: grinding occipital region: smaller & lower canines: lost, but post orbital bar retained diastema: gap between cheek teeth & incisors, elongated snout |
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Feeding of Mammals
Feeding Adaptations Omnivores & frugivores |
less specialized design
bunodont molars: square 4-cusp teeth (rounded) ex. primates |
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Feeding of Mammals
Feeding Adaptations Diphyodonty |
only replace front teeth once
problem with durability: esp. in herbivores molars: cusps become lophs (ex. lophodont), creates grinding surface incisors: grow continuously in rabbits/rodents, enamel on front only: self-sharpening |
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Feeding of Mammals
Feeding Adaptations Other specializations Ant-eating mammals |
long jaws
reduced teeth long tongues |
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Feeding of Mammals
Feeding Adaptations Other specializations Cateceans |
long jaws w/ simple teeth
baleen: keratin |
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Feeding of Mammals
Feeding Adaptations Other specializations monotremes |
no adult teeth
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Feeding of Mammals
Feeding Adaptations Other specializations deer |
loss of top incisors (hard pad instead)
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Feeding of Mammals
Feeding Adaptations Other specializations tusks |
elephants & narwhals: incisors
walrus: canines |
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Feeding of Mammals
Mammalian Swallowing & Suckling Two tight seals |
1. tongue against soft palate
2. epiglottis & back of soft palette allows food to pass trachea into esophagus lost in adult humans (speech) |
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Feeding of Mammals
Mammalian Swallowing & Suckling Suckling in infants |
seal 1 & tongue depress: draw milk into mouth
seal 2: allows breathing & suckling simultaneously facial muscles: originally evolved for suckling |
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Feeding of Mammals
Reproduction |
matrophy & parental care = universal
extensive sociality: in mating, parental care, feeding, defense, ect. |
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Feeding of Mammals
Reproduction Mammae & lactation |
All female mammal species lactate
mammary glands: milk producing glands, only entirely absent in male marsupials nipples or teats (w/ cistern): only present in therians mammary hairs: monotremes |
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Feeding of Mammals
Reproduction Mammae & lactation Milk |
fats, carbos, protein
variable amoung species & over time asynchronous: some marsupials (kangaroos) diff milk at same time |
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Feeding of Mammals
Reproduction Gestation Trophoblast |
additional outer layer of embryonic cells
for nutrition & pregnancy signaling |
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Feeding of Mammals
Reproduction Gestation Endometrium |
glandular uterine lining
supplies nutrients to embryo |
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Feeding of Mammals
Reproduction Gestation Corpus Luteum |
secretes progesterone (remnant of follicle)
what's the role of progesterone signals other hormones to extend & maintain pregnancy |
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Feeding of Mammals
Reproduction Gestation Monotremes |
lays eggs
reproductive tract: primitive amniote condition matrotropy: insufficient yolk to sustain young leathery shell: cut w/ egg tooth |
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Feeding of Mammals
Reproduction Gestation Therians Eutherians |
chorioallantoic placentae
uterus: fused oviducts in mid line corpus luteum: retained > 1 estrus cycle young retained > 1 cycle lactation time: usually less then gestation |
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Feeding of Mammals
Reproduction Gestation Therians Metatherians (part 1) |
yolk sack placentae
lateral vaginae: sperm transport only male penis often bifurcate as well pseudovaginal canal: forms parturition corpus luteum: retained < 1 estrus cycle, highly altricial birth |
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Feeding of Mammals
Reproduction Gestation Therians Metatherians (part 2) |
most have pouches encasing nipples, often involves specialized birth positioning
lactation time: usually more than gestation unsuitable for fully aquatic life or flight |
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Mammals
locomotion pectoral girdle Therians |
reduced ventral elements, expanded scapula, muscular (scapular) sling: shock absorption & flexibility
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