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Embrithopods - Arsinoitherium, early Oligocene 50 MYA - Rhino size - Paired horns - Fed on coarse-leafed swamp plants Proboscidea - Large grazers and browsers - Huge cheek teeth for grinding plants - Long columnar limbs - Large fatty pads on feet - Dispersal worldwide except Australia and Antarctica- Earliest well-known one: Pig-sized, trunkless African Moeritherium - 35 MYAMastodonts = Mammut - Mammut (nipple tooth), - Different teeth from living Elephantidae - 3 premolars and 3 molars - Progression in jaw back to front - Tusks in both sexes - Lower jaw tusks in many - Browser, open spruce forest 4-tusked mastodonts (Ampelodon, Platybelodon) - Short tusks and broad lower incisors - Used shovel to scrape up aquatic plants Family Elephantidae - 3 lineages from a rapid radiation out of Africa - Elephas: most diversity, two lines Europe/Africa and Asia- Mammuthus: widest geographic distribution - Loxodonta/Palaeoloxodon: smallest and largest “big” elephants - Large, columnar legs, elongated flexible trunks, tusks - Sister taxa: forest elephants, giant Palaeoloxodon - Sister taxa: asian elephants, mammoths Elephantidae molariform teeth - Occlusal surface: vertical plates alternating enamel with dentine- Serial replacement to compensate for wear (conveyor belt). Worn down as elephant ages - Many transverse ridges (loxodont) - Molars erupt, pushed as conveyor belt from back to front Elephantidae: Feet- Digits radiate out,- Digitigrade - Graviportal - Palm of hand (manus) and arch of foot (pes) supported by an elastic ball Elephantidae: Skull- High for muscles/ligaments - Leverage for tusks - Pneumatic sinuses - Brain cavity - Nasal passage Starting on Slide 24Asian Elephant whats being passed on is very small and diminutive tusks Loxodonta (Africa) vs Elephas (Asia)- Ear size - Number of nails on foot - Height at shoulder and hip - Convex or concave foreheard - Ribs: 21 pairs in Af. 20 in As.- Number of caudal (tail) vertebrae- Number of finger-like structures on end of trunk Loxodonta africana - Largest land mammal, 5-10+ tons - Feeds on coarse vegetation in open savanna and marshes - Low nutrient content food - Intake large - Hindgut fermenter - Feeds 70% of active time - Difficult to tame, never for work- Why? Plays into the strong connection of the Asian elephants and humans - theyhave basically been domesticated. African Elephants have never been domesticated - Mostly located in sub-Saharan Africa - Roman times: north to the Mediterranean and Syria - How? Hannibal -- used war elephants Loxodonta cyclotis- Smaller African forest elephant- Straight tusks, rounder ears - DNA: L. cyclotis and africana genetically different as lions and tigers, ½ as great as between L. africana and E. maximus - Closely related to giant extinct PaleoloxodonElephas maximus - Jungle to grassy plain- India and Southeast Asia, including: Sumatra, Borneo, Sri Lanka - Formerly in china to north to Yangtze river - They prefer grasses (different from african elephant), but they also consume bark, roots, leaves and stems of trees, vines and shrubs - Gregarious - Captured and trained for work African Elephant Ecology - Almost exclusively browsers, hindgut fermenters like horses and rabbits - Over 12 hours, one animal fed on 64 species of plants of 28 species - Grass is used only after suitable browse is gone - Devastation resulting from feeding, downed trees, uprooted, stripped bark - Role of migration, local devastation and regeneration - “Farm” saplings, fertilize soil, move on. Stands recover, elephants return Ecology and Society - Elephants have advanced social organisms - Society based on:- Closeness and intimacy among females - Power of the matriarch - Length of time associations endure Elephant population structure- 2-3 tiered hierarchy of sociality - Family unit; 10-20 females and young - Matriarch: largest, oldest, strongest - Rallies others and leads - Takes lead when confronting danger - Takes the rear position in retreat - Gradually replaced as she ages; sudden loss causes instability - Home range: 14-52 Km^2- Adolescent bulls play fight- At 13, form bachelor herds. Size determines dominance - Small bulls may form coalitions to dominate a mid-sized bull - Large, adult bulls are solitary, maintain small home range along paths to water holes - Kinship group: ensemble of family groups that remain nearby, show personal familiarity, probably arise from splitting family groups - Clan: 100-250 individuals that aggregate together during mass migration Cooperation and altruism - Calves of both sexes are treated equally - Nurse any lactating female - Adolescent cows: “aunts” - Family members assist, defend one another African elephant communication - Visual signals, vocalizations and scent - Hostility shown by series of postures and sounds - Lowest: “standing tall” head lifted, peer over tusks, ears cocked forward - Middle: move toward enemy crack of ears, extend trunk forward, trunk swish and trumpet - Highest: full charge, ears flapping, trunk held high, trumpet loudly Hearing and vocalizations - Hearing as acute as humans - Trained Asian elephants recognize up to 24 verbal commands - Vocalizations include growls, trumpets, squeals, shrieks - Infrasound (14-24 Hz), not audible to humans but can be sensed as air pressure vibrations - Probably picked up by the elephant skeleton, foot padsChemical Communication - Very keen sense of smell- Sense danger (man, lion etc.) - Bulls check sexual condition of cows - Family group members track one another - Temporal gland- Produces a strong-smelling secretion - Begins at 12-15 years (sexual maturity) - Maximum release when excited or under stress - African: both sexes rub secretion on trees - Asian: only males produce secretions Musth- Male society regulated by smell: - Socially immature males: release honey-like odors to avoid conflict with adult males - Older musth males: malodorous combinations deter young males Courtship and Mating- Females advertise estrus by odor; a mature bull in a cow herd indicates a cow is in estrus - Adult male and estrus female form a consort - Courtship includes touching with trunks - During mounting, cows and juveniles circle couple - Gestation 22 months, nursed for 6 months, calf is weaned at 12 months - Testes are in the same position as ovaries - Consistency of temp in body could be beneficial -

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UWL BIO 488 - Lecture 12

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