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BIOL211 Zoology Key Concepts.docx

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University of Waterloo
BIOL 211
Bill Taylor

CONCEPTS Are dinosaurs endothermic? Endothermic - no growth rings in bones - active running animal limb anatomy - fewer dinosaurs (predators) than prey - stable isotopic composition is consistent with high body temperatures Ectothermic - no living reptiles are endothermic - no elaborate nasal bones to conserve moisture and heat Mass Extinctions of - end of Cretaceous Period (65 mybp) Vertebrates  most recent mass extinction - at least 5 mass extinctions during vertebrate evolution - most severe was end of Permian era (250 mybp)  due to volcanism and wildfires Time Periods Metatherian versus Eutherian - eutherians are placental mammals  in uterus (i.e. reproduction shrew) - metathera are marsupial mammals  in pouch (i.e. opossum) Mesozoic Continents - marsupials originated in North America, invaded Eurasia, South America, Antarctica, and Australia - Eutherians originated in Eurasia and displaced marsupials – invated South America late and never made it to Antarctica / Australia until introduced there by humans - One marsupial (the opossum) recently reached Ontario after reinvading North America from South America Microlecithal Eggs Zygote to Blastula - Radial, complete, (example: Amphioxus) equal cleavages - Leads to hollow space (blastocoel) Gastrulation - invagination, creates endoderm and ectoderm with mesoderm in middle (on dorsal part of endoderm) Neurulation - notochord will develop at mesoderm - notochord induces formation of neural tube - embryo is now a neurula Mesolecithal Eggs Zygote to - complete, markedly (example: Amphibian) Blastula unequal divisions - larger cells on one side (vegetal pole), blastocoel towards animal pole - more yolk, bastula is several cells thick, small blastocoel Gastrulation - gastrocoel highly modified to accommodate all the yolk - splitting of coelom instead of evagination Neurulation - mesoderm formation starts dorsally at notochord and is partitioned into 3 sections on each side Macrolecithal Eggs Zygote to Blastula - incomplete cleavage; (Example: Reptiles) eventually lead to patch of flat cells called a germinal disk - blastula = layer of cells on a mass of yolk Gastrulation - separation of germinal disk into two layers, rather than process of involution Neurulation - neural tube forms ahead of primitive streak, and above notochord Eutherians (Microlecithal) Gastrulation - endoderm cells migrate from ectoderm, mesoderm arises at primitive streak Neurulation - formation of primitive streak and mesoderm, including notochord - similar to that of birds/ reptiles Extraembryonic - in an amniotic membranes cavity - yolk sac is vestigial, chorion interacts with uterine wall to make placenta CHAPTER 7 Ectoderm - neural crests form pharyngeal cartilage/ bone/ teeth, sensory nerves, acoustic and lateral line system - neural tube will form central nervous system - ectoderm will produce epidermis and derivatives Mesoderm - dermatome  outer layer of epimere; produces dermis - myotome  inner layer of epimere; forms trunk muscles. Innermost part becomes sclerotome  surrounds notochord and becomes vertebrae - mesomere  produces excretory and reproductive systems - hypomere  makes serous lining of peritoneal cavity, mesenteries, and gut muscles - mesechyme  mobile cell mass that leaves mesoderm Endoderm - will form inner lay of gut, organs of gut, and germ cells Fate of Extra-Embryonic Structures - mesoderm splits into coelomic space (coelom) - allantois  evaginates from embryo’s gut; respiratory organ, reservoir for waste in embryo - amnion  mesoderm - ectoderm  ectoderm - amniotic cavity  space where embryo resides - connection to yolk becomes a yolk stalk as embryo grows (and yolk gets smaller) CHAPTER 8 Integument Functions - protection - water balance - reserve food storage - heat regulation - sensory - excretion - secretion (lots of glands) - respiration - locomotion - communication - reproduction Vertebrate Integument - epidermis produces mucus in fish and amphibians, and keratin in tetrapods - glands are from epidermis but can penetrate into dermis - melanophores  brown/black pigment cells in epidermis containing melanin - chromatophores  more diverse in pigmentation than melanophores - dermis may contain blood vessels, nerve endings, fat bodies, collagen, elastic fibres, chromatophores, and bone Fish Integument - epidermis  thin, well-supplied (teleosts) with unicellular mucous glands, slimy - scales deeper (in dermis, not epidermis) – dermis produces bone; epidermis does not Amphibian Integument - like fish, no scales, poison glands common - moist and mucous covered - poison glands are much larger Reptile Integument - no mucous glands in amniotes, but possibly scent glands - scales are epidermal, not dermal (keratin instead of bone)  not homologous with fish scales - scutes  larger scales on ventral surface of snakes - osteoderms  dermal bones under scutes (not always present) Bird Integument - - thinly keratinized skin - reptile-like keratin scales on legs, feathers thought to be derived from keratin - have claws and friction pads on feet - keratin beaks, uropygial gland under tail for grooming feathers - feather produced from
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