Ch 34 - Vertebrates (1 slide per page)-1

31 campbell et al 78 ectotherms animals that derive

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Unformatted text preview: es between non-feathered dinosaurs and birds Archaeopteryx lithographica - Feathers probably for camouflage and insulation - Hollow bones probably for speed and agility - Mounting evidence that many avian and nonavian dinosaurs were endothermic (like modern birds) Figure 34.31 (Campbell et al) 78 ECTOTHERMS: Animals that derive body heat from the environment e.g. fish, amphibians, reptiles ENDOTHERMS: Animals that generate body heat by metabolism e.g. birds & other related dinosaurs, mammals Endothermy evolved convergently in birds and mammals 79 The Birds Approximately 10,000 species (the most diverse tetrapods) • Forelimbs modified to wings • Light bones, no teeth • 4-chambered heart; • Endothermic • Most widely spread group of amniotes 80 The Mammals Limbs w/ digits 81 The Mammals Approximately 5,400 species • Arose during Jurassic period (150-200 Mya) • Radiated after Cretaceous extinction Defining traits: • Mammary glands • Hair • 4-chambered heart; • Endothermic • Dentary-squamosal jaw joint • 3 inner ear bones: – 2 evolved from jaw joint • Divided into 3 groups primarily based on reproductive differences – Monotremes – Marsupials – Placentals 82 Mammals Monotremes • Only mammals to lay eggs • Produce milk from pores • No nipples - suck milk from mother’s fur Echidna • Restricted to Australasia • (Australia + New Guinea) Platypus 83 Mammals Marsupials • Live birth w/ very short gestation (embryo completes development in pouch) • Milk from nipples • Rudimentary placenta • Embryo and mother’s circulatory system not joined Kangaroos, wallabies, opossums, koalas etc. Mostly: Australasia & South America (1 N. American species Didelphis virginianai) 84 Mammals Eutherians • Complex placenta • Complete embryonic development in uterus 85 Mammals Eutherians • Complete embryonic development in uterus • Complex placenta In marsupials, nutrients from mother’s blood go into yolk sac which nourishes embryo Vaginal segments of marsupial combine to form larger uterus for embryonic development in eutherians In eutherians, nutrients from mother’s blood go directly into embryo’s blood
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This note was uploaded on 02/12/2014 for the course BIOLOGY 2011 taught by Professor Woo during the Fall '10 term at University of Central Florida.

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