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 http://palaeo.gly.bris.ac.uk/palaeofiles/marsupials/female%20repro.jpg In eutherians, nutrients from mother’s blood go directly into embryo’s blood http://www.siumed.edu/~dking2/erg/images/placenta.jpg...
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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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