Biology 103 Week 3 Notes
Biology 103 Week 3 Notes BIO 103-002
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This 3 page Class Notes was uploaded by Lucas Kinsey on Friday September 16, 2016. The Class Notes belongs to BIO 103-002 at George Mason University taught by Gwendolyne Fondufe in Fall 2016. Since its upload, it has received 61 views. For similar materials see Introductory Biology I in Biology at George Mason University.
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Date Created: 09/16/16
Lucas Kinsey Biology 103 Week 3 Notes Chapter 19 The evolution of Vertebrate Diversity Craniates: All chordates that have a head - First evolutionary step of the chordate lineage Vertebrates: Next evolutionary step of a backbone and a skull Bones are mostly non-living material, but grow with the body because living cells secrete this material Tetrapods: Jawed and limbed (two pairs of limbs) were the first vertebrates on land - Amniotes: tetrapods that lay terrestrial eggs Hagfishes and lampreys are the most primitive surviving craniates - Lampreys are considered vertebrates because of its notochord Jawed vertebrates occurred around 440 million years ago One hypothesis says that hinged jaws evolved by modification of skeletal supports of the gill slits in primitive fishes Chondrichthyans: sharks and rays that have flexible cartilage skeletons Lateral Line System: a row of sensory organs running along each side that are sensitive to changes in water pressure and can detect vibrations cause by nearby swimming in the water Ray-finned fished: - Ex: Tuna, trout, goldfish, ect… - Skeleton made of bone Operculum: A protective flap that covers gills Ray-finned fishes are the most diverse group of vertebrates with over 27,000 species Land vertebrates developed during the Devonian period Ichthystega: believed to be one of the first fish to be able to move on land First tetrapods were not fish with lungs that gradually grew legs, but rather the neck and limbs grew first and they would just raise their heads out of water for air Amphibians: Tetrapods that were the first official terrestrial species of vertebrates Amphibians are lowering in numbers due to habitat loss, climate change, and pathogenic fungi Carboniferous Period was known as the age of the amphibians Reptiles, birds, and and few mammals are amniotes Amniotic Egg: Reptilian egg with extra embryotic membranes - Amnion: Fluid filled sac surrounding the embryo - Yolk Sac: Contains a rich store of nutrients for the embryo - Chorion and Allantois: Enable the embryo to obtain oxygen from the air Ectothermic: Animals that absorb external heat rather than generate much of their own Birds descended from reptiles Features that help birds fly: - No teeth - Only a few small vertebrae - Feathers that have hollow shafts - Bones have honeycombed structure Endothermic: when animals use heat generated by their metabolism to maintain a warm, steady body temperature Birds have a highly efficient circulatory system to support their high metabolisms Distinguishing traits of mammals are hair and milk glands 3 Major lineages of mammals: 1. Monotremes – Egg-laying mammals 2. Marsupials – Mammals with a pouch for young 3. Lutherans – Mammals that bear fully developed live young Placenta: a structure in which nutrients from the mother’s blood diffuse into the embryo’s blood Anthropoids: Have fully opposable thumbs Paleoanthropology: the study of human origins and evolution Hominins: Species that are more closely related to humans than to chimps The brain grew throughout evolution Homo Neanderthals: Most recent ancestor of Homo Sapiens All humans have ancestors that originated in Africa - Increase in population probably cause the species Homo Sapiens to expand to other parts of the world Human skin reflects adaptations to varying amounts of sunlight - The lighter the skin cells the less melanin there is in the skin
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