Chapter 26ANIMALS II

Chapter 26ANIMALS II - Chapter 26 I Chapter 26 I Animal...

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Unformatted text preview: Chapter 26 I Chapter 26 I Animal Evolution – The Chordates and Vertebrates No one was around to witness the Impacts, Issues: Interpreting and Misinterpreting the Past transitions in the history of life Fossils allow us glimpses into the past, giving us opportunities to improve our understanding of the story of life on earth and own origins Something Old, Something Old, Something New Every animal is a combination of traits Some traits are conserved from remote ancestors Other traits are unique to its branch of the family tree The Chordates arose from an ancient Deuterostome Deuterostomes Protostomes Coelomate ancestry Bilateral symmetry Radial symmetry Multicelled ancestry Chordate Groups Chordate Groups Hemichordates­Acorn worms (the transition to the true chordates) Urochordata ­Salps and Tunicates Cephalochordata ­Lancelets Craniates­Fishes, amphibians, reptiles, birds, mammals Chordate Features Chordate Features Deuterostomes: the mouth comes from the 2 opening in the embryo nd All Chordata share four features: – Notochord supports body – Nervous system develops from dorsal nerve cord – Embryos have pharynx with slits – Embryos have tail that extends past anus Tunicates (Urochordates) Tunicates (Urochordates) Larva is free­swimming Adult is sessile and baglike with no coelom Both stages are filter feeders Pharynx serves in both feeding and respiration Lancelets (Cephalochordates) Lancelets (Cephalochordates) Fish­shaped filter feeders Simple brain Segmented muscles Chordate characteristics of adult: – Notochord lies under dorsal nerve cord – Pharynx has gill slits – Tail extends past anus Trends in the Evolution Trends in the Evolution of Vertebrates Shift from notochord to vertebral column Nerve cord expanded into brain Evolution of jaws Paired fins evolved, gave rise to limbs Gills evolved, gave rise to lungs Existing Jawless Fishes­ The Existing Jawless Fishes­ The Lamprey (Agnatha) and Hagfish Cylindrical body No paired fins Cartilaginous skeleton Hagfish tentacles gill slits (twelve pairs) gill openings (seven pairs) mucous glands Lamprey Evolution of Evolution of Jaws First fishes lacked supporting structures Early jawless fish (agnathan) gill slit jaws Jaws are jaw spiracle jaw support Early jawed fish (placoderm) modifications of anterior gill supports Modern jawed fish (shark) jaw Fig. 26-7, p.436 Jawed Fishes Jawed Fishes Most diverse and numerous group of vertebrates Two classes: – Chondrichthyes (cartilaginous fishes) – Osteichthyes (bony fishes) Cartilaginous Fishes: …… The Boney Fish: Cartilaginous Fishes: …… The Boney Fish: Class Chondrichthyes……..Class Ostiechthyes Most are marine predators Cartilaginous skeleton Main groups: – Skates and rays – Sharks – Chimaeras (ratfishes) Includes 96 percent of living fish species Three subclasses: – Ray­finned fishes – Lobe­finned fishes – Lung fishes Early Amphibians: the emergence Early Amphibians: the emergence to land . Fishlike skull and tail Four limbs with Ichthyostega digits Short neck Acanthostega Early tetrapod Fig. 26-10c, p.439 From Fins to Limbs From Fins to Limbs Genetic enhancer controls genes involved in formation of digits on limb bones Change in a single master gene can drastically alter morphology Move in a fish­like manner Modern Amphibians Modern Amphibians Includes:Frogs, Toads,Salamanders,Caecillans All require water at some stage in the life cycle; most lay eggs in water Lungs are less efficient than those of other vertebrates Skin serves as respiratory organ Amphibians on the Decline Amphibians on the Decline Of about 5,500 known species of amphibians, 200 have plummeting populations ­ attributed to habitat deterioration Amphibians are losing standing water pools (where they deposit their eggs) to development and farming Threats to Amphibians: introduction of new species long­term climate changes increases in ultraviolet radiation spread of fungal and parasitic disease chemical contamination of aquatic habitats Rise of Amniotes Rise of Amniotes Arose during Carboniferous Adaptations to life on land – Tough, scaly skin – Internal fertilization – Amniote eggs – Water­conserving kidneys Evolutionary History of Amniotes Evolutionary History of Amniotes snakes lizards stem reptiles ichthyosaurs pterosaurs birds dinosaurs tuataras archosaurs crocodilians plesiosaurs turtles anapsids synapsids Carboniferous Permian Triassic Jurassic therapsids (mammals) Cretaceous Fig. 26-14 p.442 So Long, Dinosaurs So Long, Dinosaurs Mass extinction between the Cretaceous­Tertiary boundary K­T asteroid impact theory Global broiling hypothesis LIVING REPTILES: Crocodilians, LIVING REPTILES: Crocodilians, Turtles,Tuataras,Snakes and lizards SNAKES AND LIZARDS Largest order (95 percent of living reptiles) Most lizards are insectivores with small peglike teeth All snakes are carnivores with highly movable jaws TUATARAS Only two living species Live on islands off coast of New Zealand Look like lizards, but resemble amphibians in some aspects of their brain and in their way of walking Amniote eggs Internal fertilization Scaly skin Kidneys conserve water TURTLES Armorlike shell Horny plates instead of teeth Lay eggs on land Amniote Egg:the end to dependency on Amniote Egg water for the life cycle embryo yolk sac amnion allantois chorion albumin hardened shell Fig. 26-20, p.446 olfactory lobe adaptations to life on land, in addition to the amniote egg!! hindbrain, midbrain, forebrain vertebral column gonad spinal cord kidney Crocodile Body Plan:note all the Crocodile Body Plan snout heart esophagus stomach intestine cloaca liver Fig. 26.16, p. 454 Birds Birds Diverged from small theropod dinosaurs during the Mesozoic Feathers are a unique trait – Derived from reptilian scales – Serve in insulation and flight Adapted for Flight Adapted for Flight Four­chambered heart Highly efficient respiratory system with air spaces Lightweight bones Powerful muscles attach to the keel Fig. 26-22, p.447 Adaptive radiation after the extinction of the dinosaurs Mammals: Phylum Mammalia: Mammals: Phylum Mammalia: Hair Mammary glands Distinctive teeth Highly developed brain Extended care for the young Adaptive radiation after the extinction of the dinosaurs Fig. 26-23, p.448 Three Mammalian Lineages Three Mammalian Lineages Monotremes – Egg­laying mammals Marsupials – Pouched mammals Eutherians – Placental mammals ROLE OF GEOLOGIC CHANGE Placental mammals evolved after what would become Australia had split off No placental mammals in Australia Elsewhere, placental mammals replaced most marsupials Living Monotremes, Marsupials, Living Monotremes, Marsupials, and Placental Mammals (Eutherians) Monotremes: Duck­billed platypus Two kinds of spiny anteater All lay eggs Marsupials: Most of the 260 species are native to Australia and nearby islands Only the opossums are found in North America Young are born in an undeveloped state and complete development in a permanent pouch on mother Placential Mammals The Eutherians: Most diverse mammalian group Placental mammals develop more quickly than marsupials Young develop in mother’s uterus Placenta composed of maternal and fetal tissues; nourishes fetus, delivers oxygen, and removes wastes ...
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This note was uploaded on 12/02/2009 for the course SCI 013 taught by Professor Xxx during the Fall '09 term at Purdue University Calumet.

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