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Four Key Chordate Characteristics

Four Key Chordate Characteristics. Macroevolution is above the species level. Microevolution is at the species level. Invertebrate Chordates. Cephalochordata - Lancelets/Amphioxus Urochordata Tunicates/Sea Squirts

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Four Key Chordate Characteristics

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  1. Four Key Chordate Characteristics

  2. Macroevolution is above the species level. Microevolution is at the species level.

  3. Invertebrate Chordates • Cephalochordata -Lancelets/Amphioxus • Urochordata • Tunicates/Sea Squirts • Vertebrates may have evolved from a sexually mature larval urochordate • Metamorphosis is eliminated

  4. Subphylum Cephalochordata: the Lancelet Branchiostoma

  5. Lancelet Anatomy

  6. Subphylum Urochordata Tunicate Anatomy

  7. Subphylum: Vertebrata • Cephalization (Craniates are chordates with a head) • Vertebrate skeleton • Brain protected by skull • Closed circulatory system • Gills or lungs • Kidneys for excretion

  8. Fish Fishes • Very successful vertebrates • Fast streamlined body plan • Excellent sensory organs, lateral line system • Highly developed organs for osmoregulation • Complex behavior • 2 chambered heart • Swim bladder

  9. A Sea Lamprey (Class Cephalospidomorphi)

  10. A Hagfish (Class Myxini)

  11. Hypothesis for the evolution of vertebrate jaws from two pairs of skeletal rods

  12. Gnathostomes Are Vertebrates That Have Jaws

  13. Class Chondrichthyes

  14. Ray-finned Fishes; Yellow Perch; Have thin bony spines connected by a layer of skin to form the fins

  15. Ray-finned Fishes (Class Actinopterygii): long-snouted sea horse

  16. A coelocanth (Class Actinistia), a Lobe-finned Fish, has rod-shaped bones and few bones in its fin bases

  17. Coelacanth at the Field Museum - Chicago

  18. Fossilized and modern coelocanths

  19. Problems: No support on land Gills stick together Ammonia no longer a good source of excretory waste Dehydration Sound/light /smell is perceived differently on land Solutions cartilage  bone Lungs Excrete concentrated urea  uric acid Skin and scales Adapt ability to perceive sound, smell and light differently Life on Land

  20. Skeleton of Acanthostega, a Devonian tetrapod fish

  21. Class Amphibia • Shoulder hip and girdles act to strengthen limbs for life on land • Heart with 3 chambers • They are not completely free from water • Reproduction – most oviparous • Dessication (skin must stay wet) • Cloaca – where wastes and eggs leave the body

  22. Amphibian Orders: Newt (left) Order Urodela, frog (right) Order Anura

  23. Frogs

  24. “Dual life” of a frog (Rana temporaria)

  25. Class Reptilia • Completely free from water • Amniotic egg • Scaly skin • 3-4 chambered heart • Uric acid as nitrogenous waste • Ectothermic

  26. Extant Reptiles: Desert tortoise (top left), lizard (top right), king snake (bottom left), alligators (bottom right)

  27. Banded Gecko, Coleonyx varigatus

  28. Emerald Tree Boa

  29. Sea Turtle

  30. Archaeopteryx

  31. Archaeopteryx

  32. Cretaceous theropod dinosaurs with putative feathers from Chinese sediments: Caudipteryx

  33. Class Mammalia • Hair • Mammary glands • Diaphragm for ventilation of lungs • Single jawbone, specialized teeth • large brains • 4 chambered heart • Endothermic

  34. Major Groups of Mammals • Monotremes: • Platypuses, spiny anteater - lay eggs • Mixture of reptilian and mammalian traits • Marsupials • Non-placental – Kangaroo, koala, opossum • Young born early and complete development within pouch • Placental Mammals – bats, dogs, us!

  35. Major Orders of Mammals (Monotremata-Sirenia)

  36. Major Orders of Mammals (Edentata-Primates)

  37. Major Orders of Mammals (Carnivora-Cetaceans)

  38. Major Orders of Mammals (Perissodactyla-Insectivora)

  39. Hypothetical Cladogram of Mammals

  40. Class Aves • Evolved from reptiles • Flying dinosaurs • Bones and feathers are adapted for flight • 4 chambered heart • Endothermic • Efficient 1 way lungs • Excrete uric acid

  41. A small sample of birds: Blue-footed boobies (top left), male peacock (top right), penguins (bottom left), perching bird (bottom right)

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