Phylum Chordata

1. Phylum Chordata • Subphylum Urochordata – • Subphylum Cephalochordata – • Subphylum Vertebrata – • 48,000 species • Range in size from tiny fish to huge whales • Occupy all of Earth’s biomes

2. Craniates • 2 defining characteristics compared to nonvertebrate chordates • _____________- embryonic cells that will disperse throughout the embryo contributing to the development of the skeleton, nerves, jaws, and teeth • Also, at least 2 Hox clusters

3. ___________, finless, marine fish that lack vertebrae Essentially blind with a keen sense of ____ Copious amounts of ________ Class ___________

4. Vertebrates • All chordate and craniate characteristics plus • _____________- notochord is replaced by a bony or cartilaginous column of interlocking vertebrae • ______________ of cartilage or bone – most also have two pairs of appendages • Internal organs - liver, kidneys, endocrine glands, and a heart with at least two chambers • Heart, kidneys, and endocrine system are more complex than analogous structures in other taxa

5. The fish • Key innovation in vertebrate evolution is _____________________ • Developed first in ______ • Agnathans – • Gnathostomes – ________ with 2 additional Hox clusters

6. Class ____________________ • ____________________and true appendages • Do possess a ____________ and rudimentary _______________________ • One of the most primitive groups of vertebrates • Found in marine and freshwater • Marine lampreys ___________ as adults

8. Hinged jaws developed from the pharnygeal arches • Descent with modification

9. Class ____________________ • Sharks, skates, rays • Skelton composed of _______________ • Derived not ancestral character • Sharks among earliest fish to develop teeth

10. Denser than water – • 2 chambered heart – single circulation • Powerful sense of _______ • Lateral line – • Internal fertilization • ___________ – lay eggs • ___________ – egg retained in female, no placenta • ___________ – eggs develop in uterus, placenta nourishes young

12. Bony fish • 3 living classes • ______________ – ray-finned fish • ______________ – coelacanths • ______________ – lungfish • 3 features different from Chondricthyes

14. Actinopterygii – ray-finned fish • Includes all bony fish but __________ and __________ • Fins supported by thin…

15. _______________ – coelacanths • Believed extinct until ________ • Special joint in skull gives powerful bite • Instead of vertebral column has hollow notochord filled with oil-like fluid

16. ___________ – lungfish • 3 genera with 6 species • Live in… • Both … • Will drown if unable to breathe air

17. Tetrapods • Transition to land meant adaptations to prevent desiccation and locomotion and reproduction on land possible • Vertebral column strengthened, _______ ________ bones braced against backbone • Relatively simple changes in gene expression, especially …

19. Transitional taxa ____________ – retained adaptations for aquatic life – stem species Species increasingly fed on land but tied to water for reproduction Vertebral column and hip and shoulder bones grew even sturdier Evolution of rib cage

20. Davis, Capecchi, and Colleagues Showed a Genetic-Developmental Explanation for Limb Length in Tetrapods • Specific Hox genes are responsible for determining limb formation in mice • Mutations in the genes HoxA-11 and HoxD-11 resulted in the loss of the radius, ulna, and some of the carpals • Relatively simple mutations can control relatively large changes in limb development

22. Amphibians • Successfully invaded land but must return • Buccal pumping to force air into lungs • 3 chambered heart • Fertilization external • Metamorphosis regulated by thyroid hormones

23. Order __________ – frog and toads • Nearly ______ of amphibians • Order __________ – salamanders • Paedomorphosis – adult has larval characteristics • Order _____________ – caecilians • Legless, nearly blind tropical • Secondarily legless • Uterine milk nourishes young inside mother’s body

25. _______________ • Critical innovation was the development of a … • Amniotic egg broke tie to water

26. 4 extraembryonic membranes ___________ – protects embryo in amniotic cavity _________ – yolk _________ – disposal of wastes _________ – with allantois for gas exchange

27. Other key innovations • ________________ resistant skin • ________________ – negative pressure sucks air in • _______________________________ – concentrate waste prior to elimination

28. _______________________ • Classification under revision • One class or four? • Class • Class • Class • Class

29. Virtually unchanged for 200 million years Hard protective shell In most… Lack _________ but have sharp beak Class _____________

30. ____________ with extremely mobile joints Lizards have … Class ___________________

31. Crocodiles and alligators Essentially unchanged for 200 million years 4 chambered heart Teeth in sockets Care for young Class _________________

32. Dinosaurs • Class ___________ – bird-hipped dinosaurs • Class ___________ – lizard-hipped dinosaurs • Legs of dinosaurs were positioned directly under the body

33. The Differentiation of Scales, Feathers, and Fur May Be Caused by Simple Changes in Developmental Pathways • Epithelial appendages (scales, feathers, hair, fur) look different but share similarities in initial development • All originate as epithelial placodes • Timing and expression of regulatory molecules determines the appendage that develops in the dermal layer

35. ______________ lithographica • Except for feathers very similar to dinosaurs • ______________ zoui • ______________ sanctus • Completely feathered, lacking bony tail and toothed jaw

36. Class _____________ • 4 features unique to birds (for flight) • _____________________ – thin, hollow, honeycombed • _________ to anchor flight muscles, no teeth • _______________ – very efficient breathing • ___________________ – single ovary, no urinary bladder

38. Double circulation with 4 chambered heart • Acute vision • Eggs brooded • 28 orders, 9600 species

39. ________________ • Evolved from amniote ancestors earlier than birds • Appeared about 220 mya • _________________________ mammals flourished • Range of…

40. Distinguishing characters • Only vertebrates with … • Skull • Pinnae, external ears • Brain enlarged in large skull

42. Some but not all mammals • Digest plants using … • Horns and antlers • Horns – • Antlers –

43. Subclass __________ – Order ______________ • __________________lay eggs, lack placenta, poorly developed nipples • Subclass __________ – ______________ • 7 orders • Once widespread, now confined mostly to ____________ • ____________ found in North America • Very undeveloped young must make it to ____________ to finish development

44. Subclass _________ • Placenta provides _____________ • 18 orders

45. Primates • Primarily tree-dwelling species • Evolved about 85 mya • Defining characteristics • Some digits have… • Binocular vision

46. ______________ • Bush babies, lemurs, pottos, tarsiers • Generally nocturnal and smaller-brained • ______________ • Monkeys • Tails, monkeys cannot swing from branch to branch • ______________ – gibbons, gorillas, orangutans, chimpanzees and humans • Family Hylobatidae – lesser apes or gibbons • Family Hominidae – greater apes

47. Humans • Related to chimpanzees and apes but not… • All hominoids shared a common ancestor • _________ lineage leading to humans separated from other primates • 1 or 2 hominid species coexisting at one time

48. ________ resulted in many changes – spine sits underneath skull, broader pelvis, lower limbs larger • ___________________ – widespread, at least 6 species, relatively small, facial structure and brain size similar to chimp • ______ – increased brain size, stone tools • Homo sapiens 3,000 years ago • Taller, lighter-weight, slightly smaller brain capacity than H. neanderthalensis • ____________hypothesis supported over multiregional hypothesis