1. Animal Evolution – The Chordates Chapter 26 Part 1

2. Impacts, Issues Transitions Written in Stone  Fossils such as Archaeopteryx, an ancient winged dinosaur with feathers, are evolutionary evidence of transitions between species

3. 26.1 The Chordate Heritage  Chordates Most diverse lineage of deuterostomes Some are invertebrates; most are vertebrates Bilateral and coelomate Cephalized and segmented Complete digestive system Closed circulatory system Classified by embryonic characteristics

4. Modern Chordate Groups

5. Embryonic Chordate Characteristics  Four characteristics of chordate embryos may not persist in adults Notochord of stiff connective tissue that extends the length of the body and supports it Dorsal, hollow nerve cord parallels the notochord Gill slits across the wall of the pharynx Tail that extends beyond the anus

6. Invertebrate Chordates  Lancelets are the only group of chordates that retains all chordate characteristics as adults

7. Fig. 26-2b, p. 434

8. a Dorsal, hollow nerve cord bNotochordc Pharynx with gill slits d Tail extends beyond anus eyespot tentacle-like structures around mouth segmented muscles (myomeres) midguthindgut aortagonadpore of atrial cavity anusepidermis

9. Animation: Lancelet body plan

10. Invertebrate Chordates  Tunicates have typical chordate larvae, but adults retain only the pharynx with gill slits

11. Fig. 26-3a, p. 435

12. nerve cord notochord gut pharynx with gill slits

13. Fig. 26-3b, p. 435

14. Fig. 26-3c, p. 435

15. pharynx with gill slits

16. Fig. 26-3d, p. 435 1 cm

17. Craniates  Craniates have a braincase of cartilage or bone (cranium) that encases the brain, paired eyes, and other sensory structures on the head  Craniates includes fishes, amphibians, reptiles, birds, and mammals  Hagfishes are the only modern craniates that are not vertebrates

18. Hagfishes  Soft bodied, boneless fishes

19. Fig. 26-4a, p. 435

20. tentaclesgill slits (twelve pairs)mucous glands

21. Fig. 26-4b, p. 435

22. Fig. 26-4c, p. 435

23. 26.1 Key Concepts Characteristics of Chordates  Four traits characterizes the chordates: A supporting rod (notochord) A hollow, dorsal nerve cord A pharynx with gill slits in the wall A tail extending past an anus  Certain invertebrates and all vertebrates belong to this group

24. 26.2 Vertebrate Traits and Trends  Vertebrates are chordates with an internal skeleton (endoskeleton) of cartilage or bone with a supportive backbone (vertebral column) made up of individual vertebrae  Modern vertebrates (except lampreys) have jaws derived from gill-supporting structures

25. Gill-Supporting Structures

26. Fig. 26-6a, p. 437 supporting structure for gill slits gill slits A In early jawless fishes, supporting elements reinforced a series of gill slits on both sides of the body.

27. Fig. 26-6b, p. 437 jaw, derived from support structure B In early jawed fishes (e.g., placoderms), the first elements were modified and served as jaws. Cartilage reinforced the mouth’s rim.

28. Fig. 26-6c, p. 437 location of spiracle (modified gill slit) jaw support jaw C Sharks and other modern jawed fishes have strong jaw supports.

29. Animation: Evolution of jaws

30. Evolution of Internal Skeleton  Fishes evolved appendages (fins) for swimming  Pelvic and pectoral fins gave rise to paired limbs in amphibians, which began the move to land

31. Evolution of Other Systems  Living in water (fish) Blood moves in a single circuit from heart to gills (respiratory organs that function in water)  Moving to land Modification of the respiratory system (lungs) and circulatory system (two circuits) Efficient kidneys to conserve water, and a system of internal fertilization

32. Chordate Family Tree

33. Fig. 26-5, p. 436 lancelets tunicates hagfishes lampreys cartilaginous fishes ray-finned fishes lobe-finned fishes lungfishes amphibians “reptiles” birds mammals amniotes tetrapods swim bladder or lungs jawed vertebrates vertebrates craniates ancestral chordates Origin of the first jawless fishes. Jawed fishes, including the placo- derms and sharks, evolve. Adaptive radiation of fishes, and the first amphibians move onto land. Diversification of fishes and amphibians. Armored fishes go extinct. Reptiles arise and start to diversify. Early amphibians in decline. Dinosaurs and marine reptiles evolve. Birds, mammals, and modern amphibians arise. Dinosaurs dominate. Dinosaur diversity peaks, then extinction by period’s end. Adaptive radiation of mammals. OrdovicianCarboniferousJurassicTertiary 488 443 416 359 299 251 200 146 66 SilurianDevonianPermianTriassicCretaceous

34. Animation: Vertebrate evolution

35. 26.2 Key Concepts Trends Among Vertebrates  In vertebrate lineages, a backbone replaced the notochord  Jaws and fins evolved in water  Fleshy fins with skeletal supports evolved into limbs that allowed vertebrates to walk onto land  On land, lungs replaced gills and circulation changed in concert

36. 26.3 The Jawless Lampreys  Lampreys have no jaws or paired fins; they undergo metamorphosis, and many are parasites of other fishes

37. 26.4 The Jawed Fishes  Jawed fishes typically have paired fins and a body covered with scales  Cartilaginous fishes (Chondrichthyes) have a cartilage skeleton, gill slits, and teeth that shed Sharks and rays  Bony fishes (Osteichthyes) have a bony skeleton, gill covers, and a swim bladder Ray-finned fishes, lungfishes, coelacanth

38. Ray-Finned Bony Fishes

39. Fig. 26-9a, p. 439

40. swim bladderkidney ovarynerve cord brain cloacaintestinestomachliverheart gills

41. Fig. 26-9b, p. 439

42. Fig. 26-9c, p. 439

43. Fig. 26-9d, p. 439

44. Lungfish  Lungfishes have gills and lunglike sacs for breathing air

45. Coelacanth  The only modern lobe-finned fish; closely related to amphibians

46. 26.5 Amphibians— First Tetrapods on Land  Tetrapods (four-legged walkers) Branched from lobe-finned fishes in Devonian  Amphibians Land-dwelling vertebrates that return to water to breed, undergo metamorphosis, and have a three-chambered heart

47. Adapting to Life on Land

48. Fig. 26-12a, p. 440

49. Fig. 26-12b, p. 440

50. Fig. 26-12c, p. 440

51. Fig. 26-12d, p. 440

52. Modern Amphibians  Salamanders and newts Body form most like early tetrapods, side-to-side walking motion  Caecilians Includes many limbless, blind burrowers  Frogs and toads Tailless adults with long, muscular hind legs

53. Salamander and Caecilian

54. Frog

55. 26.6 Vanishing Acts  Amphibians depend on standing water to breed and have a thin skin unprotected by scales  These features make them vulnerable to habitat loss, disease, and pollution – causing deformities and threatening species

56. Frog Deformity

57. 26.3-26.6 Key Concepts Transition from Water to Land  Vertebrates evolved in the seas, where cartilaginous and bony fishes still live  Of all vertebrates, modern bony fishes are most diverse  One group gave rise to aquatic tetrapods (four- legged walkers), the descendants of which moved onto dry land

58. 26.7 The Rise of Amniotes  Amniotes are animals with embryos that develop inside a waterproof egg; their waterproof skin and highly efficient kidneys make them well adapted to dry habitats

59. Amniotes  Four branches of amniotes lead to synapsids (mammals), anapsids (turtles), lizards and snakes, and crocodiles and birds  Reptiles are an artificial group referring to amniotes other than bird or mammals  Dinosaurs are extinct amniotes; birds are their descendents

60. The Ruling Reptiles  For 125 million years, dinosaurs dominated the land and sea (Example: Ichthyosaurs)

61. Amniote Phylogeny

62. Fig. 26-16c, p. 442 snakes lizards “stem” reptiles tuataras ichthyosaurs plesiosaurs birds therapod dinosaurs other dinosaurs pterosaurs archosaurs crocodilians turtles therapsids anapsids synapsids mammals PALEOZOIC ERAMESOZOIC ERA TERTIARY TO PRESENT CARBONIFEROUSPERMIANTRIASSICJURASSICCRETACEOUS

63. 26.8 So Long, Dinosaurs  K-T asteroid impact hypothesis Asteroid impacts changed life on Earth, defining the Cretaceous-Tertiary (K-T) boundary Most dinosaurs became extinct

64. 26.9 Diversity of Modern Reptiles  Reptile characteristics Scale-covered body Cloaca for waste disposal Four approximately equal limbs (except snakes) Internal fertilization Body temperature determined by surroundings (ectotherms)

65. Crocodile Body Plan

66. Fig. 26-18, p. 444 kidney (control of water, solute levels in internal environment) olfactory lobe (sense of smell) hindbrain, midbrain, forebrain spinal cord vertebral column gonad snout unmatched rows of teeth on upper and lower jaws esophagus lung heart liver stomach intestinecloaca

67. Animation: Crocodile body plan

68. Turtles and Tortoises  Turtles and tortoises have a bony, scale- covered shell attached to the backbone

69. Fig. 26-19b, p. 445 hard shellvertebral column

70. Lizards  Lizards, the most diverse reptiles, have many interesting defenses

71. Tuataras  The two remaining species of tuataras have a third eye under the skin of the forehead

72. Snakes  Snakes are legless, but some have bony remnants of hindlimbs

73. Fig. 26-19f (1), p. 445 venom gland hollow fang

74. Crocodilians  Crocodilians, close relatives of birds, are the only reptiles with a four-chambered heart

75. Animation: Bony fish body plan

76. Animation: Cartilaginous fishes

77. Animation: Evolution of limb bones

78. Animation: Jawless fishes

79. Animation: Salamander locomotion

80. Animation: Tortoise shell and skeleton

81. Animation: Tunicate body plan