1. The Chordata
Chapter 34

2. Chordate characteristics

4. Figure 34.1 Clades of extant chordates

5. Subphylum Cephalochordata: the lancelet Branchiostoma

6. Subphylum Cephalochordata: lancelet anatomy

7. Pikaia, the Burgess-shale chordate, with evident somites
Pikaia gracilens, a little worm-like beast that crawled in the mud of a long gone seafloor of the Cambrian era, 530 million years ago. While not particularly impressive in the tooth and claw department, Pikaia is believed to be the founder of the phylum Chordata, whose subsequent evolution had consequences still very much felt today by the rest of the ecosystem. Image digitized from the excellent book The Rise of Fishes, by John A. Long (1995, The Johns Hopkins University Press).
The earliest representative of Phylum Chordata. See the notochord near the dorsal surface. It was a swimmer, but it is not a vertebrate. The rib-like features are muscles.

8. Primitive chordates suggest first steps in their evolution ---

9. Figure 34.1 Clades of extant chordates

10. tunicates

11. The hagfish: a skull of cartilage and primitive eyes, but no jaw, no vertebrae

12. Figure 34.1 Clades of extant chordates

13. Figure A sea lamprey

14. Origin of the jaw: transformation of skeletal rods accompanying gills

15. Figure Cartilaginous fishes (class Chondrichthyes): Great white shark (top left), silky shark (top right), southern stingray (bottom left), blue spotted stingray (bottom right)

16. Figure 34.12a Ray-finned fishes (class Actinopterygii): yellow perch

17. Figure 34.12b Ray-finned fishes (class Actinopterygii): long-snouted sea horse

18. Figure 34.13 Anatomy of a trout, a representative ray-finned fish
lateral-line neuromast from

19. Figure 34.1 Clades of extant chordates

20. Figure 34.7 Phylogeny of the major groups of extant vertebrates

21. Figure 34.18 A coelocanth (Latimeria), the only extant lobe-finned genus

22. Figure 34.15 The origin of tetrapods

23. Figure 34.16 Skeleton of Acanthostega, a Devonian tetrapod fish
Transitional tetrapods -- feet in place but gills and tail with fin

24. Figure 34.17 Amphibian orders: Newt (left), frog (right)

25. Figure 34.18 “Dual life” of a frog (Rana temporaria)

26. Figure 34.22 A hatching reptile

27. Amnion: cushioning chamber for embryo
Figure Amniotic egg
Amnion: cushioning chamber for embryo
Chorion: gas exchange to exterior
Allantois: disposal sac

28. A phylogeny of amniotes

29. Figure Extant reptiles: Desert tortoise (top left), lizard (top right), king snake (bottom left), alligators (bottom right)

30. Figure 25.16 Building a phylogenetic tree of dinosaurs

32. Figure 34.23 A phylogeny of amniotes

33. Figure 34.27x Archaeopteryx
Unlike all living birds, Archaeopteryx had a full set of teeth, a rather flat sternum ("breastbone"), a long, bony tail, gastralia ("belly ribs"), and three claws on the wing which could have still been used to grasp prey (or maybe trees). However, its feathers, wings, furcula ("wishbone") and reduced fingers are all characteristics of modern birds.
Pelvis diagram and extensive discussion, see
Pelvises:
Left, a saurischian carnivore
Center, an ornithischian herbivore
Right, Archaeopteryx

34. Figure 34.27 Archaeopteryx, a Jurassic bird-reptile

35. Figure 34.28b Cretaceous theropod dinosaurs with putative feathers from Chinese sediments: Caudipteryx

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

37. Figure 34.23 A hypothetical phylogeny of amniotes

38. Figure 34.32 Evolution of the mammalian jaw and ear bones

40. Figure 34.36 Hypothetical cladogram of mammals

41. Figure 34.32 Evolutionary convergence of marsupial and eutherian (placental) mammals

42. Figure 34.34 Prosimians:Lemurs

43. A phylogenetic tree of primates

44. The Cenozoic

45. Fig. 24.40: A timeline for some selected hominin species:

46. Australopithecus afarensis and the Laetoli footprints
3.5 mya
3.24 mya

47. The Cenozoic

48. Closeup --- Late Cenozoic

49. Fig. 24.40: A timeline for some selected hominin species:

50. Neanderthal and human

51. Mitochondrial DNA phylogeny for Homo sapiens and H. neanderthalis

52. HUMAN MIGRATIONS

53. Secondary contact between the last Neanderthals and humans