1. “Researchers took advantage of the fact that HIV mutates rapidly. So two strains from a common ancestor quickly become less and less alike in their genetic material over time. That allows scientists to "run the clock backward" by calculating how long it would take for various strains to become as different as they are observed to be. That would indicate when they both sprang from their most recent common ancestor. The new work used genetic data from the two old HIV samples plus more than 100 modern samples to create a family tree going back to these samples' last common ancestor. Researchers got various answers under various approaches for when that ancestor virus appeared, but the 1884-to-1924 bracket is probably the most reliable, Worobey said.” Study traces AIDS virus origin to 100 years ago

3. cynodonts

4. Mammaliamorpha Mammaliaformes Mammalia: All descendants from the MRCA of living mammals. cynodonts

5. Mammaliamorpha Mammaliaformes cynodonts

6. Mammaliaformes (formation of dentary-squamosal “single jaw hinge” complete) cynodonts Mammaliamorpha (transition to dentary-squamosal joint begins)

7. TraitPelycosaursTherapsidsCynodonts Posture:sprawlingintermediateupright Teeth:weakly heterodontincreasingly heterodontstrongly hetero Palate:no secondary palatepartialcomplete “-apsidy”small temporal fenestraenlarged fenestravastly expanded Postdentary bones:present, largepresent, reducedabsent greatly reduced

8. Mammaliaformes (formation of dentary-squamosal “single jaw hinge” complete) Mammalia: All descendants from the MRCA of living mammals. cynodonts Mammaliamorpha (transition to dentary-squamosal joint begins)

9. Mammaliamorpha Mammaliaformes Mammalia

10. Morganucodon Completion of dentary-squamosal jaw joint Cheekteeth divided into premolars and molars Diphyodonty BUT TINY! For 170 million years! Paleozoic Mesozoic Mammalia (and some mammaliaforms)

11. Mammaliamorpha Mammaliaformes Mammalia: All descendants from the MRCA of living mammals. cynodonts

12. Mammaliamorpha Mammaliaformes Mammalia

13. Multituberculates (extinct prototherians)

14. Multituberculates (extinct prototherians) Late Jurassic-Mid. Miocene (ca. 150 m.y.)

15. Multituberculates (extinct prototherians) Late Jurassic-Mid. Miocene (ca. 150 m.y.) Diverse, found on all continents

16. Multituberculates (extinct prototherians) Late Jurassic-Mid. Miocene (ca. 150 m.y.) Diverse, found on all continents Ever-growing lower incisors, plagialacoid (blade-like) molariform teeth

17. Multituberculates (extinct prototherians) Late Jurassic-Mid. Miocene (ca. 150 m.y.) Diverse, found on all continents Ever-growing lower incisors, plagialacoid (blade-like) molariform teeth Outcompeted to extinction? (rodents, early primates...)

18. Mammaliamorpha Mammaliaformes Mammalia (CLASS) Metatheria Eutheria Theria (SUBCLASS) Prototheria (SUBCLASS) (INFRACLASSES)

20. Extant mammalian diversity 1 Order (Monotremata) 2 Families 3 species Infraclass Metatheria Infraclass Eutheria 7 Orders 19 Families 272 species 18 Orders 114 Families 4354 species Subclass PrototheriaSubclass Theria Class MAMMALIA

21. Extant mammalian diversity 1 Order (Monotremata) 2 Families 3 5 species Infraclass Metatheria Infraclass Eutheria 7 Orders 19 21 Families 272 331 species 18 21 Orders 114 130 Families 4354 5078 species Subclass PrototheriaSubclass Theria Class MAMMALIA x xx xxx xx xxxx

22. The radiation of placental mammals Since end of Mesozoic, placental (eutherian) mammals dominant terrestrial vertebrates on all continents except Australia and Antarctica. When and why did this diversification occur?

23. “Age of Mammals” “Age of Dinosaurs” K/T boundary

24. Tertiary

25. K/Tboundary

26. Most/all eutherian orders originated & diversify AFTER K/T (traditionally, fossils supported this)

27. Most/all eutherian orders originated & diversify AFTER K/T (traditionally, fossils supported this) Orders originate BEFORE K/T but don’t diversify until AFTER K/T (more recently discovered fossils support)

28. Most/all eutherian orders originated & diversify AFTER K/T (traditionally, fossils supported this) Orders originate BEFORE K/T but don’t diversify until AFTER K/T (more recently discovered fossils support) Most orders originate & diversify BEFORE K/T (older molecular studies support)

31. 1 Order (Monotremata) 2 Families Tachyglossidae (echidnas or “spiny anteaters”) 4 species. Ornithorhynchidae (platypus) 1 species Subclass Prototheria

32. Few fossils, never very diverse. BUT PERSISTED. Subclass Prototheria

33. Few fossils, never very diverse. BUT PERSISTED. Echidnas: fossils from 55-60 Mya, oldest in S. AMERICA Subclass Prototheria

34. Few fossils, never very diverse. BUT PERSISTED. Echidnas: fossils from 55-60 Mya, oldest in S. AMERICA Platypus: fossils from 120 Mya, oldest in AUSTRALIA (Paleocene fossils in S. AMERICA). Subclass Prototheria

35. Few fossils, never very diverse. BUT PERSISTED. Echidnas: fossils from 55-60 Mya, oldest in S. AMERICA Platypus: fossils from 120 Mya, oldest in AUSTRALIA (Paleocene fossils in S. AMERICA). Many plesiomorphic features, but some apomorphies. Subclass Prototheria

36. SKULL FEATURES: No teeth in living adults BUT fossil platys & living neonates have, then lose. LOSS=apomorphy Subclass Prototheria

38. SKULL FEATURES: No teeth in living adults BUT fossil platys & living neonates have, then lose. LOSS=apomorphy No lacrimals (APOMORPHY) Subclass Prototheria

39. SKULL FEATURES: No teeth in living adults BUT fossil platys & living neonates have, then lose. LOSS=apomorphy No lacrimals (APOMORPHY) Subclass Prototheria

40. SKULL FEATURES: No teeth in living adults BUT fossil platys & living neonates have, then lose. LOSS=apomorphy No lacrimals (APOMORPHY) Cranial sutures fused, indistinct (APOMORPHY) Subclass Prototheria

41. SKULL FEATURES: No teeth in living adults BUT fossil platys & living neonates have, then lose. LOSS=apomorphy No lacrimals (APOMORPHY) Cranial sutures fused, indistinct (APOMORPHY) Jugal reduced or absent (APOMORPHY) Subclass Prototheria

43. SKELETAL FEATURES: Subclass Prototheria

44. SKELETAL FEATURES: Epipubic bones present, large (PLESIOMORPHY) Subclass Prototheria

47. SKELETAL FEATURES: Epipubic bones present, large (PLESIOMORPHY) Cervical ribs (PLESIOMORPHY) Subclass Prototheria

48. SKELETAL FEATURES: Epipubic bones present, large (PLESIOMORPHY) Cervical ribs (PLESIOMORPHY) Horny, hollow spur on inside of ankle (APOMORPHY) Subclass Prototheria

51. Warren et al. (2008). Nature 453, 175-183.

52. SKELETAL FEATURES: Epipubic bones present, large (PLESIOMORPHY) Cervical ribs (PLESIOMORPHY) Horny, hollow spur on inside of ankle (APOMORPHY) Pectoral girdle with large precoracoids, coracoids, interclavicle (PLESIOMORPHY) Subclass Prototheria

54. SKELETAL FEATURES: Epipubic bones present, large (PLESIOMORPHY) Cervical ribs (PLESIOMORPHY) Horny, hollow spur on inside of ankle (APOMORPHY) Pectoral girdle with large precoracoids, coracoids, interclavicle (PLESIOMORPHY) Skeleton sprawling, “reptilian” (PLESIOMORPHY) BUT, good for swimming, digging. Subclass Prototheria

56. OTHER FEATURES: Pouch (echidnas only) Subclass Prototheria

57. OTHER FEATURES: Pouch (echidnas only) Testes permanently abdominal (no scrotum) Subclass Prototheria

58. OTHER FEATURES: Pouch (echidnas only) Testes permanently abdominal (no scrotum) Uteri fused Subclass Prototheria

59. OTHER FEATURES: Pouch (echidnas only) Testes permanently abdominal (no scrotum) Uteri fused Leathery egg with nutrient-rich yolk Subclass Prototheria

60. OTHER FEATURES: Pouch (echidnas only) Testes permanently abdominal (no scrotum) Uteri fused Leathery egg with nutrient-rich yolk Rostrum lacks vibrissae, elongate cloaca (but....) Subclass Prototheria

63. OTHER FEATURES: Pouch (echidnas only) Testes permanently abdominal (no scrotum) Uteri fused Leathery egg with nutrient-rich yolk Rostrum lacks vibrissae, elongate cloaca (but...) Endothermic, but low T b and metabolic rates Subclass Prototheria

64. OTHER FEATURES: Pouch (echidnas only) Testes permanently abdominal (no scrotum) Uteri fused Leathery egg with nutrient-rich yolk Rostrum lacks vibrissae, elongate cloaca (but...) Endothermic, but low T b and metabolic rates Electroreception (snout), including echidnas Subclass Prototheria