Study traces AIDS virus origin to 100 years ago

1. Study traces AIDS virus origin to 100 years ago “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.”

3. cynodonts

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

5. cynodonts Mammaliamorpha Mammaliaformes

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

7. TraitPelycosaursTherapsidsCynodonts Posture: sprawling intermediate upright Teeth: weakly heterodont increasingly heterodont strongly hetero Palate: no secondary palate partial complete “-apsidy” small temporal fenestra enlarged fenestra vastly expanded Postdentary bones: present, large present, reduced absent greatly reduced

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

9. Mammalia Mammaliaformes Mammaliamorpha

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

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

12. Mammalia Mammaliaformes Mammaliamorpha

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

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

21. Extant mammalian diversity Class MAMMALIA Subclass Prototheria Subclass Theria Infraclass Metatheria 1 Order (Monotremata) 2 Families 3 5 species 7 Orders 19 21 Families 272 331 species xx x xxx Infraclass Eutheria xx 18 21 Orders 114 130 Families 4354 5078 species xxx 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” K/T boundary “Age of Dinosaurs”

24. Tertiary

25. K/T boundary

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

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

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

34. Subclass Prototheria 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).

35. Subclass Prototheria 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.

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

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

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

40. Subclass Prototheria 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)

41. Subclass Prototheria 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)

43. Subclass Prototheria SKELETAL FEATURES:

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

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

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