Post on 03-Jan-2016
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“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
cynodonts
Mammaliamorpha
Mammaliaformes
Mammalia: All descendants fromthe MRCA of living mammals.
cynodonts
Mammaliamorpha
Mammaliaformes
cynodonts
Mammaliaformes (formation of dentary-squamosal“single jaw hinge” complete)
cynodonts
Mammaliamorpha (transition todentary-squamosal joint begins)
Trait Pelycosaurs Therapsids CynodontsPosture: sprawling intermediateupright
Teeth: weakly heterodont increasingly heterodontstrongly hetero
Palate: no secondary palate partialcomplete
“-apsidy” small temporal fenestra enlarged fenestravastly expanded
Postdentary bones: present, large present, reducedabsent
greatly reduced
Mammaliaformes (formation of dentary-squamosal“single jaw hinge” complete)
Mammalia: All descendants fromthe MRCA of living mammals.
cynodonts
Mammaliamorpha (transition todentary-squamosal joint begins)
Mammaliamorpha
Mammaliaformes
Mammalia
Morganucodon
•Completion of dentary-squamosal jaw joint•Cheekteeth divided into premolars and molars•Diphyodonty
•BUT TINY! For 170 million years!
Pa
leo
zoic
Me
sozo
icMammalia (and some mammaliaforms)
Mammaliamorpha
Mammaliaformes
Mammalia: All descendants fromthe MRCA of living mammals.
cynodonts
Mammaliamorpha
Mammaliaformes
Mammalia
Multituberculates (extinct prototherians)
Multituberculates (extinct prototherians)
Late Jurassic-Mid. Miocene (ca. 150 m.y.)
Multituberculates (extinct prototherians)
Late Jurassic-Mid. Miocene (ca. 150 m.y.)
Diverse, found on all continents
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
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...)
Mammaliamorpha
Mammaliaformes
Mammalia (CLASS)
Met
ath
eria
Met
ath
eria
Eu
ther
iaE
uth
eria
Theria(SUBCLASS)
ProtoPrototheria (SUBCLASS)theria (SUBCLASS)
(INFRACLASSES)(INFRACLASSES)
Extant mammalian diversity
1 Order (Monotremata)2 Families3 species
Infraclass Metatheria
Infraclass Eutheria
7 Orders19 Families272 species
18 Orders114 Families4354 species
Subclass Prototheria Subclass Theria
Class MAMMALIA
Extant mammalian diversity
1 Order (Monotremata)2 Families3 5 species
Infraclass Metatheria
Infraclass Eutheria
7 Orders19 21 Families272 331 species
18 21 Orders114 130 Families4354 5078 species
Subclass Prototheria Subclass Theria
Class MAMMALIA
xxxxxx
xxxxx
xxxx
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?
“Age of Mammals”
“Age of Dinosaurs”
K/T boundaryK/T boundary
Tert
iary
K/TK/Tboundaryboundary
Most/all eutherian orders originated & diversifyAFTER K/T
(traditionally, fossils supported this)
Most/all eutherian orders originated & diversifyAFTER K/T
(traditionally, fossils supported this)
Orders originate BEFORE K/T but don’t diversify untilAFTER K/T
(more recently discovered fossils support)
Most/all eutherian orders originated & diversifyAFTER K/T
(traditionally, fossils supported this)
Orders originate BEFORE K/T but don’t diversify untilAFTER K/T
(more recently discovered fossils support)
Most orders originate & diversify BEFORE K/T(older molecular studies support)
1 Order (Monotremata) 2 Families
Tachyglossidae (echidnas or “spiny anteaters”)4 species.
Ornithorhynchidae (platypus)1 species
Subclass Prototheria
Few fossils, never very diverse. BUT PERSISTED.
Subclass Prototheria
Few fossils, never very diverse. BUT PERSISTED.
Echidnas: fossils from 55-60 Mya, oldest in S. AMERICA
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).
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.
Subclass Prototheria
SKULL FEATURES:
•No teeth in living adults BUT fossil platys & living neonates have, then lose. LOSS=apomorphy
Subclass Prototheria
SKULL FEATURES:
•No teeth in living adults BUT fossil platys & living neonates have, then lose. LOSS=apomorphy•No lacrimals (APOMORPHY)
Subclass Prototheria
SKULL FEATURES:
•No teeth in living adults BUT fossil platys & living neonates have, then lose. LOSS=apomorphy•No lacrimals (APOMORPHY)
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)
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)
Subclass Prototheria
SKELETAL FEATURES:
Subclass Prototheria
SKELETAL FEATURES:•Epipubic bones present, large (PLESIOMORPHY)
Subclass Prototheria
SKELETAL FEATURES:•Epipubic bones present, large (PLESIOMORPHY)•Cervical ribs (PLESIOMORPHY)
Subclass Prototheria
SKELETAL FEATURES:•Epipubic bones present, large (PLESIOMORPHY)•Cervical ribs (PLESIOMORPHY)•Horny, hollow spur on inside of ankle (APOMORPHY)
Subclass Prototheria
Warren et al. (2008). Nature 453, 175-183.
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
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
OTHER FEATURES:•Pouch (echidnas only)
Subclass Prototheria
OTHER FEATURES:•Pouch (echidnas only)•Testes permanently abdominal (no scrotum)
Subclass Prototheria
OTHER FEATURES:•Pouch (echidnas only)•Testes permanently abdominal (no scrotum)•Uteri fused
Subclass Prototheria
OTHER FEATURES:•Pouch (echidnas only)•Testes permanently abdominal (no scrotum)•Uteri fused•Leathery egg with nutrient-rich yolk
Subclass Prototheria
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
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 Tb and metabolic rates
Subclass Prototheria
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 Tb and metabolic rates•Electroreception (snout), including echidnas
Subclass Prototheria