1. “REPTILIAN” vs MAMMALIAN
DENTITION

2. MOLARS OF MESOZOIC
PROTOTHERIANS

3. MOLARS OF MULTITUBERCULATES
& MONOTREMES
Multituberculata
Ptilodus
Monotremata
Obdurodon Ornithorhynchus

4. EVOLUTION OF THERIAN MOLARS
Tribosphenic

5. THERIAN (TRIBOSPHENIC) MOLARS
(occlusal view)
upper
lower
(lateral view)

6. TRIBOSPHENIC MOLAR OCCLUSION

7. Variations on Tribosphenic molar
ectoloph
Dilambdodont
(insectivore)
Quadrate or Bunodont
(primate)

8. MOLARS – crowns & roots

9. Lophodont molar (murid rodents)

10. Selenodont molar (artiodactyls)

11. Loxodont molar
(elephant)
(capybara)

12. DENTAL FORMULA
Canis lupus
Upper dentition
(one side only)
I C P M
I c p m
Lower dentition
(one side only)
________
(x 2) = 42

13. DENTAL FORMULAS

14. Extreme dentitions Nine-banded armadillo (Dasypus)
simplification and reduction
Common dolphin (Delphinus)
simplification and multiplication

15. EARLY MAMMAL GROUPS

16. ORDER SYMMETRODONTA basal therians
Kuehneotherium
late Triassic – early Jurassic
Europe
Hadrocodium
earlyJurassic, China
Vincelestes
early Cretaceus, Argentina

17. Loss of post-dentary bones in lower jaw
SYMMETRODONTS
Loss of post-dentary bones in lower jaw
Hadrocodon (Docodont, Prototherian)
Hadrocodium (Symmetrodont, basal Therian)

18. SYMMETRODONT
Molar structure

19. Sinodelphys -- early Cretaceous (China)
OLDEST MARSUPIAL?
Sinodelphys -- early Cretaceous (China)
= 50

20. Eomaia -- early Cretaceous (China)
OLDEST EUTHERIAN ?
Eomaia -- early Cretaceous (China)
_______
= 54

21. Ukhaatherium late Cretaceus, Mongolia
EARLY EUTHERIAN
Ukhaatherium late Cretaceus, Mongolia
_________
= 50

22. Skulls of early therians

23. Skulls of early therians

24. ORDER: DIDELPHIMORPHIA Family: Didephildae
EARLY METATHERIAN
ORDER: DIDELPHIMORPHIA
Family: Didephildae
Alphadon (Late Createous, N. America)
= 50

25. early diversification To Antarctica & Australia
MARSUPIAL BIOGEOGRAPHY
Asian origin?
(early Cretaceous)
To N. America
early diversification
(late Cretaceous)
Reinvasion of N. America
(Quaternary)
Extinction on northern continents
(mid Tertiary)
To S. America
(early Cretaceous)
Ameridelphian
diversification
(late Cretaceous)
To Antarctica & Australia
(early Tertiary)
Australodelphian
Isolation and
diversification
(Tertiary)
Isolation of
southern continents
(late Cretaceous)

26. CLADOGRAM OF RECENT MARSUPIALS Ameridelphia Australodelphia
(outgroups)

27. MARSUPIAL CLASSIFICATION

28. Marsupial – Placental differences Cranial & dental morphology
Didelphis Canis

29. ________
__________
= 50
= 44-54