EARLY MAMMALS

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EARLY MAMMALS PROTOTHERIANS TOOTH EVOLUTION
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Class Mammalia Subclass Prototheria
Order Triconodonta Morganucodontidae Amphile
stidae Triconodontidae Order Docodonta
Order Monotremata Subclass
Allotheria Order
Haramiyoidea Order Multituberculata
Subclass Theria Infraclass
Trituberculata Order
Symmetrodonta Kuehnoetheriidae Order
Eupantotheria Dryolestidae Infraclass
Metatheria Infraclass Eutheria
(After Carroll 1988)
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Class Mammaliformes Order
Morganucodontia Morganucodontidae Order
Docodonta Order Haramiyoidea Class
Mammalia Subclass Prototheria Order
Platypoda Order Tachyglossa Subclass
Theriiformes Infraclass Allotheria
Order Multituberculata Infraclass
Triconodontia Infraclass Holotheria
Order Symmetrodontia Order
Eupantotheria Order Metatheria Order
Eutheria (After McKenna Bell 1997)
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MAMMALIAFORMES Morganucodon (late Triassic)
Europe/Asia
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MAMMALIAFORMES Morganucodon
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MAMMALIAFORMES Morganucodon
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MAMMALIAFORMES Morganucodon
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PROTOTHERIA Order Triconodonta Triconodon Juras
sic - Cretaceous
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PROTOTHERIA Order Docodontia Haldanodon
(mid-late Jurassic)
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ALLOTHERIA Order Multituberculata Late
Triassic-Oligocene -- 160 million yrs!
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ALLOTHERIA Order Haramiyoidea Late Triassic
Jurassic, Europe, Greenland Africa
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ALLOTHERIA Order Multituberculata Family
Eucosmodontidae Kryptobaatar late Cretaceous,
Mongolia
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ALLOTHERIA Order Multituberculata Ptilodus
Paleocene N. America
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PROTOTHERIA -- Order Monotremata Family
Ornithorhynchidae
Ornithorhynchus anatinus Pleistocene Recent

Australia
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PROTOTHERIA -- Order Monotremata Family
Ornithorhynchidae (fossil history)
Ornithorhynchus Recent
Obdurodon Miocene, Australia
Permanent tooth
Deciduous teeth
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PROTOTHERIA -- Order Monotremata Family
Ornithorhynchidae (fossil history)
Steropodon Cretaceous, Australia
Kollikodon Cretaceous, Australia
Monotrematum Paleocene, South America
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PROTOTHERIA -- Order Monotremata Family
Tachyglossidae (echidnas)
Tachyglossus Short-beaked echidna -- Recent
(Australia, Tasmania, New Guinea)
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PROTOTHERIA -- Order Monotremata Family
Tachyglossidae (echidnas)
Megalibgwilia -- Pleistocene (Australia)
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PROTOTHERIA -- Order Monotremata Family
Tachyglossidae (echidnas)
Zaglossus Long-beaked echidna
Recent (New Guinea)
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PROTOTHERIA -- Order Monotremata Family
Tachyglossidae (echidnas)
Zaglossus Long-beaked echidna
http//www.arkive.org/species/GES/mammals/Zaglossu
s_spp/Zaglossus_bruijni_08.html?movietypewmMed
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ORDER SYMMETRODOTA earliest therians
Vincelestes early Cretaceus, Argentina
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PROTOTHERIAN - THERIAN CONTRASTS RECENT

RECENT PROTOTHERIANS
THERIANS (monotremes)
(marsupials placentals) Teeth Deciduous
teeth only Permanent
dentition multi-cusped molars
tribosphenic molars Skeleton
(Therapsid features) skull with extra
bones fusion of skull bones
cervical ribs
cervical ribs lost
reptilian shoulder girdle
mammalian shoulder sprawling limb
posture upright limb posture
Reproduction reptilian cloacal opening
separate urogenital

anal openings oviparous
viviparous
mammary glands not
well-developed teats forming teats
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POSSIBLE SUB-ORDER RELATIONSHIPS
MAMMAL POLYPHYLY MONOTREMES
PLUS MULTITUBERCULATES MONOTREMES
PLUS MARSUPIALS PROTOTHERIA
PLUS THERIA (prevailing view)
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TEETH
REPTILIAN vs MAMMALIAN
DENTITION
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MOLARS OF MESOZOIC PROTOTHERIANS
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MOLARS OF MULTITUBERCULATES MONOTREMES
Multituberculata Ptilodus
Monotremata Obdurodon
Ornithorhynchus
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EVOLUTION OF THERIAN MOLARS
Tribosphenic
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THERIAN (TRIBOSPHENIC) MOLARS
(occlusal view)
upper lower
(lateral view)
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TRIBOSPHENIC MOLAR OCCLUSION
Upper
Lower
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Variations on Tribosphenic molar
ectoloph
Dilambdodont (insectivore)
Quadrate or Bunodont (primate)
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MOLARS crowns roots
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Lophodont molar (murid rodents)
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Selenodont molar (artiodactyls)
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Loxodont molar (elephant)
(capybara)
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DENTAL FORMULA Canis lupus
Upper dentition (one side only)
I C P M 3 1 4 2
1 1 4 3 I c p m
Lower dentition (one side only)
3 1 4 2
________
(x 2) 42
3 1 4 3
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DENTAL FORMULAS
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Extreme dentitions
Nine-banded armadillo (Dasypus) simplification
and reduction Common dolphin
(Delphinus) simplification and
multiplication