traditional view: insectivorans represent primitive eutherian stock
TRANSCRIPT
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Traditional view: Insectivorans represent primitiveeutherian stock.
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Original classification of Insectivora (mid-1800s):
Elephant shrews
Treeshrews
Flying lemurs
Erinaceidae
Solenodontidae
Soricidae
Talpidae
Chrysochloridae
Tenrecidae
Insectivora
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Original classification of Insectivora (1866):
Elephant shrews
Treeshrews
Flying lemurs
Erinaceidae
Solenodontidae
Soricidae
Talpidae
Chrysochloridae
Tenrecidae
Cecum present: Order Menotyphla
Cecum absent: Order Lipotyphla
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Original classification of Insectivora (1900s):
Elephant shrews: Order Macroscelidea
Treeshrews: Order Scandentia
Flying lemurs: Order Dermoptera
Erinaceidae
Solenodontidae
Soricidae
Talpidae
Chrysochloridae
Tenrecidae
Cecum absent: Order Lipotyphla (but use of “Insectivora” continued)
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Proposed synapomorphies (Butler 1988):
1. Maxillary expansion in orbit2. Mobile proboscis3. Reduced jugal4. Hemochorial placenta5. Reduced pubic symphysis6. Cecum absent
Lipotyphla
Late 1900s: Is Lipotyphla a natural group?
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1. Maxillary expansion in orbit (preventing contact of palatine & frontal)
maxilla
palatine
frontal
Hedgehog
Opossum
BUT, golden moles, some tenrecsdon't have expanded maxilla.
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2. Mobile proboscis
present insome...
absent in others...and PRESENT inmany non-lipotyphlans
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3. Reduced jugal
BUT, small jugals in hedgehogs mayrepresent ancestral condition ineutherians.
Jugal reduction in other lipotyphlansnot well understood.
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Tenrecs, golden moles, hedgehogs, solenodons (& some primates, bats, rodents...)
shrews,some moles
some moles
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5. Reduced pubic symphysis
connected with cartilage only; no bony fusion
ilium
pubis
BUT, reduced symphysis foundin most fossorial mammals.
"Reduced" difficult to categorize.
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smallintestine
largeintestine
Cecum:
1st part of large intestine
2 primary functions:
1) Microbial breakdown of partiallydigested food
2) Recover moisture fromdigesting food
In general, faunivores have simplegut tubes (animal prey easier todigest).
Ancestral eutherian conditionuncertain.
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Herbivore Carnivore Insectivoran
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Whales & dolphins
Artiodactyls
Artiodactyls
Carnivorans
Pangolins
Perissodactyls
Bats
Solenodons
Moles
Shrews
Hedgehogs
Primates
Treeshrews
Colugos
Lagomorphs
Rodents
Xenarthrans
Golden moles
Tenrecs
Elephant shrews
Aardvarks
Dugongs & manatees
Hyraxes
Elephants
DNA sequence data:Lipotyphla is non-monophyletic!
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Laurasia
Gondwana
Plate tectonics separate N. & S. supercontinents
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Whales & dolphins
Artiodactyls
Artiodactyls
Carnivorans
Pangolins
Perissodactyls
Bats
Solenodons
Moles
Shrews
Hedgehogs
Primates
Treeshrews
Colugos
Lagomorphs
Rodents
Xenarthrans
Golden moles
Tenrecs
Elephant shrews
Aardvarks
Dugongs & manatees
Hyraxes
Elephants
Southern hemisphere radiation(‘Afrotheria’)
Northern hemisphere radiation(‘Laurasiatheria’)
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Whales & dolphins
Artiodactyls
Artiodactyls
Carnivorans
Pangolins
Perissodactyls
Bats
Solenodons
Moles
Shrews
Hedgehogs
Primates
Treeshrews
Colugos
Lagomorphs
Rodents
Xenarthrans
Golden moles
Tenrecs
Elephant shrews
Aardvarks
Dugongs & manatees
Hyraxes
Elephants
Afrotheria Laurasiatheria
Laurasiatheria
Afrotheria
Parallel adaptive radiations on N. & S. supercontinents: