traditional view: insectivorans represent primitive eutherian stock
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Traditional view: Insectivorans represent primitive eutherian stock. Original classification of Insectivora (mid-1800s): Elephant shrews Treeshrews Flying lemurs Erinaceidae Solenodontidae Soricidae Talpidae Chrysochloridae Tenrecidae. Insectivora. - PowerPoint PPT PresentationTRANSCRIPT
Original classification of Insectivora (mid-1800s):
Elephant shrews
Treeshrews
Flying lemurs
Erinaceidae
Solenodontidae
Soricidae
Talpidae
Chrysochloridae
Tenrecidae
Insectivora
Original classification of Insectivora (1866):
Elephant shrews
Treeshrews
Flying lemurs
Erinaceidae
Solenodontidae
Soricidae
Talpidae
Chrysochloridae
Tenrecidae
Cecum present: Order Menotyphla
Cecum absent: Order Lipotyphla
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)
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?
1. Maxillary expansion in orbit (preventing contact of palatine & frontal)
maxilla
palatine
frontal
Hedgehog
Opossum
BUT, golden moles, some tenrecsdon't have expanded maxilla.
3. Reduced jugal
BUT, small jugals in hedgehogs mayrepresent ancestral condition ineutherians.
Jugal reduction in other lipotyphlansnot well understood.
Tenrecs, golden moles, hedgehogs, solenodons (& some primates, bats, rodents...)
shrews,some moles
some moles
5. Reduced pubic symphysis
connected with cartilage only; no bony fusion
ilium
pubis
BUT, reduced symphysis foundin most fossorial mammals.
"Reduced" difficult to categorize.
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.
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!
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’)
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: