8/19/2013 1 Topic 5: The Origin of Amniotes Where do amniotes fall out on the vertebrate phylogeny? What are some stem Amniotes? What is an Amniote? What changes were involved with the transition to dry habitats? What are the three main groups of Amniotes? How are Amniote taxa related? (3) – _________ (4) – _________ What is the sister group of Amniota? What taxa comprise the Amniota? Pough et al 2004, Fig 2-1 Where are Amniotes on the vertebrate phylogeny? Benton 1997 Fig 4.21 What are some stem Amniotes? Palaeontological tree: Anthracinosauria, Seymouriamorpha, and Diadectomorpha as extinct outgroups to Amniotes Split between Amniota and Amphibia ~360 Mya Benton 1997 Fig 4.18 “_________________” Anthracinosauria Seymouriamorpha Diadectomorpha Diverse and terrestrial Mainly predators What are some stem Amniotes? Pough et al 2004, Fig 2-1 Synapomorphies ______________ & associated membranes __________ fertilization ____________ maxillary teeth Various other skull and limb characters What is an Amniote? The Amniotic Egg Contains extraembryonic membranes (4): Amnion Chorion Allantois Yolk sac
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8/19/2013
1
Topic 5: The Origin of Amniotes
� Where do amniotes fall out on the vertebrate phylogeny?
� What are some stem Amniotes?
� What is an Amniote?
� What changes were involved with the transition to dry habitats?
� What are the three main groups of Amniotes?
� How are Amniote taxa related?
(3) – _________
(4) – _________
� What is the sister group of Amniota?
� What taxa comprise the Amniota?
Pough et al 2004, Fig 2-1
Where are Amniotes on the
vertebrate phylogeny?
Benton 1997 Fig 4.21
What are some stem Amniotes?
� Palaeontological tree:
� Anthracinosauria, Seymouriamorpha, and Diadectomorpha as extinct outgroups to Amniotes
� Split between Amniota and Amphibia ~360 Mya
Benton 1997 Fig 4.18
� “_________________”
� Anthracinosauria
� Seymouriamorpha
� Diadectomorpha
� Diverse and terrestrial
� Mainly predators
What are some stem Amniotes?
Pough et al 2004, Fig 2-1
� Synapomorphies
� ______________ & associated membranes
� __________ fertilization
� ____________ maxillary teeth
� Various other skull and limb characters
What is an Amniote? The Amniotic Egg
� Contains extraembryonic membranes (4):
� Amnion
� Chorion
� Allantois
� Yolk sac
8/19/2013
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The Amniotic Egg
� __________
� Surrounds embryo
� Forms space filled with amniotic fluid
� ______ exchange
� _________ embryo
� Dessication
� Concussion
� Chorion
� Allantois
� Yolk sac
The Amniotic Egg
� Amnion
� ___________
� Outer-most membrane
� Forms placenta in placental mammals
� Allantois
� Yolk sac
The Amniotic Egg
� Amnion
� Chorion
� ____________
� Sac formed from posterior part of GI tract
� Collects ___________ during development, growing as it fills
� Involved in formation of _______________ in placental mammals
� Yolk sac
The Amniotic Egg
� Amnion
� Chorion
� Allantois
� _____________
� Filled with yolk, which is the nutrient source for the embryo