[E] Reptiles

• Fluid-filled sac covering embryo

  Amnion
• Outermost covering of the embryo

  Chorion
• Vascularized sac for gas exchange

  Allantois
• Two main amniote lineages:

  1. Sauropsida

  • Parareptilia
  • Eureptilia

  1. 2. Synapsida

  • Therapsids
  • Modern mammals
• Identify the amniote skull types:

  A) Anapsid

  B) Diapsid

  C) Euryapsid

  D) Synapsid

  
• Sauropsida: Reptilia (Reptiles) 

  • Only includes Parareptilia and Eureptilia 
  • Mesosaurs with fully aquatic lifestyle 
  • Viviparous
  • Parareptilia (extinct) 
  • Eardrum supported by squamosal and retroarticular process 
  • Unique articulation of digits with ankle bones
  • Eureptilia - true reptiles
  • Archosauromorpha - dinosaurs, birds
  • Lepidosauromorpha - snakes, lizards
• Archosauromorpha: Crocodylomorpha

  • Pseudosuchian archosaurs
  • Crocodyliformes as surviving lineage 
  • Crocodiles, alligators, gharials, caimans, gavials (Crocodylia)
  • Various lifestyles 
  • Gracile terrestrial forms 
  • Aquatic predators (all extant members) 
  • Skull and ankle joint similar to thecodonts 
  • Teeth set in individual sockets
  • Unique ankle design for bipedal upright posture
• Archosauromorpha: Aves (birds)

  • Feathers - theory: used for thermoregulation
  • Second most diverse vertebrate group
  • Most closely related to crocodylomorphs
  • Shell-encased eggs
  • Similar bone and muscle structure
  • Placed within saurischia 
  • Similarities in hip, wrist, wishbone structures 
  • Development of feathers 
  • First arose in coelurosaurs