Lecture 6 Flashcards
What is Lepidosauria?
subset of diapsida that includes sphenodontida (tuatara) and squamata
What is the Single species of sphenodontida? why are they in danger?
Tuatara - very slow reproductive rate (females mate once every four years and incubation lasts 11-16 months
What are the three major groups of squamata?
serpentes, lacertilia and amphisbaenia
What is archaeopteryx?
transitional fossil between reptiles and birds which has traits of both - from late jurassic (150mya)
What is different between archaeopteryx and modern birds?
- long bony tail has compressed in birds
- head became much lighter
- finger bone fused together
- bone structures became more compact and long extremities are replaced with feathers
- large keel in modern birds because of muscle attachment
What are adaptations for flight in birds?
- strong keel supports flight muscles
- hollow bones
- feathers provide light rigid flight surfaces
- pygostyle supports tail feathers for breaking and steering
- hand bones fused to strengthen wing
What did birds evolve from?
theropod dinosaurs in late jurassic
What are two theories surrounding the evolution of flight and wings?
Tree down vs. ground up, or arboreal vs. cursorial
Theropod dinosaurs are part of what kind of dinosaurs? What is their major characteristic?
saurischian dinosaurs - saurischian pelvis
What is protarchaeopteryx?
Fossil discovered from early jurassic period. It was a theropod dinosaur with wing feathers and tail feathers.
What is so important about the protarchaeopteryx?
shows that feathers evolved before flight
Why might protarchaeopteryx have had feathers?
- mating displays
- thermoregulation
- could help get lift when jumping to attack prey
why is the troodontid dinosaur fossil important?
shows dinosaur in a bird-like sleeping posture which suggests they were endothermic
What is important about the microraptor gui?
it is a four winged dinosaur fossil that may have been the intermediate step on the way to two winged flight
- most likely a gliding animal
