BIRDS Flashcards
Early birds are in suborder ____ and class ___.
Therapoda
Aves
Between the late triassic and end cretaceous what was the transition in giant bird like dinosaurs?
LATE TRIASSIC
- long tailed and small wingspan
- ramphorhynchoid pterosaurs
END CRETACEOUS
- no teeth
- giant wingspans
Potential aerial niches
- diving like a gannet
- open billed wading
- skimming to eat fish
What is the evidence that birds emerged from theropod dinosaurs? Turns out this is the __ answer.
- hips
- bipedalism
- breast bone similar to bird sternum (wishbone)
DROMEOSAURS had a (a) and were (b).
furcula
- theropods
Why were crocodylomorphs suggested as bird ancestors?
- skull similarity in the quadrate and inner ear structures
Archaeopteryx has what similarities with birds?
What differences ?
- Wings and feathers
- Teeth, fingers with claws and a bony tail
Why did Helmann reject the idea that birds emerged from therapods?
put it down to convergent evolution
What disproved the theory that birds emerged from crocodylomorphs?
protein analysis of collagen a1 and a2 were different in 89 amino acids
Describe
a) the arboreal theory of flight evolution
b) evidence for the arboreal theory
a) from the trees down, that flight was a sequential process from leaping, to gliding, to parachuting to flight
b) many aves ancestors show adaptations for climbing in claw form
Birds are the ___ archosaur lineage to succesfully exploit an aerial niche.
second
Describe
a) the cursorial theory of flight evolution
b) evidence for this
c) evidence against this
a) ground up- jumping became more advantageous so wings evolved to assist balance and developed flight
b) the hind limbs in dromeosaurs
c) Archaeopteryx wings were not strong enough
- feathers were probably a hindrance
- requires huge ground speed
What is a keel?
extension of sternum, acts as anchoring point for flight muscles
What is a pygostyle
a reduced tail
What is the pelvic girdle a fusion of?
- pubis, isthmus, ilium
