Bird evolution

Question 1

Defining bird characteristics

Answer 1

Warm blooded 
4 chambered heart 
Feathered
Toothless beak
Hollow bones
Visually guided
Egg laying 
2-legged 
Flying

Question 2

Bird like features in dinosaurs

Answer 2

Long spindly legs 
Long neck
Small head with large eyes 
Pubic bone rotation 
Fused clavicles>furcula 
Outwards arm rotation

Question 3

Distinctly dinosaur features

Answer 3

Clawed hands
Teeth
Bulky long tail

Question 4

Missing link between feathered dinosaurs and modern birds

Answer 4

Late Jurassic - early Cretaceous
Archaeopteryx
Probably diurnal
Not necessarily the ancestor of modern birds
Fossil found 2 years after Darwin David we should look for incremental fossils

Question 5

Confuciusornithidae

Answer 5

120-125MYA, 6 species

More bird like early bird

Question 6

Enantiornithes

Answer 6

Cretaceous
40-50 species
Global dist
Variety of body plans

Question 7

Vestigial wing claws

Answer 7

Thought early birds had 3 claws on wings
Some evidence in modern birds e.g. Hoatzin have 2 claws on wings they use to get chicks back in nest if leave due to predation

Question 8

Dissenting views

Answer 8

• birds aren’t direct descendants but an evolutionary offshoot. They came from earlier ancestors than dinosaurs.
• differences in developmental origin of wing claws. > however small genetic changes could cause this.
• feathers aren’t formed in the same way. Convergent evolution not descent

However overall thought they form dino’s