Vertebrates 4 - Bird

challenges of birds and how they overcame them

occupying extreme environments - thermoregulation

get into air! - feathers/betterlungs/lighter bones

who did birds evolve from

reptilian ancestors who were dinos (therapods)!

shared charecteristics

• parental care

• heart/feet/bones

• bipedal

• feathers!

**specifically from archaeopteryx #arcteryx

approx how many transitions to flight were there

4: birds, bats, insects, pterosaurs *convergent evolution!

Archaeopteryx ‘anceint wing’ when, what traits

150 mya

12+ fossils

crow sized

feathers and wings! (avian charecteristics)

teeth and boney tale (non avian charecteristic)

Bird (Aves) Important Traits

• 9600 species

• amniotes

• endothermic

• 4chambered heart

• feathers

• most fly

• diverse beaks and claws - both made for what the forage on/their environment

types of thermoregulators (4)

• endotherms - produce own heat w metalbolic processes - metabolic rate varies to maintain this

• ectotherms - absorb external heat - metabolism increases exponentially with increase in temp and then they can do more (turtles slow in cold)

• homeotherms - constant temp

• heterotherms - variable temp

A CONTINUM!

3 Mechanisms for Thermoregulation

• Behavioural

• Physiological

• Physical

Behavioural Thermoregulation

everyone does it

• lizards moving through the day

• penguins huddle

Physiological Thermoregulation

human thermostat in hypothalmus

• sweating/shivering

• negative feedback loop

Physical Thermoregulation

• fur/fat

  • SA difference (evolve to be smaller in colder climates)

Purpose of bird specialized Resperation

need more o2 to be flying (lots of energy) and to be an endotherm @ such heights (30k +) and intensity

Unidirectional Resperation

have many air sacs (8-9) @anterior and posterior

2 breaths

1. all drawn into posterior

2. then drawn into anterior

3. then propelled out through nares

convergent evolution

similarites due to common environment and dont have common ancestor [can delete]

Adaptations for flight

• hollow bones

• sternum enlarged/keeled for large pectoral muscles

• feathers (originally for warmth)

Feather Functions NOW

• lining nests

• sensory structures

• insulatoin

• flight

composed of b keratin that comes from scales!

2 Evolution of Flight Theories

• ground up

  • somewhat more supported (more closely related to running animals, amount of species that glide and dont fly)

• tree down