Birds And Mamals Flashcards
Where did birds evolve from
Therapod dinosaurs
What are the key traits of birds
Aminote eggs
Highly modified limbs
Feathers
Lungs
4 chambered heart
Beak without teeth
Hollow air filled bones
Endotherms
Large cerebellum for flight
Where did feathers come from
Feathers may have evolved from enlarged scales. Birds still have feathers present on their legs and feet.
What skeletal modifications do birds have
Pentadactyl limbs highly modified into wings
Hollow bones to reduce weight for flight
Enlarged sternum (keel) for powerful flight muscles to attach too
Describe the bird respiratory system
The lungs are surrounded by an anterior sack and a posterior sack. The sacks allow air to keep moving in one direction, so birds do not need to pump air in and out of their lungs. This supports the birds high metabolic rate, although no gas exchange occurs inside the sacks.
How many bird orders are there
28
What are the two groups that birds aes divided into
Paleognaths (ratites)
Neognaths
What groups are contained within the neognaths
Galloanserae (ducks, chickens, landfowl and waterfowl)
Neoaves (all other birds)
What are the main characteristics of mammals
Three bones in middle ear
Jaw is made up of a single bone
Mammalian glands
Endotherms
Covered in fur
Hetrodonts
What are the main skeletal changes in mammals
Formation of a second palate which allows for the movement of air whilst eating
Heterodont teeth with lots of different specialisations
Turbinate bones that retain body heat
How is the posture of galloping mammals beneficial
When most reptiles walk they move from side to side which compresses their lungs as they move. Thus only allows for quick bursts of anaerobic movement
Mammals have their feet underneath them which means that their movements support breathing.
What are the functions of hair in mammals
Insulation
Touch
Camouflage
Communication
How are mammals fertilised and how does the embryo develop
Internal fertilisation
Developing embryo is contained in the uterus
Embryo is within an amniotic sac homologous with that of reptiles and birds
What are the different groups of mammals
Monotremes (platypus and echidnas)
Metatheria (marsupials)
Eutheria (placental mammals)
What was the K-Pg mass extinction event
Occurred 66 million years ago
Caused large changes in climate
Wiped out not therapod dinosaurs
Provided a large opportunity for survivors to fill in the now open niches
