Biodiversity 8: The mammals Flashcards
Describe the key features of the class mammalia
Endothermic vertebrates
Possess hair made of keratin, with fat = insulation
Skin glands inc mammary (modified sweat gland)
4 chambered heart → needed to support high metabolic rate
Describe some anatomical features of mammals
Limbs carried beneath body
Synapsid skull (1 fenestra) with large braincase
Jaw consists of a single bone
Ear comprises 3 ossicles derived from jaw bones
Describe the 2 types of mammalian hair
Thin soft under hair - insulation
Thick long guard hair - protection
Give some examples of modified mammalian hair and their functions.
Porcupine quills → protects against predators
Pangolin scales →protects against predators and water loss
Puma whiskers → sensory
Rhino horn → matted hair, protection
What are mammalian ossicles originally made from?
The bones originally in the jaw of the reptiles = malleus and incus
Why is having 3 ossicles an adaptation?
Sound detection and distinction much more evolved
What are the 4 types of mammalian teeth?
Incisors
Canines
Premolars
Molars
What are incisors used for?
cutting, shearing
What are canines used for?
In which mammals are they found?
piercing, ripping (absent in herbivores, dominant in carnivores)
What are premolars used for?
slicing, crushing
What are molars used for?
grinding (bone or coarse vegetation)
What is the dental formula?
I-C-P-M
What is the dental formula in placental mammals?
3-1-4-3/3-1-4-3
What is the dental formula in humans?
2-1-2-3
Which adaptations allowed Mesozoic mammals to survive the extinctions of the Cretaceous and radiate?
hair and fat provide insulation