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Zoology 1 > Biodiversity 8: The mammals > Flashcards

Biodiversity 8: The mammals Flashcards

1
Q

Describe the key features of the class mammalia

A

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

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2
Q

Describe some anatomical features of mammals

A

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

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3
Q

Describe the 2 types of mammalian hair

A

Thin soft under hair - insulation
Thick long guard hair - protection

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4
Q

Give some examples of modified mammalian hair and their functions.

A

Porcupine quills → protects against predators
Pangolin scales →protects against predators and water loss
Puma whiskers → sensory
Rhino horn → matted hair, protection

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5
Q

What are mammalian ossicles originally made from?

A

The bones originally in the jaw of the reptiles = malleus and incus

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6
Q

Why is having 3 ossicles an adaptation?

A

Sound detection and distinction much more evolved

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7
Q

What are the 4 types of mammalian teeth?

A

Incisors
Canines
Premolars
Molars

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8
Q

What are incisors used for?

A

cutting, shearing

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9
Q

What are canines used for?
In which mammals are they found?

A

piercing, ripping (absent in herbivores, dominant in carnivores)

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10
Q

What are premolars used for?

A

slicing, crushing

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11
Q

What are molars used for?

A

grinding (bone or coarse vegetation)

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12
Q

What is the dental formula?

A

I-C-P-M

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13
Q

What is the dental formula in placental mammals?

A

3-1-4-3/3-1-4-3

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14
Q

What is the dental formula in humans?

A

2-1-2-3

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15
Q

Which adaptations allowed Mesozoic mammals to survive the extinctions of the Cretaceous and radiate?

A

hair and fat provide insulation

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16
Q

Describe the prototheria

A

‘one opening’
Reptilian characteristics:
Egg laying (egg is reptilian in structure)
Cloaca
Mammalian characteristics:
Hair
Mammaries

17
Q

What are the 2 forms of prototheria?

A

Platypus
Echidna - spiny anteater

18
Q

Describe the platypus

A

aquatic life
Webbed feet, thick fur, no ears
Bill for feeding on invertebrates (convergent evolution)
Find prey using electric pulses

19
Q

Describe the echidna

A

Long snout
Sticky tongue
Heavy claws

20
Q

Describe the metatheria

A

Egg contains yolk, shell membrane
Embryo nourishes mostly by yolk then placenta later on
Short gestation, young altricial <1% mother weight
Young are completely dependent on mother for 1st month
Young have strong forelimbs and claws, climb into marsupium (pouch) where mammaries are located
E.g Koalas, Virginia Opossum, Red Kangaroo

21
Q

Which clade do marsupials belong to?

A

Metatheria

22
Q

Which clade do placental mammals belong to?

A

Eutheria

23
Q

Describe the Eutheria

A

al mammals - Eutheria
Complete development in uterus
Most extant orders originated 50-70 mya
Phylogenetic relationships between orders are difficult to resolve as they radiated rapidly

24
Q

What are the 4 major lineages in the Eutheria?

A

Afrotheria e.g elephants
Xenarthra e.g sloths
Laurasiatheria e.g moles, bats, cats
Euarchontoglires e.g rabbits, mice

25
Q

Give some examples of species that belong to afrotheria

A

Elephants
Manatees and dugongs

26
Q

Give some examples of species belonging to xenarthra

A

Sloths, anteaters, armadillos
- have reduced or no teeth

27
Q

Give some orders belonging to laurasiatheria

A

Insectivores - moles, shrews, hedgehogs
Bats
Carnivores - cats, dogs, seals
Cetaceans - whales, dophins
Artiodactyles - sheep, pigs, deer
Perissodactyls - horses, rhinos

28
Q

Which order is considered the most primitive of the Laurasiatheria

A

Insectivores

29
Q

Describe carnivores specialised dentition

A

Specialised for piercing (incisors) and slicing (carnassial pair)

30
Q

Describe the artiodacytes

A

sheep, pigs, deer
Even toed ungulates
Bunodont or selenodont teeth
Elaborate ruminant stomach to digest cellulose (e.g cows chew twice)
Weaponry evolved in many
- Tusks
- Antlers
- Horns

31
Q

Describe the Perissodactyls

A

horses, rhinos
Odd toed ungulates
Lophodont grinding molars and incisors for cropping vegetation
Simple single stomach

32
Q

Which orders belong to Euarchontoglires?

A

Lagomorphs
Rodents

33
Q

Describe the lagomorphs

A

Rabbits, hares
2 pairs of rootless incisors
Rootless molars, high crowned (hypsodont)

34
Q

Describe the rodents

A

Most specious mammals
Rootless incisors, hypsodont molars
Most pass food twice (caecotrophy)

Zoology 1 (26 decks)

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