MAMMALS Flashcards
Mammalia is found in the class (a). This quality refers to singular fenestra postorbital which has later (b) with the orbit. ‘Non mammalian reptiles’ have retained the (c).
a) Synapsida
b) merged
c) hole
There was a gradual shift from ___ to ____, beginning with the pelycosaurs, a __phyletic group.
ectothermy to endothermy
- paraphyletic
Pelycosaurs have ___ teeth
homodont
What did we see in the paraphyletic non cynodont therapsids?
more upright and mobile
Evolutionary breakthrough in the cynodont therapsids
The secondary palate meant that air could travel to the back of the mouth from the nostrils rather than through it – this makes it easier to chew and breathe!
Pelycosaur ((a) fenestra)
became
Non- Cynodont therapsids ((b) fenestra)
became
Cynodont therapsids ( formation of (c) arch )
became
MAMMALS (with a (d) of fenestra and orbit)
a) small
b) large
c) zygomatic
d) merge
What did the merge of fenestra and orbit lead to?
- jaw muscle specialisation
- thinner areas open and muscles attached to strengthen edges
- down growths provided further anchorage
- increased brain protection
- masseter, temporalis
- zygomatic arch
What did primitive tetrapod lower jaw look like?
Primitive mammalia? Originally evolved for what function?
- many bones
- fusion into one bone
- transmitting vibrations
Secondary palate allowed the development of (a) behaviour. Involving what 2 seals?(b)
a) suckling
b) tongue against roof prevents food reaching pharynx
- between epiglottis and soft palate
- to only allow air into trachea
Mammals only have 2 sets of teeth in lifetime, what is this called? Meaning of heterdont? Meaning of occlusion?
diphydonts
- different types of teeth
- upper and lower teeth alligned
What is hair made from?
keratin
Thecodont stance vs Pelycosaur stance?
Pelycosaur have sprawling lizards limbs but thecodonts are below body
Loss of ribs from posterior vertebrae facilitates what ?
greater locomotion
Metatheria are the ___
marsupials
Eutheria are the ___ mammals
placental
