Synapsida Lecture (Amniote cont.) Flashcards Preview

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Flashcards in Synapsida Lecture (Amniote cont.) Deck (54)
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1

synapsids have (temporal)

one pair temporal skull opening behind orbits

2

synapsids = first lineage to

diverge from ancestral amniotes (sister lineage to class w/ other amniotes "diapsids")

3

synapsids include

mammals (only extant lineage)

4

Evolution of mammals lineages (3)

pelycosaurs, therapsids, cynodonts

5

Pelycosaurs are the

most basal synapsids

6

pelycosaurs radiation

into diverse lineages (carnivores & herbivores)

7

pelycosaurs extinct

by end of paleozoic

8

pelycosaurs monophyletic or paraphyletic?

paraphyletic (therapsid lineage emerged w/in a carnivorous pelycosaur lineage)

9

Therapsids radiation

into diverse lineages (carnivores & herbivores)

10

therapsids persisted

into mesozoic

11

therapsids monophyletic or paraphyletic?

paraphyletic (cynodont lineage emerged w/in therapsid lineage)

12

Cynodonts exhibited (2)

- heterodonty = differentiation of tooth types
- changes in jaw musculoskeletal structure

13

cynodont jaw musculoskeletal structure changes:

- enlargement of dentary & reduction of posterior bones of mandible
- evolution of masseter muscle = allows lateral jaw movements

14

cynodonts monophyletic or paraphyletic?

paraphyletic (mammal lineage emerged w/in cynodont lineage)

15

Early mammals arose

>200 mya (Triassic)

16

early mammals exhibited (2)

- diphyodont deviation = teeth replaced 1x in life
- new jaw joint btwn squamosal & dentary = quadrate & articular incorporated (w/ stapes) into middle ear

17

early mammal jaw & joint evolution

w/ time --> decrease in quadrate & articular, increase in dentary

18

what forms the jaw joint?

quadrate, squamosal, & articular

19

early mammals had ____ & were likely _________

hair, endothermic

20

early mammals also had a

secondary palate = separates feeding & breathing pathways / permits suckling by young

21

mammal hair

- unique to mammals
- dead cells w/ keratin
- epidermal structure

22

derivatives of mammal hair (2)

- vibrassae (mechanoreception)
- spiny armor (porcupines, hedgehogs, & echidnas have all independently evolved spines derived from hair) (protection against predators)

23

great morphological variation through dental evolution is due to

feeding specializations

24

mammals have greatest variety of

glands among vertebrates

25

mammal glands (4)

- sweat glands (evaporative cooling)
- scent glands (communications (attracting mates, territorial marking)) (defense (skunks))
-sebaceous glands (expel sebum - keep hair/skin pliable)
- mammary glands (possessed by females (rudiment in males)) (milk secreted from glandular tissue to feed young)
*humans --> adipose tissue around glandular tissue forms breasts (unique & plays role as sexual signal)

26

mammary glands are homologous to

sweat glands

27

Mammalia =

Monotremata + Metatheria + Eutheria

28

monotremata reproduction

oviparous (lay & incubate eggs)

29

metatheria reproduction

vivaporous w/ altricial young (born at early developmental stage) (babies w/ eyes that can't open yet)

30

metatheria aka

"marsupials"