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Biol204 > Skulls - Components, jaws > Flashcards

Skulls - Components, jaws Flashcards

1
Q

Function of branchial arches III-VII in most fish

A

Support gills

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2
Q

Who has modified hyostyly?

A

Actinopterygii

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3
Q

What does the splanchnocranium form?

A

7 branchial arches & their derivatives (jaws, middle ear bones)

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4
Q

What feeding method do actinopterygiians use?

A

Suction feeding

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5
Q

Embryonic origin of splanchnocranium

A

Neural crest cells (-> cartilage, ossifies in most teleostomi)

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6
Q

Describe branchial arches III-VII

A

Made of 5 pieces (usually)

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7
Q

Precise functions of dermatocranium

A
  • Cover chondrocranium & brain (dorsal, ventral)
  • Cover & protect gills (opercular bone)
  • Cover parts of jaw splanchnocranium
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8
Q

Describe modified hyostyly

A

Quadrate: Articulation point of upper jaw, not fused to chondrocranium
Articular: Articulation point lower jaw
Hyomandibula & symplectic bone: suspend jaws from chondrocranium
-> Many joints = highly kinetic (suction feeding)

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9
Q

Describe paleostyly

A

All branchial arches used to support gills; no jaws

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10
Q

Lower jaw bone in teleostomi

A

Dentary (encases Meckel’s cartilage except for ossified back portion; part of dermatocranium)

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11
Q

General function of dermatocranium

A

Form hard, protective structures

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12
Q

Function of branchial arches III-VII in amniotes

A

Form cartilage around trachea & larynx

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13
Q

Who has a dermatocranium?

A

Teleostomi (Osteichthyes, Tetrapods, not Agnathans, Chondrichthyes b/c no bone)

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14
Q

Who has paleostyly?

A

Agnathans

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15
Q

Adaptations of actinopterygiian skull to feed by biting prey

A

2° loss of cranial kinesis by bone fusion to provide strength

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16
Q

Upper jaw bones of teleostomi

A

Premaxilla, maxilla (dermatocranium)

17
Q

Embryonic origin: chondrocranium

A

Neural crest cells, mesodermal mesenchyme

18
Q

Describe Autostyly

A

Palatoquadrate: Upper jaw, fused to chondrocranium
Meckel’s cartilage: lower jaw
Hyoid arch: gill support

19
Q

Embryonic origin & final tissue type: Dermatocranium

A

Mesenchyme from dermatome epimere mesoderm -> Dermal bone

20
Q

Who has hyostyly?

A

Most sharks

21
Q

Describe metautostyly

A

Quadrate (upper) and articular (lower) form jaw joint; quadrate fused or articulates w/ chondrocranium; II -> columella in middle ear (not for jaw suspension)

22
Q

Who has craniostyly?

A

mammals

23
Q

Describe adaptations of actinopterygiian skull for suction feeding

A
  1. Maxilla connected loosely to chondrocranium & lower jaw (rotates forward as jaw opens)
  2. Premaxilla connected loosely to maxilla (can be projected forwards faster)
  3. Chondrocranium rotates at spinal connection (rises as lower jaw drops)
  4. Hyoid apparatus: struts in buccal cavity floor, pulled perpendicular to push out lateral walls as mouth opens
    => Creates suction
24
Q

How does hyostyly affect feeding?

A

Allows jaws to swing forwards to open wider & for teeth to contact prey at same time (good for grabbing slippery prey)

25
Q

Regions of brain protected by chondrocranium

A

All vertebrates: ventral, lateral, posterior

Agnathans & chondrichthyans: dorsal (-> forms entire braincase)

26
Q

Chondrocranium tissue type

A

Cartilage: initially, all; remains in agnathans, chondrichthyes
Bone (replacement): teleostomi

27
Q

Who has metautostyly?

A

Amphibians, sauropsids

28
Q

Who has autostyly?

A

Holocephali (ratfish), dipnoi (lungfish)

29
Q

Describe hyostyly

A

Palatoquadrate: Upper jaw, not fused to chondrocranium
Meckel’s cartilage: lower jaw
Hyomandibula: Forms swinging bridge attaching jaw to chondrocranium
-Spiracle: reduced pharyngeal slit between mandibular & hyoid arches

30
Q

Describe amphistyly

A

Palatoquadrate: upper jaw, held to chondrocranium by ligament
Meckel’s cartilage: lower jaw
Hyomandibula: stabilizes back of palatoquadrate, also gill support

31
Q

3 components of the skull

A

Chondrocranium, splanchnocranium, dermatocranium

32
Q

Describe craniostyly

A 
Entire upper jaw fused to chondrocranium
Dentary (lower) articulates with squamosal (upper)
Jaws entirely dermatocranium
I & II in middle ear
Quadrate -> Incus
Articular -> Malleus
Hyomandibula -> Stapes
33
Q

Who has amphistyly?

A

6-gilled sharks

Biol204 (13 decks)

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