BIOL 204 > Skeleton > Flashcards

Skeleton Flashcards

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1
Q

braincase

A
  • region of the skull that immediately surrounds the brain
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2
Q

what forms the braincase in different taxa (2)

A
  • agnatha + chondrichthyes: only chondrocranium

- teleostomi: chondocranium (ventral) + dermatocranium (dorsal)

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3
Q

chrondrichthye jaw composition

A

splanchnocranium:
- palatoquadrate (upper)
- Meckel’s cartilage (lower)

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4
Q

teleostomi jaw composition

A 
dermatocranium
- premaxilla, maxilla
splanchnocranium
- quadrate (upper)
- articular (lower)
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5
Q

feeding mechanisms (4)

A
  • prehension
  • durophagy
  • mastication
  • suction feeding
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6
Q

feeding mechanism: prehension (2)

A
  • use jaws and teeth for grasping and holding prey

- generally swallow prey whole

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7
Q

feeding mechanism: durophagy

A
  • use powerful bite to crush hard food
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8
Q

feeding mechanism: mastication (3)

A
  • many mammals
  • jaws and teeth used for chewing food
  • rhythmic and repetitive movements of the jaw to grind food
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9
Q

suction feeding (2)

A
  • aquatic vertebrae

- rapid expansion of the buccal cavity and pharynx generates sudden decrease in pressure that sucks prey into the mouth

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10
Q

akinetic skull (2)

A
  • skulls with only one mobile joint: the joint between the upper and lower jaws
  • only lower jaw is mobile, while upper jaw is immobile relative to the braincase
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11
Q

cranial kinesis (2)

A
  • movement of the upper jaw relative to the braincase

- requires at least one mobile joint between the braincase and the upper jaw

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12
Q

kinetic skull

A
  • skulls with more than one mobile joint
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13
Q

paleostyly

A
  • all pharyngeal arches support the gills
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14
Q

autostyly (2)

A
  • palatoquadrate attached directly and firmly to the braincase
  • hyoid arch not involved in jaw suspension
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15
Q

hyostyly (2)

A
  • jaws suspended from the braincase by the hyomandibula, which forms a swinging bridge that allows jaws to protrude (swing forward)
  • mobile joint between hyomandibula and braincase, and between hyomandibula and jaws
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16
Q

hyostylic jaw suspension and feeding (2)

A
  • allows for protrusion: pendulum-like swing forward allows the mouth to open wider and close faster
  • allows upper and lower jaw to strike prey at same time, gripping prey securely
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17
Q

chondrichthyes: hyoid apparatus (2)

A
  • ventral elements of the hyoid arch

- support the tongue and the floor of the mouth

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18
Q

spiracle (2)

A
  • reduced pharyngeal slit between the hyoid and mandibular arch
  • opening for H2O
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19
Q

modified hyostyly (3)

A
  • jaw is attached to the braincase by the hyoid arch, especially the hyomandibula along with several other bones
  • several mobile joints, making the jaw extremely kinetic
  • mobile joint between upper and lower jaw is between the quadrate and articular
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20
Q

modified hyostyly jaw suspension: feeding mechanism (2)

A
  • catch their prey mainly using suction feeding

- kinetic structure allows for variety of feeding mechanisms: powerful bite

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21
Q

modified hyostyly jaw suspension: mobile joints

A

mobile joints between:

  • maxilla and chondrocranium
  • premaxilla and chondrocranium
  • maxilla and premaxilla
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22
Q

modified hyostyly jaw suspension: how do the mobile joints affect the jaw (2)

A
  • make upper jaw highly kinetic, allowing for protrusion of the upper jaw
  • when lower jaw is depressed, maxilla/premaxilla rotate forward, allowing mouth to open extremely wide
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23
Q

actinopterygii: hyoid apparatus (3)

A
  • formed by ventral elements of the hyoid arch + other arches
  • supports tongue and floor of mouth
  • forms lateral struts within the floor of the buccal cavity
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24
Q

modified hyostyly jaw suspension: lateral struts of hyoid apparatus (2)

A
  • push lateral walls of buccal cavity outwards when mouth is open
  • greatly expands volume of the buccal cavity, generating suction
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25
modified hyostyly jaw suspension: powerful bite (2)
- premaxilla must resist forceful impact of snapping shut on prey and provide solid foundation for lower jaw to close against - some: premaxilla loses mobility and fuses to chondrocranium to increase strength and rigidity of upper jaw
26
actinopterygii: pharyngeal jaws (3) - definition - composition - general features
- second pair of jaws located in the pharynx - composed of modified elements of posterior pharyngeal arches - have teeth and highly kinetic
27
pharyngeal jaw functions (4)
variety of functions: - slicing food - crushing hard food - pulling food from buccal cavity into esophagus - separating inedible material out of food before swallowing
28
metautostyly (2)
- jaws attached to braincase directly by quadrate bone | - mobile joint between articular and quadrate bone
29
metautostyly: hyomandibular (3)
- not involved in jaw suspension - reduced to the columella, a small, thin bone of the inner ear - vibrates to amplify sound
30
unmodified metautostyly (2)
- quadrate is firmly attached to the braincase | - the quadrate is not mobile
31
modified metautostyly (3)
- mobile joint between quadrate and braincase - quadrate forms a swinging bridge, allowing lower jaw to protrude and increasing lower jaw range of motion - metautostyly with streptostyly
32
craniostyly (3)
- entire upper jaw attaches firmly to braincase - both upper and lower jaws formed completely of dermatocranium - dentary and squamosal bones
33
craniostyly: dentary bone
- lower jaw is composed of single dermal bone
34
craniostyly: squamosal bone (2)
- dermal bone of the braincase | - articulates with dentary bone to form the mobile joint between the upper and lower jaws
35
craniostyly: bones of the middle ear (3)
- quadrate reduced to the incus, articular reduced to the malleus - hyomandibula reduced to stapes - function to trasmit sound waves from the ear drum to the inner ear, and amplify these sounds waves
36
tetrapods: hyoid apparatus (3)
- ventral elements of the hyoid arch + other arches - supports the tongue and larynx - other pharyngeal arches contribute to the cartilages that protect the larynx
37
transcranial joints (2)
- of lepidosauria and aves - mobile joints between dorsal dermatocranium bones - metakinesis, mesokinesis, prokinesis
38
transcranial joint: metakinesis
- near the posterior of the skull
39
transcranial joint: mesokinesis
- just posterior to the eyes
40
transcranial joint: prokinesis
- anterior to the eyes
41
lizards: how do transcranial joints assist with feeding (2)
- mesokinetic mobile joints within the skull permit jaws to operate more efficiently in prehension - angle of jaws can be altered so upper and lower jaw contact prey at same time, so prey is gripped tightly and not pushed away, and so the teeth contact it at a useful angle for secure hold
42
snakes: how do transcranial joints assist with feeding (3)
- skull extensively modified with secondary loss of bone ad mobile joints - right and left side of lower jaw joined by flexible connective tissue, allowing each side to flare outward and move independently - swallow their large prey whole
43
birds: how do transcranial joints assist with feeding (2)
- prokinetic joints within skull allow precise control of angle of the jaws
44
akinetic skull: advantages
- more powerful bite and can withstand force of chewing
45
how is the mammalian skull specialized for feeding (3)
- jaws and teeth used for mastication - much greater and more prolonged forces than prehension - fusion of skull bones: increase in strength to withstand mastication forces, but loss of cranial kinesis
46
how is the mammalian skull specialized for feeding: teeth (2)
- heterodont teeth specialized for cutting/chewing (molars: grinding; carnassials: slicing) - cranial kinesis allows for perfect and reliable alignment of upper and lower jaws for mastication: function best when jaw align perfectly
47
how is the crocodilia skull specialized for feeding (2)
- akinetic skull allows crocodilians to caputure and kill prey with one powerful bite because it can withstand forces - practice prehension
48
primary palate (3)
- separates brain from oral/nasal passage - present in all vertebrates - chondrocranium
49
secondary palate (5) - function - composition (2) - origins - found in:
- separates oral passage from nasal passage so that vertebrate can continue breathing while feeding - can be partial or complete - can be formed of bone, soft and fleshy tissue, or both - when bony: formed by fusion of dermatocranium bones to form a strong, inflexible shelf - found in: testudinata, mammals, and archosaurs
50
which taxon lack a secondary palate
- fish, amphibians, lepidosauria
51
secondary palate: testudinata
- partial, bony secondary palate
52
secondary palate: mammals (2)
- complete secondary palate | - bony anterior and fleshy posterior
53
secondary palate: archosaurs
- complete, fleshy
54
secondary palate: crocodilians
- complete, bony
55
diapsid skull (2)
- 2 pairs of temporal fenestrae | - lepidosauria and archosauria
56
synapsid skulls (2)
- mammals | - 1 pair of temporal fenestrae
57
hypothesis for function of temporal fenestrae (3)
1. provide space for large jaw adductor muscle to increase in diameter during contract (muscles decrease in length, but increase in diameter) 2. rims of fenestrae offer more secure muscle attachment site than smooth bone of skull surface; muscle tendons fuse with bone and distribute forces over a greater area 3. spaces reduce overall volume of bone in skull, decreasing its weight (eg. birds for flight)
58
what are the possible functions of temporal fenestrae in the spotted hyena (mammalian) (3)
- provide space for increased muscle diameter during muscle contraction - rim of fenestrae provide secure muscle attachment sites - this allows large, strong jaw adductor muscles to generate a powerful bite
59
anapsid skull (3)
- testudinata - secondarily lost temporal fenestrae - otic notches to provide powerful bite instead
60
anapsid skull: otic notches (2)
- produce space for jaw adductor muscles to expand in diameter - rims of notches provide secure attachment sites for jaw adductor muscles
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