Lab 4 - skull Flashcards
chondocranium
encases special sense organis, contrib to skeletal elements encasing brain, back (posterior), sides (lateral regions), and floor of the brain case
from mesenchyme and neural crest cells
endochondral bone or cartilage
dermatocranium
dermal bones encasing the chondocranium
from mesodermal mesenchyme and neural crest cells
splanchnocranium
from mesodermal mesenchyme and neural crest cells
pharyngeal arches that support the pharynx and gills
evolved into middle ear bones, hyoid apparatus, jaws in some gnathostomata
most verts - 7 pharyngeal arches
FIRST ARCH - jaws, palatoquadrate and meckel’s cartilage
jaw suspension
att differently in different taxa
types of jaw suspension
paleostyly, autostyly, hyostyly, modified hyostyle, metautostyly, craniostyly
10 bones of the general teleost dermatocranium
- maxilla
- premaxilla
- nasal
- jugal
- squamosal
- lacrimal
- frontal
- parietal
- interparietal
- dentary (of the lower jaw)
*** called mandible when fused together at mandibular symphysis
3 components of dermatocranium
- occipitals
- sphenoids
- ethmoids (thin curled bones in olfactory chamber/nasal passage)
*** in the anterior of the brain cas
** in many mammals, olfactory chamber divided in 2 by MESETHMOID BONE
????? ID occipitals vs sphenoids vs ethmoids of the chondocranium
capsules formed by the chondocranium
- olfactory capsule
- optic capsule
- otic capsule
+inner/mid ears
maxilla location
front dorsal region of the snout
premaxilla location
most anterior point of the snout/ anterior to maxilla
nasal bone location
top midline of the snout
lacrimal bone location
very front (anterior, dorsal) of the eye sockets (little bone)
jugal bone location
small process on the anterior/lateral/dorsal region of the optic capsules
squamosal bone location
the posterior region of the optic capsule
frontal bone location
dorsal region of the braincase between the two optic capsules
parietal bone location
dorsal, posterior region of the braincase posterior to the optic capsules
interparietal bone location
most posterior region of the braincase, just behind the parietal bone
dentary location
lower jaw!!!!
1st pharyngeal arch
MANDIBULAR ARCH - contributes to the jaws in several gnathostomes
in mammals - quadrate forms the incus and palatoquadrate forms the malleus of the middle ear
2nd pharyngeal arch
HYOID ARCH
suspends the jaw in some gnathostomes, in some contributes to the hyoid apparatus
forms COLUMELLA in sauropsids
forms STAPES of middle ear in mammals
paleostyly - what?
no jaw!
paleostyly - who?
agnathans - myxinoidea and petromyzontida
autostyly - what?
Upper jaw - palatoquadrate
lower - meckel’s cartilage
Hyoid arch - no support, palatoquadrate attaches directly to chondrocranium
autostyly - who?
holocephali (dogfish)
hyostyly - what?
upper jaw - palatoquadrate
lower jaw - meckel’s cartilage
hyoid arch - hyomandibula, swinging bridge attaching the palatoquadrate to the chondocranium
hyostyly - who?
elasmobranchii
modified hyostyly - what?
upper - maxilla and premaxilla (dermal bone from dermatocranium + quadrate from the palatoquadrate/mandibular arch
lower - angular and dentary bones (dermal) + articular bone from meckel’s cartilage
*** quadrate and articular articulate w/each other
hyoid arch - HYOMANDIBULA + other dermal bones swinging bridge attaching the quadrate to the chondocranium
metautostyly - what?
Upper jaw - maxilla and premaxilla (dermal) + quadrate from palatoquadrate
Lower jaw - dentary + other dermal bone + articular from meckel’s cartilate
***quadrate articulates with articular
Hyomandibula - modified to columella of middle ear
quadrate directly attached to the chondocranium either a) immobile
b) mobile - STREPTOSTYLY
modified hyostyly - who?
actinopterygiians
metautostyly - who?
amphibians and sauropsids
craniostyly - what?
upper - maxilla and premaxilla
lower - dentary
**ARTICULATES W/ SQUAMOSAL bone of braincase
upper is completely fused to brain case!!
quadrate = incus of the middle ear
articular = malleus of the middle ear
hyomandibula = stapes of middle ear (homologous to the columella of amphibians and sauropsids)
tympanic bulla
encase the inner and middle ear in mammals
palattes in fish and amphibians
ONLY PRIMARY
palates in sauropsids
ALL - primary
Crocodilia - complete 2nd, bony
Aves - complete 2nd, fleshy
Lepidosauria - USUALLY only primary
Testudinata - Partial 2nd, bony
Mammalia - Complete 2nd, bony anterior, fleshy posterior
what do incus malleus and stapes look like?
stapes - stirrup
malleus - mallet (w/ stick and ball)
incus - not a stirrup or mallet
for what species does the dermatocranium cover the dorsal surface of the brain?
amia (actinopterygii)
classification based on temporal fenestrae
Testudinata - ANAPSID = none
Mammalia - SYNAPSID = only infratemporal
Lepidosauria, Aves, Crocodilia - DIAPSID = infratemporal and supratemporal
sagittal crest
longitudinal crest along the midline of mammalian skulls, along paired parietal and frontal bones
nuchal crest
crest running perpendicular to sagittal crest in mammalian skulls, across the occipital bones
homodont
all teeth very similar shape
heterodont
teeth different shapes
4 main heterodont tooth types
canines, incisors, molars, premolars
specialized tooth for carnivores
CARNASSIALS - 4th premolar of upper and first molar of lower
diastema
large gap vetween incisors and molars in herbivores
