skulls Flashcards
fenestrae or fenestrations
openings that are a result of the presence of one or more arches
purpose of fenestrations
allow muscles of lower jaw to attach to the surface of bones that surround the rim of the openings
anapsid
“without arch” – do not possess temporal arches
in extant amniotes, only turtles have anapsid skulls
temporal muscles run from neurocranium to lower jaw
emarginations
shallow notch similar to fenestrae present in turtles but are not homologous structures
synapsid
“together arch” – skulls possess a single arch on each side of the skull
extensive attachment of jaw muscles to the surface of the dermatocranium
infratemporal arch
composed of jugal, quadratojugal, squamosal bones… in extant mammals, the quadratojugal is often lost and the arch is frequently referred to as the zygomatic arch
diapsid
“two arches” – skulls possess two arches on each side of the skull
basic skull condition for reptiles
extensive attachment of jaw muscles to the surface of the dermatocranium
superior temporal fenestra
uppermost arch, the supratemporal arch and the opening defined by this arch
consists of the postorbital and squamosal bones
infratemporal fenestra
lowermost arch, infratemporal arch and the opening defined by this arch
consists of the jugal, quadratojugal, and squamosal bones
modifications of diapsid skulls
crocodylians and tuataras possess unmodified diapsid skull
birds have lost supratemporal arch
lizards have lost infratemporal arch (loss of quadratojugal)
snakes have lost both arches (loss of squamosal and quadratojugal)
heterodont
animals which possess more than a single tooth morphology
mammals
homodont
having teeth that are all the same type
most nonmammalian vertebrates
diastema
space or gap between two teeth; area denuded of teeth
carnassial teeth
laterally compressed, for shearing
molariform teeth
molars and premolars
dental formula
I C PM M / I C PM M = one side of mouth (upper/lower) as there can be variation in top and bottom but not sides
mandible
two dentary bones fused at their anterior ends, mandibular symphysis
styloid process
attachment site of a tongue muscle called the styloglossus muscle
sella turcica
=Turkish saddle
bony concavity that houses the pituitary gland
cribiform plate
region where olfactory neurons from the nasal region enter the brain
crista galli
vertical plate projecting up from the cribiform plate; serves as the attachment site for the meninges that enclose the brain
fontanel
“soft spot” in the head of a newborn that has not yet ossified
modifications of synapsid skulls
most modern mammal synapsid skulls are slightly modified - the quadratojugal and postorbital bones are lost
temporal bone
represents fusion of three bones: prootic, opisthotic, squamosal
