Flashcards in Skulls-Modifications Deck (20):
Describe 2° palate of birds & why
-lighter -> lighter head -> better for flight
Define cranial kinesis
Articulation points in skull other than between upper & lower jaw
Who has a primary palate, and what is its function?
All vertebrates; separates brain from mouth (protects ventral brain)
What do mammals typically use their jaws and teeth for?
Mastication: chewing, grinding, slicing food
Describe 2° palate of mammals & why
complete - anterior: hard, posterior: soft
-Good to breathe while chewing (takes a long time)
-Allows infants to breathe while creating suction for nursing
Who has an akinetic skull?
Mammals, turtles, crocodilians, most amphibians
What compromise do snakes have to make because of their kinetic skull?
Skull is weak, so can't eat living prey -> must paralyze with venom or kill by constriction first
Who has a 2° palate?
Mammals (complete, hard & soft)
Some turtles (partial, bony)
Crocodilians (complete, hard)
Aves (complete, soft)
Describe cranial akinesis in mammals
Bones are fused to withstand forces of mastication without jostling brain; aligns teeth (e.g. carnassials, molars) perfectly for slicing or grinding
-Lose kinesis, limiting food size
Who has a kinetic skull?
Many squamates, aves
functions of temporal fenestrae
-provide space for jaw muscles to expand during contraction
-more secure muscle attachment site
-less bone in skull is lighter
Function of 2° palate
Separate nasal passage from mouth (respiration vs. food)
Describe 2° palate of crocodilians & why
Complete: Allows breathing through nose while head is underwater
Bony: Withstand forces of wresting prey underwater
(Causes skull to be more akinetic)
Describe cranial kinesis in lizards
Provides more efficient prehension by having upper & lower jaw contact prey simultaneously, and redirecting forces into prey, not outwards/forwards
Which bones form the bony palate?
Maxilla, premaxilla, palatine (dermatocranium)
What do snakes do, since they have no 2° palate?
Stick out their trachea while they swallow their food
Who doesn't have a 2° palate?
Fish, amphibians, most lepidosaurs
How are temporal fenestrae a compromise?
Decrease brain protection (but also have chondrocranium beneath) to increase bite strength
What do amphibians and sauropsids use their jaws & teeth for?
Prehension: grabbing, holding food