Skull Studies

Skeleton

• Framework of an animal’s body• Gives shape, support, and protection• Vertebrates, endoskeleton• Muscle attachment allowing for movement• Skull portion includes teeth and bone plates

• Skeleton is a result of evolutionary change– Animal adaptation to their environment– Role or niche

• Analyzing an animal’s skeletal structures of vertebrates– Infer its eating habits– Environmental lifestyle

The Skull

• Mammal skulls are made up of two series of bones– Paired bones– Unpaired bones

Paired Bones of the Skull

• Back of the skull– Parietals, towards the back of the skull– Frontals, front of the skull– Maxillas, under the eyes– Premaxillas, under the nose (not present in humans)– Nasal

Underneath the Skull

• Palatines, roof of mouth

On the Sides of the Skull

• Zygomatic, cheekbones (squamosal flat, and jugal point)

• Orbit, protecting the eyes (temporal fossa, opening behind the orbit)

On the Top of the Skull

• Sagittal Crest, midline toward the rear of the head, develops on the parietals. Temporal muscle attachment.

Unpaired Bones of the Skull• Back to Front– Occipital– Bassioccipital, between the auditory bulla– Preshenoid, indention b/w bassiocciptal & palatine– Vomer (inner nasal bone, laying on maxilla)– Occipital condyles, points of movement between

the skull and the backbone – Foramen magnum, passes the spinal cord

From the Bottom

• Auditory bullae, houses the inner ear

Rostrum• Inside the nasal area there are visible scroll –

like convolutions of nasal turbinates– Support the moist membranes of the nose

Lower Jaw

• Mandibles join in the front• Back of each side is the mandibular condyle,

joined to the skull• Coronoid process, tall wing-like area of the

jaw where some of the muscles that close the jaw attach

The Teeth• Four types of teeth– Incisors, 3 lie in the premaxilla• Used for nipping and pulling of food

– Canines, long and curved sharp conical tooth• Used for piercing

– Premolars, sharp and have one main point or cusp• Used to grasp and tear

– Molars, triangular teeth with strong blunt cusp• Used for crushing, lower jaw may have fewer molars• Carnassial shearing tooth is the first molar in the lower

jaw and fourth premolar in the upper jaw (carnivore)

Dental Formula

• Used to identify species• Short hand used to write the dental formula– ICPM– Fraction show upper then lower teeth for one side– Example, Canine I 3/3 , C 1/1, PM ¾, M 3/2

Carnivore

• Sharp serrated edges to tear and cut flesh• Incisors, narrow, smaller teeth, sharp edges• Canines, highly developed, longer for gripping

and tearing• Premolars, twin conical peaks used for cutting• Molars, serrated used for cutting

Herbivore• Flat molars, no canines or premolars• Adaptations in dental structure reflect methods

of obtaining food– Rodents (Muskrat), gnawing long curved incisors

(orange)– Browsing (Deer), incisors present in mandible not in

maxilla, molars flat and well formed– Cropping (Horse), sharp edge incisors both jaws

Omnivore

• Great variety of sizes and shapes, basic structure is the same

• Well developed incisors, canines, molars• Combination of herbivore and carnivore• Humans, bears, pigs

Insectivore

• Conical narrow teeth for piercing exoskeletons• Opossum