GLOSSARY of Skullological Terminology

Alveolus

The socket into which the root of a tooth fits.

Angle

The lower back corner of the lower jaw.

Anterior

Towards the front.

Ascending Ramus of Jaw

The more or less vertical part of the jawbone which carries the joint with the skull.

Brachycephalic

Short-headed. Referring to breeds of dog such as boxers, with forshortened snouts.

Braincase

Part of the skull containing the brain.

Bulla

Bulbous part of the ear bones.

Bunodont

Low-crowned, rectangular grinding teeth, typical of the molars of omnivores such as bears and primates.

Canines

The four teeth in the front corners of the mouth. Usually large and pointed in carnivores, but may be small or absent in herbivores. They are the first teeth in the maxilla, called eye-teeth in humans.

Carnassials

Scissor-like teeth of carnivores specialised for shearing flesh. The last upper premolars and first lower molars.

Carnivore dentition

Tooth pattern found in most meat-eaters, featuring prominent canine teeth with shearing carnassial cheek teeth.

Cheek teeth

The teeth behind the canines, usually divided into molars and premolars.

Choanae

Where the rear edge of the palate has a central projection (e.g. in dogs), the choanae are the indentations on each side.

Colonic Literature

Academic papers incorporating in their titles a superfluous subtitle separated by a colon.

Condylar process

Smoothly rounded projection from the rear of the dentary where the lower jaw articulates with the skull.

Condyle

Smooth rounded projection of bone which forms a bearing or articulating surface in a moveable joint.

Condylobasal length

Coronoid process

The back part of the lower jaw which rises up.

Cranium

The skull without the lower jaw.

Dentary

Bone forming one side of the lower jaw.

Dentition

The full set of teeth. Most mammals have specialised carnivore, herbivore or insectivore dentition. Dental formulas are given for most of the skulls illustrated.

Diastema

A long natural gap in a row of teeth, especially that between the incisors (or canines) and the cheek teeth in herbivores.

Dolichocephalic

Long headed. Referring to breeds of dog such as collies and greyhounds.

Dorsal

Concerning the top: e.g. "dorsal view" is a view from the top.

Epiphysis

The smooth, rounded or curved area at the end of a bone, forming an articulating surface of a joint. In young animals epiphyses are separated from the main body of the bone by a layer of cartilage, to allow for growth. The timing of their fusion gives a clue as to the age of the individual.

Eurokaryotic

Conforming to EU legislation on chromosome number.

Foramen

Hole in a bone for nerves and blood vessels.

Foramen magnum

Large opening in the back of the skull, through which the spinal cord leaves the brain. The occipital condyles lie on either side.

Frontal bones

Form the top, front part of the braincase.

Herbivore dentition

Tooth pattern found in typical plant-eaters such as cattle and rabbits. Prominent incisors are separated from the cheek teeth by a long diastema.

Horn core

Porous bone projecting from the frontal bone, on which the horn grows.

Incisiform

Shaped like an incisor. In some herbivores, especially deer, the lower canine teeth form part of the row of incisors instead of being cylindrical and pointed.

Incisors

Front teeth, between the canines. Upper incisors grow from the premaxilla, but other upper teeth grow from the maxilla.

Infraorbital foramen

A large hole in the side of the maxilla, usually in front of or below the orbit.

Insectivore dentition

Teeth mostly simple points, as in the hedgehog, mole and shrews.

Interorbital width

Interparietal bone

Lies between the parietal bones and the occipital bone. Useful in separating rabbits and hares.

Jaw length

Lacrimal bone

Forms the front edge of the orbit. Large and distinct in hoofed mammals, but small in most other species.

Lacrimal pit

A depression in the lacrimal bone.

Lagomorph

The group containing rabbits, hares and pikas.

Lateral

Concerning the side. e.g. "lateral view" is a view from the side.

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Lophodont

A tooth with the cusps elongated to form narrow ridges.

Maxilla

Bone forming the main part of the upper jaw on each side, supporting the canines and cheek teeth.

Molars

The rear cheek teeth which do not have equivalent milk teeth.

Mustelid

Sub-group of the Carnivores, including stoats, polecats, badgers and otters.

Nasal bones

Forming the upper surface of the muzzle.

Nasal length

Occipital bone

Forming the back of the skull. Contains the foramen magnum.

Occipital condyles

Smooth, rounded knobs on each side of the foramen magnum, where the skull articulates with the first vertebra. Mammals have two occipital condyles, birds and reptiles have only one.

Occipital crest

A ridge formed where the parietal bones join the occipital bone, across the top, back part of the skull.

Orbit

The eye socket.

Orbital diameter

Orthodont

Normal rodent upper incisors, pointing downwards. (see pro-odont)

Palate

The surface forming the roof of the mouth.

Parietal bones

Form the top, back part of the skull.

Posterior

Towards the rear.

Postorbital process

Projection from the frontal bone that marks the rear, upper edge of the eye socket.

Postorbital constriction

Premaxillas

Bones forming the front tip of the upper jaw.

Premolars

Cheek teeth lying between the canines (or incisors, if canines are absent) and the molars.

Pro-odont

Rodent incisors which point forwards. (see orthodont)

Ramus

The main horizontal part of the lower jaw.

Root

The part of a tooth embedded in the jaw. Teeth may have from 1 to 5 roots.

Rootless

Continuously growing tooth which is the same in cross-section all the way down to the basewhere it is embedded in the jaw. The base of the tooth does not divide into roots.

Rostrum

Bones of the muzzle.

Sagittal crest

Ridge running lengthwise along the top of the braincase.

Selenodont

Teeth with a crown pattern of longitudinal crescentic ridges.

Suture

Immovable joint between bones.

Temporal Ridge

Ridge on the side of the cranium marking the upper limit of the temporalis muscle. In some species they develope with age, and may also migrate towards the top of the skull to form an interparietalridge (e.g. badger).

Unicuspid

Teeth with a single cusp or point, e.g. the simple conical teeth of insectivores.

Ventral

Concerning the underneath: e.g. a ventral view is a view from the bottom.

Zygomatic Arch

The cheekbone. Curved bone forming an arch along the side of the skull below the orbit.

Zygomatic width

SKULL MEASUREMENTS
Measurement	Abbreviation	Description
Condylobasal length	CB	The length of the skull, measured from the front of the premaxilliary bones to the rear surface of the occipital condyles.
Interorbital width	IW	Minimum distance between the upper edges of the orbits, measured across the top of the skull.
Jaw length	JL	The length of the lower jaw, from the front tip of the dentary bone to the angle.
Maximum palate width	PW	The maximum width across the alveoli of the cheek teeth.
Minimum palate width	MW	The minimum width across the palate, measured behind the canines.
Nasal length	NL	Overall length of the nasal bones.
Orbital diameter	OD	Maximum diameter of orbit, from rim to rim. May be specified as (horizontal) length or (vertical) height.
Overall length	OL	Maximum dimension of the skull when laid on level surface.
Palate length	PL	From the front of the alveolus of a first incisor, to one of the choanae on the same side at the rear of the palate.
Postorbital constriction	PC	Diameter of the narrowest part of the braincase immediately behind the orbits.
Zygomatic width	ZW	The maximum width across the zygomatic arches (cheekbones).

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