Copy of `usgs - Skulls of North Dakota Mammals`

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usgs - Skulls of North Dakota Mammals
Category: Animals and Nature
Date & country: 30/06/2013, US
Words: 50


antler
a branched bony projection of the frontal bone; covered with vascularized tissue (velvet) during growth; shed annually.

auditory (tympanic) bulla
the inflated bony capsule that encases the middle and inner ear.

basal length of skull
the distance from the anterior border of the foramen magnum to the anterior margin of the premaxilla.

basilar length of skull
distance from posterior border of the tooth socket of the median incisor to mid-ventral border of foramen magnum.

basioccipital
bone that forms the ventral margin of the foramen magnum.

basisphenoid
the median ventral bone lying between the auditory bullae anterior to the basioccipital.

breadth of braincase
greatest width of skull in region where the brain is housed.

canine
the most anterior tooth in the maxilla, found just behind the incisors; often long, stout, and cone-shaped.

cheekteeth
premolars and molars.

condylobasal length
distance from anterior border of the tooth socket of the median incisor to plane of posterior border of occipital condyles.

crown
the portion of a tooth extending above the gumline.

cusp
a point on the crown of a tooth.

dentine lake
isolated area of dentine surrounded by enamel.

diastema
a gap separating molariform teeth from anterior ones, usually incisors.

external auditory meatus
bony canal leading into the auditory bulla.

foramen
an opening, orifice, or perforation through bone.

foramen magnum
the opening in the posterior of the skull through which the spinal cord passes.

frontal
a paired dermal bone of the dorsal part of the skull, located between the nasal and parietal bones.

greatest length of skull
greatest distance between most anterior point of skull (excluding teeth) to most posterior point of skull.

horn
permanent structure projecting from the skull of certain mammals, consisting of a bony core covered by keratin sheaths (keratin sheaths are shed annually in pronghorn).

incisive foramina
paired perforations through the anterior end of the hard palate at the point where the premaxilla and maxilla meet (also called palatine slit).

incisor
the most anterior of the four basic kinds of teeth; rooted in the premaxilla.

infraorbital opening (canal)
passage from the anterior face of the orbit to the side of the rostrum, passing through the base of the maxillary process.

interorbital breadth
least measurement across skull between orbits.

interparietal
an unpaired bone in the roof of the skull located between parietals and supraoccipital.

keratin
a protein material of which the covering of horns is composed.

lacrimal
a bone of the skull located in front of the orbit.

lacrimal fossa
a depression in the lacrimal bone anterior to the orbit.

mastoid
a process on the temporal bone posterior to the auditory meatus.

maxilla
bone that forms part of the roof of the mouth in which the upper molars, premolars and canines are rooted (found posterior to premaxilla).

maxillary breadth
the width of the skull across the maxilla.

maxillary tooth row
line of teeth in the maxilla (canines to molars).

molar
a cheektooth situated posterior to the premolars and having no deciduous precursors.

molariform
all teeth posterior to the canines; includes premolars and molars.

nasal
a paired dermal bone medial and posterior to the external nares.

occipital condyles
two knobs on the occipital bone flanking the foramen magnum.

occlusal
pertaining to the surface of contact between the upper and lower teeth.

orbit
the bony socket in which the eye is located.

palate
bony plate formed by the palatine bones and palatal branches of the maxilla and premaxilla; separates the nasal passages from the oral cavity.

parietal
a paired dermal bone of the roof of the skull, located between the frontal and occipital bones.

postorbital process
a projection of the frontal bone which marks the posterior margin of the orbit.

premaxilla
bone in which upper incisors are rooted.

premolars
teeth located anterior to the molars and posterior to the canines.

rostrum
the facial region of the skull lying anterior to a plane drawn through the anterior margin of the orbits.

sagittal crest
dorso-medial longitudinal ridges on the brain case.

tooth row
line of teeth from the incisors through the molars.

unicuspid
a tooth with a single cusp.

zygomatic arch
the arch of bone that forms the lateral border of the orbit and temporal fossa.

zygomatic breadth
the greatest width across the zygomata, measured at right angles to the long axis of the skull.

zygomatic plate
the expanded and flattened lower maxillary process.