Transcript Diversity In Dentition

Diversity In Dentition
By Saskia
Herbivore – Cow.
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Cows belong to a family of animals known
as ruminants. Ruminants are animals with
cloven hooves that chew their cud. Other
examples of ruminants are sheep, deer,
goats, giraffes and antelopes.
Cows have 32 teeth (24 molars, 6 incisors
and 2 canines), but instead of top front
teeth, they have a dental pad. A dental pad
is soft cartilage used for chewing cud as well
as helping a cow chew it’s food. There is
also a large gap between the incisors (at the
front of the mouth on the bottom) and the
molars (at the back of the mouth at the top
and bottom). This is called a diastema.
A cow’s teeth are primarily used for grinding
food, and they also have small incisor teeth
on their bottom jaw.
Herbivorous animals, such as cows, have
well-developed pterygoid and masseter
muscles. Pterygoid muscles help open and
close the jaw and move it from side to side.
Masseter muscles work with the pterygoid
muscles to close the jaw. They are also
assist in side to side/front to back chewing.
A cow’s tongue is very long, which helps by
grasping grass when a cow needs to feed.
Herbivore – Cow.
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A cow’s teeth are primarily used for grinding
tough plant materials. To feed, a cow grasps a
clump of grass with its long tongue, and
pinches it together using its small front teeth
and its dental pad. The cow is able to collect a
large amount of grass because of the
diastema (gap between the front incisors and
the back molars). The cow moves the grass to
the back of the mouth, where it can then chew
it properly.
Cows can only eat long grass as their tongue
cannot fully wrap round short grass.
The insides of a cow’s cheeks are rough,
which helps keep food in their mouth while
they chew.
A cow’s jaw muscles (the well-developed
masseter and pterygoid muscles as well as
the temporalis muscle) assist it in chewing
high-fibre plant material. Pterygoid muscles
help to open and close the cow’s mouth, and
the masseter muscles help move the jaw from
side to side. When a cow “chews the cud” you
can see this happening.
The temporalis muscle, which is present in
omnivores and carnivores as well, is less
developed, and as a result, the cow cannot
open it’s mouth wide enough to catch moving
prey.
Omnivore – Human.
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Humans are omnivores because we are
anatomically designed to be able to eat both
plants and animals.
We have 8 spade-like incisors, 4 flattened
canines, 12 molars and 8 premolars. In total
we have 32 teeth by adulthood.
Human teeth are similar to those found in
herbivores, apart from the eye teeth
(canines). Our canines are smaller and less
pronounced than those of a carnivore, and
function largely as incisors.
The facial muscles in humans used for
chewing are the masseter muscle, the
pterygoid muscle, and the temporalis
muscle. Masseter and pterygoid muscles
allow the jaw to perform a wide variety of
movements, and the temporalis muscle
allows for the jaw to be opened extremely
wide.
The masseter and the pterygoid muscles in
humans are well-developed, whereas the
temporalis muscle is not as well-developed.
Omnivore – Human.
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Human incisors are used for biting, gnawing and
snipping at relatively soft materials. At the back of
our mouths, the molars grind and crush the already
pulped food. Omnivores and herbivores carefully
and methodically chew their food, because unlike
carnivores, they cannot swallow food whole.
The canines that we have behave much the same
as incisors, because we don’t need to hunt or catch
our own prey, like a dog. If we were in the situation
where we did have to hunt for our own food, we
would use other means of catching it, such as our
hands, a weapon, or a trap.
Because our diet consists of less harsh plant food
than most herbivores, we have top and bottom
incisors (no dental pad).
The pterygoid and the masseter muscles are welldeveloped in humans, because we eat a wide
variety of different foods, and we therefore need to
perform lots of different jaw movements.
The temporalis muscle in humans is small and of
minor importance, because we don’t need to grasp
hold of our prey with our mouths
Carnivore – Dog.
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Dogs have 42 teeth. These consist of 4
prominent, dagger-like canine teeth, 12
pointed incisors that are predominantly used
for shredding meat from bone, and 26
carnassials (molars and premolars) that are
triangular with serrated edges.
Dogs have a wide mouth in relation to the
size of their heads. Their pterygoid and
masseter muscles are smaller than they are
in herbivores and omnivores. The temporalis
muscle is the most well-developed muscle in
the dog’s head, and this enables it to bite
down quickly onto it’s prey.
Carnivore – Dog.
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The teeth of a dog are large and pointed. This
makes the dog highly equipped for grasping and
killing it’s own prey. The long, sharp canine teeth
enable the dog to bite down and puncture flesh,
while the row of other teeth keep a steady hold of
the prey.
The incisors and molars of herbivores and
omnivores assist with chewing, but a carnivorous
animal’s teeth assist in tearing flesh from bone.
Because a carnivorous animals cannot chew, it just
shears large lumps of meat from it’s prey and
swallows it whole.
A dog’s jaw is relatively large compared to the size
of it’s head. This is because the temporalis muscle
is the most well-developed muscle. The masseter
and pterygoid muscles are relatively unimportant. If
they were larger, the dog would have a smaller
mouth, and subsequently be unable to eat large
portions of meat as it does now.
The masseter and pterygoid muscles assist in
chewing. In dogs, they are relatively undeveloped,
which means a dog has restricted jaw movements,
but this doesn’t hinder the dog in any way, as it
simply eats it’s food whole.
Bibliography.
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http://upload.wikimedia.org/wikibooks/en/b/b1/Anatomy_and_physiology_of_animals_
Sheeps_skull.jpg
http://www.vivo.colostate.edu/hbooks/pathphys/digestion/pregastric/cowpage.html
http://www.face-and-emotion.com/dataface/anatomy/jawinternalmuscles.jsp
http://www.face-and-emotion.com/dataface/anatomy/lowerfacemusclesdetails.jsp
http://vetmedicine.about.com/gi/dynamic/offsite.htm?zi=1/XJ/Ya&sdn=vetmedicine&c
dn=homegarden&tm=137&gps=150_102_1676_904&f=00&su=p284.8.150.ip_&tt=14
&bt=1&bts=1&zu=http%3A//www.vetmed.wsu.edu/ClientED/anatomy/index.asp%23D
og%2520Anatomy
http://www.parks.sa.gov.au/naracoorte/wonambi/reconstructing/muscles/005774