Diversity In Dentition

1. Diversity In Dentition By Saskia

2. Herbivore – Cow. • 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.

3. Herbivore – Cow. • 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.

4. Omnivore – Human. • 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.

5. Omnivore – Human. • 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 well-developed 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

6. Carnivore – Dog. • 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.

7. Carnivore – Dog. • 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.

8. Bibliography. • 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&cdn=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%23Dog%2520Anatomy • http://www.parks.sa.gov.au/naracoorte/wonambi/reconstructing/muscles/005774