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Skulls and teeth

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The shape of an animal’s skull and the arrangement and structure of its teeth have evolved over millions of years to suit what it eats.

Cats and other meat eaters (carnivores) have teeth designed to kill prey and tear flesh. They usually have large pointed canine teeth that stab into their prey. Their molar teeth (carnassial) are sharp and act like scissors cutting and slicing through flesh and bone.

Herbivores such as horses, sheep and elephants have ridged cheek teeth (molars) for grinding plant material. Many have jaws that can move sideways. The canine teeth are often missing or very small. Incisors may be present in the upper and lower jaws for snipping vegetation or only present in the lower jaw where they press against a hard, horny upper palate.

Omnivores like pigs and humans have teeth adapted for a mixed diet of meat and plants. The molars are flat for chewing and grinding while the canines and incisors for cutting and biting.

Elephant skull

Elephant skull

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Horse skull

Horse Skull

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Hippopatmus lower jaw

Hippopotamus skull

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Cat skulls

Cat skulls

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Tasmanian devil skull

Tasmanian devil skull

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Pig skull

Pig skull

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Shark jaws

Shark jaws

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Elephant

Image: Indian elephant skull on display in Discover Nature © National Museums Northern Ireland
Indian elephant skull on display in Discover Nature © National Museums Northern Ireland

An elephant has four large cheek teeth (molars) one each side in the upper and lower jaw. These huge flat topped teeth have ridges and groves to grind plant material.

Image: Indian elephant tooth © National Museums Northern Ireland
Indian elephant tooth © National Museums Northern Ireland

Unlike most mammals an elephant replaces its teeth up to six times during its life. The new teeth grow at the back of the mouth. They move forward slowly pushing the old worn teeth out. When the last set of teeth have fallen out the elephant can no longer feed and will die.

Tusks are modified incisor (front) teeth in the upper jaw. They are used for digging, moving and debarking trees and for defence.

Image: Elephant tusk on display in Discover Nature © National Museums Northern Ireland
Elephant tusk on display in Discover Nature © National Museums Northern Ireland

When the tusks start to grow they have an enamel coating that wears off exposing the dentine or ivory. Thousands of elephants are illegally killed every year for their ivory tusks.

Horse, Giraffe and Sheep

Horse skull and sheep skull © National Museums Northern Ireland
Horse skull and sheep skull © National Museums Northern Ireland
Horse skull (on left) and giraffe skull © National Museums Northern Ireland
Horse skull (on left) and giraffe skull © National Museums Northern Ireland

Horses, giraffes and sheep are herbivores - they eat plants. Plant material is tough and hard to digest. Herbivores have broad, ridged molars (cheek teeth) to grind their food to a pulp before they swallow it. Sheep have lower jaws that can move sideways allowing them to grind their food more efficiently.

Horses have incisor (front) teeth in both the top and bottom jaw to grip and pull off mouthfuls of grass.

Image: Giraffe skull showing teeth © National Museums Northern Ireland
Giraffe skull showing teeth © National Museums Northern Ireland

Sheep and giraffes do not have any incisor teeth in the top jaw – instead they have a tough horny pad. They use their tongue and lips to pull food into their mouth. The sharp incisors in the lower jaw push against the horny pad to cut through the food.

Hippopotamus

Image: Hippopotamus lower jaw on display in Discover Nature © National Museums Northern Ireland
Hippopotamus lower jaw on display in Discover Nature © National Museums Northern Ireland

Hippos spend much of their time in water to stay cool.

In the evening when the sun goes down they come out of the water to feed on grass. They use their horny lips to pull grass into their mouth which is then ground to a pulp using their molar teeth.

The hippopotamus has an enormous mouth that can be up to 1.2m across and huge ivory canine tusks, the largest of any land mammal. The tusks in the upper and lower jaw grind against each other to stay sharp, the incisors are also very large.

Hippos are very aggressive animals and use their teeth in fights.

Tiger, leopard and domestic cat

Image: Tiger skull, leopard skull and cat skull © National Museums Northern Ireland
Tiger skull, leopard skull and cat skull © National Museums Northern Ireland

Cats are carnivores and their teeth have evolved to eat a meat diet.

The canines are long and pointed to penetrate the prey’s body. The killing bite usually severs the spinal cord. The molars or carnassial teeth are very sharp and work like scissor blades sliding past each other to cut off pieces of meat and bone.

Tiger skull showing the sagittal crest on top of the skull © National Museums Northern Ireland
Tiger skull showing the sagittal crest on top of the skull © National Museums Northern Ireland
Tiger skull showing teeth © National Museums Northern Ireland
Tiger skull showing teeth © National Museums Northern Ireland

A big cat like the tiger has strong muscles that attach the lower jaw to the skull. A large bony ridge (sagittal crest) has evolved on top of the skull to give a secure attachment point for these muscles. This gives the tiger a very powerful bite.

Tasmanian Devil and Hyena

Tasmanian Devil skull © National Museums Northern Ireland
Tasmanian Devil skull © National Museums Northern Ireland
Hyena skull © National Museums Northern Ireland
Hyena skull © National Museums Northern Ireland

The Tasmanian Devil is the largest living carnivorous marsupial (pouched mammal). It is a noisy animal about the size of a small bulldog with a large head and powerful bite. A devil can kill prey up to the size of a small kangaroo but usually feeds on dead animals (carrion).

The Tasmanian Devil and the hyena have teeth that can through and crush bone - nothing is left behind at the end of a meal.

Thousands of Tasmanian Devils have been killed by an unusual cancer. Infected devils spread the cancer when they bite each other.

Domestic pig, wild boar and warthog

Image: Domestic pig skull © National Museums Northern Ireland
Domestic pig skull © National Museums Northern Ireland

The domestic pig is a subspecies of the Eurasian wild boar. It was one of the first animals to be domesticated by humans.

Pigs are omnivores and will eat almost anything including roots, bulbs, fruit, nuts, fungi, snails, earthworms, small animals, eggs and carrion (dead animals).

They have 44 permanent teeth that have evolved to handle their varied diet. The rear teeth (molars) are used to crush food.

Wild boar skull © National Museums Northern Ireland
Wild boar skull © National Museums Northern Ireland
Warthog showing large curved tusks © National Museums Northern Ireland
Warthog showing large curved tusks © National Museums Northern Ireland

The canine teeth grow continuously. In male animals they can grow very long and are called tusks. Tusks can be seen outside the mouth.

Shark

Image: Shark jaws © National Museums Northern Ireland
Shark jaws © National Museums Northern Ireland

A shark skeleton is not made of bone. It is made of same material as the human ear - cartilage. Cartilage is strong and flexible, it is also very light helping the shark to stay afloat.

Shark skin is very tough and covered in minute enamel coated teeth called dermal denticles. The denticles point backwards and help to reduce drag allowing the shark to swim faster.

Shark teeth are larger versions of skin denticles. They are made of enamel and face inward. The jaw is like a rolling conveyor belt, with multiple rows of teeth that are continually replaced every two – three weeks.

Some sharks have smooth pointed teeth whilst others have teeth with serrated edges. They do not chew their food – they just bite off chunks and swallow them.

Close up of the multiple rows of serrated teeth in the jaw © National Museums Northern Ireland
Close up of the multiple rows of serrated teeth in the jaw © National Museums Northern Ireland
Close up of the multiple rows of smooth pointed teeth in the jaw © National Museums Northern Ireland
Close up of the multiple rows of smooth pointed teeth in the jaw © National Museums Northern Ireland