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Mammal Skeletons Part 2 By The Nature Collection for British Wildlife

Mammal Skeletons: Part Two

Mammal Skeletons

The skeleton will be examined, in the following order.

Click below, to go directly to a section.

In this presentation, I will focus on different parts of the skeleton. Search on Google for images of the whole skeletons of a fox, badger, rabbit, mouse, hedgehog and squirrel.

Photo shows a Grey squirrel's pelvis and vertebrae. (The whole pelvis is 5cm long.)

Shoulder Blade

The main photo shows a Grey squirrel's shoulder blade.

The mammal shoulder blade, or 'scapula', is a similar shape for most of the mammal species. A flat, triangular bone, with a narrow ridge running along the centre and a cup-shaped socket at the top end. Muscles cover the wide, flat surface area.

The Hedgehog has a solid, sturdy shoulder blade, shown in the main photo.

Hedgehog's shoulder blade
Paper-thin shoulder blades and neck vertebrae from a Field mouse. The shoulder blades are just 1cm long.

The Mole has long, thin shoulder blades, which spread the impact of the Mole's vigorous digging along the length of the rib cage. Their shape is similar to birds' shoulder blades, which are also long and thin.

Mole's unusually-shaped, long, thin shoulder blades, 2.5cm long x 0.5cm

Like the animals themselves, shoulder blades vary enormously in size. The shoulder blade of a deer is about 20cm long whereas a Field vole's shoulder blade is just under 1cm!

A shoulder blade from a Field vole, almost as small as the petal of a Daisy.
Fox's shoulder blade

The shoulder blades connects the front legs, or fore limbs, of an animal to the muscles along the backbone and ribs. The shoulder blades rest over the top of the rib cage.

Long thin shoulder blades, 1.7cm long, from a Robin, resting on the rib cage, which is just 1.6cm deep

The upper arm bone, the 'humerus', attaches to the narrow end of the shoulder bade with a ball and socket joint. There is a ball-shape at the top of the humerus. This type of joint gives the front legs a wide range of movement.

Rat's shoulder blade, 2.5cm long, attached to the ball on top of the humerus.

Fore Leg Bones

Most land mammals, such as foxes, badgers and deer run and walk on four legs but some also use their fore limbs for manipulating food, fighting, killing, swimming or , for bats, even flying!

A swimming Otter

Many mammals also use their front legs for digging, either looking for food or digging tunnels for their underground homes. For example, rabbits, mice, voles, badgers and foxes.

The main bones in the front and back legs, or 'limbs', follow the same pattern of one large bone connected by a hinge joint to two thinner, parallel bones.

The front leg bones are the long 'humerus', with a ball at the top connecting to the shoulder blade; then, two long, narrow bones, the 'radius' and 'ulna', which can twist over each other, like in the human arm.

Field vole's humerus, 1.1cm long x 0.2cm wide
Tiny radius and ulna, 1.3cm long, from a Field vole

The humerus connects to the radius and ulna with a hinge joint. This type of joint only allows the arms / front legs to move in one direction, up and down, but not to twist around as with a ball and socket joint. It is more stable. The joints in the knees, fingers and toes are also hinge joints. These joints allow the legs, fingers and toes to bend and straighten.

Badgers and moles which live in tunnels, have relatively short legs. Hedgehogs have short, sturdy legs; they do not need to flee from their prey, as they have the added protection of their spines.

Hedgehog, humerus 2.8cm long x 0.8cm wide
Hedgehog, radius and ulna, 3.3cm long. These are equivalent to our forearm bones

Squirrels have a lightweight skeleton, with long, thin legs, adapted to a life spent scampering around in the trees.

Grey squirrel, radius and ulna, 5cm long

Moles have a very distinctive humerus. It is not long and thin but broad and thick. Their front claws are huge digging machines and the large digging muscles need somewhere equally large, to attach onto.

Mole, humerus, 1.6cm long x 1.3cm wide

Mammals which run quickly to escape danger or catch their prey, like deer and foxes, have long, thin legs.

Many mammals like deer, foxes and dogs have a third, long bone in their legs. This has evolved from the fused wrist /finger bones. This extra section gives the animal more speed and leverage when they push off and run. It connects with another hinge joint, in the opposite direction.

Red deer calf

In the deer photo above, the elbow joint bends backwards in line with the base of the stomach. The third section to the left front leg, points straight down, almost vertically.

Pelvis

The main photo shows the pelvis from a Rat.

The hip bones, or 'pelvis', transmit the push from the hind legs to the rest of the body. The back legs drive the body forward.

The hind legs connect to the hips with a ball and socket joint. The ball shape projection on top of the thigh bone, or 'femur' fits into the cup-shaped socket in the pelvis. This allows the back legs to rotate, with a wide area of movement.

See the cup-shaped socket in a squirrels' pelvis, 5cm long

The two bones of the pelvis link together, around the 'sacral vertebrae'. In birds, the pelvic bones are fused with the vertebrae in this area, for added stability.

House sparrow. The pelvic bones are fused with the vertebrae to form one bone. The pelvis and tail bones measure 2.5cm in total.

In the Mole, the four sacral vertebrae are fused with the pelvic bones. This gives reduced flexibility but extra stability.

Mole. a long, thin pelvis fused with the vertebrae, 2.5cm long x 0.8cm wide.
Rat, four unfused sacral vertebrae, between the two long, pelvic bones, which are 4cm long.

The pelvis lies horizontally along the spine. Muscles which move the legs and knees, attach onto the surface of the pelvis.

Field vole pelvis, 1.5cm long x 0.5cm wide, attached so that the hind legs join at right angles with the spine.

Animals like the rabbit which run, have a longer, thinner pelvis. This gives them extra leverage when they push off and leap across the ground.

Rabbit pelvis, 7.5cm long x 4cm wide. Also, sacral vertebrae

Slow-moving, heavy animals like the badger have a broader pelvis, with more surface area where the muscles can attach.

Animals which walk on four legs have their hind legs coming out at right angles to the spine. Humans, who walk on two legs, have their legs in a straight line with the spine. This helps put the weight over our feet.

Field vole's pelvis and femur, connecting with a ball and socket joint. Femur is 1.2cm long.
For scale, four tiny Field vole pelvic bones, 1.5cm long, inside a pea pod!

The pelvic bones for male and female mammals are slightly different shapes as for females, the pelvis must be wide enough for their babies to fit through, when they are born.

Hind Leg Bones

The thigh bone, or 'femur' is usually the longest bone in the body. It is one of the strongest as it has to support the weight of the animal. Fast moving animals like mice and voles, have a relatively thin femur. Slow-moving animals like the hedgehog and mole, have a wider femur.

Tiny thigh bones from a Field vole, 1.2cm long, inside a mushroom, for scale. The bones were found in Barn owl pellets!

Below the femur, are the two narrower bones, the 'tibia' and 'fibula'. The tibia is the weight-bearing shin bone. The fibula is thinner and does not support the body. It anchors the muscles for the ankle and foot.

Rat, femur 3.4cm long, and top of the tibia and fibula
Field vole, two x tibia and fibula, 1.7cm long x 0.3cm wide

In some small mammals, like the vole, the fibula is fused with the tibia to form a bone which resembles the clasp of a brooch.

Grey squirrel, long, thin tibia and fibula, 6.4cm long
.Hedgehog, fused tibia and fibula, 2.5cm long. Sturdy bones for carrying the weight

Where the femur joins the fibula and tibia, is the knee joint. This is a 'hinge joint', which allows the bones to move only in one direction.

Field mouse, knee joint.

In fast-moving prey animals like horses and deer, the lower legs bones are largely fused to form one bone. This reduces flexibility but improves stability. As in the fore limbs, the legs have an extra section which is the fused foot bones. This gives extra leverage and, significantly extends the animal's stride.

Red deer calves. Note the three long sections in the legs.

Animals which move by jumping, such as the rabbit, have longer hind legs than fore legs. They have much bigger muscles in their back legs.

Feet and Claws

There are three different ways in which mammals can move over land.

  • Walk with the whole foot touching the ground, like humans, rabbits, mice, hedgehogs and badgers. (Plantigrade)
  • Walk on the whole of their toes, like foxes and dogs, with the wrist/heel bones always off the ground. (Digitigrade)
  • Walk on the nails of the toes, or the 'hoof', like deer, cows and horses. (Unguligrade)

Animals which walk with the whole foot on the ground are usually slower. With more bones and joints in their feet, their legs are shorter and their feet are heavier. However all rodents such as mice and shrews are plantigrade and they have light bones and move quickly.

Flat hind foot of a Field mouse. The whole foot is just 1.9cm long x 0.3cm wide
Field mouse, heel bone!
Delicate front foot of a Common shrew. The whole foot is just 0.7cm long x 0.2cm wide.
Rat, hind feet, 3.5cm long

Small mammals like mice, shrews and voles have the tiniest bones in their feet. The main photo shows the almost-transparent hind foot bones of a Field vole

Field mouse, bones inside the fore foot. The whole foot is 0.7cm long x 0.2cm wide.

Many small mammals use their front feet to manipulate food.

Field mouse, tiny bones at the joints of the toes

Some mammals have large back feet and smaller front feet. They push off with the back feet when they leap up to escape danger. Examples are the rabbit, mouse and squirrel.

Field vole holding fruit ,while it chews

Animals which walk on the whole of their toes, 'digitigrade animals', often carnivores, can move faster and more quietly than plantigrade animals. They have longer wrist and ankle bones and more flexibility in their feet to seize prey. Predators like lions, dogs and foxes are in this group. Predators like the fox, use their sharp claws to seize and kill their prey.

Animals which run on the nails of their toes, the 'ungulates' or 'hoofed animals' are built for speed. They are usually prey animals. Over millions of years, some of their ankle/wrist and the finger/toe bones have fused into an extra leg bone, which increases the length of their stride. They are less stable than plantigrade animals but much faster. Horses have just one hoof and deer have two.

Bone inside a Fallow deer's hoof, 4.5cm long
Fallow deer, toe bones, like marble pillars!

Some mammals have evolved very specialised feet. The Mole has huge front claws which are shaped like shovels, for moving the soil as they tunnel through the earth. Moles have an extra, curved bone on the edge of their hand which extends the size of their claw. See the second photo, below.

Mole's hind foot and lower leg bones, 1.6cm long x 0.6cm wide
Mole's huge front foot, 1.8cm long x 1.5cm wide, with an extra bone on the side for more efficient shovelling!

Bats have extremely long, thin forearms and finger bones. Their wings spread out over these bones.

Squirrels have evolved long, lightweight bones for scampering around in the treetops. They can rotate their ankles 180 degrees, which means they can run headfirst down a tree with their feet pointing upwards for a better grip.

Grey squirrel's front feet, 3.7cm long including the claws and 1cm wide. See the cushioned pads and long claws.
Grey squirrels' hind feet, 5.5cm long x 1.7cm wide. They have four claws on their front feet and five on the back.

Squirrels have sharp claws to grip onto the bark of the trees as they climb and land after leaping through the branches.

Sharp claws of a Grey squirrel, 0.8cm long, perfect for gripping onto trees
Field mouse, tiny transparent claws, just 0.2cm long

Mammals which spend much of their life in water like otters and seals have specially adapted front limbs and feet. The otter has webbed feet, like a duck!

Otter, showing the webbing between the toes

Tail

The small bones in the tail are an extension to the spine. The number of tail bones, or 'caudal vertebrae' varies for different mammal species.

Foxes use their long tail for extra balance when pouncing and leaping

Some mammals, like squirrels, mice and rats have long tails to help them balance as they leap around. Rats and mice can climb ropes, run along fences and scamper up trees.

Rat tail bones, each about 0.8cm long
Black rat, showing the very long tail

Other animals like the hedgehog, rabbit and mole have relatively short tails.

Mole, tail vertebrae, each 0.3-4cm long. The whole tail is about 3cm long.
Hedgehog, tail vertebrae, each about 0.2cm long. A short tail, about 3cm in total.

The Collector, Photographer & Author

I am Susanna Ramsey and I have a unique collection of natural history objects relating to British Wildlife. Over the last ten years, I have assembled an extensive range of skulls, skeletons, bones, skins, feathers, wings, antlers, insect specimens and taxidermy, all from animals in the UK.

During 2010-2018, I took my Nature Collection into local primary schools to display and run workshops for the children, linking the exhibition to science topics in the National Curriculum such as Adaptations, Bones & Body Structure, Classification, Food Webs, Habitats, Life Cycles and Local Wildlife.

In 2018-2020, I worked with the leading schools' catalogue, TTS ,to create a range of Educational Resources for primary schools, nurseries, after school clubs and families. There are Look & Learn Cards for British Birds, Mammals and Minibeasts, a Food Webs Activity Pack, Classification Packs for Natural History & British Wildlife, Animal Discovery Bags for exciting wildlife trails, Playground Signboards and Identification Wheels. To find out more, scroll down or click here.

In the school workshops, children and teachers were always completely fascinated to see the bones inside the animals we see everyday, in the garden or local parks. On these web pages, I want to continue to share my enthusiasm for the skeletons of our local wildlife.

So much still to discover!

The photo above shows some of the 40 photo cards in the Classification Natural History Pack. (See below.)

Exhibits and Thanks

Almost all of the animals in my collection were either found by myself, Susanna Ramsey, or donated by friends and family to The Nature Collection, as an educational resource. Huge thanks for all the tiny, carefully-wrapped bundles of feathers and bones, to Steve & Sam Read, John Lock, Chris Matcham, Franko Maroevic, Tim Howard, Jan Wilczur, Simon Richards, Peter Veniard, Paula Redmond, Phil Davis, Bob & Sally Black, Jo & Frank Sheppard and Katie Ramsey. Many of these people are naturalists and experts in their field; I am indebted to them too, for all that they have taught me about our local wildlife.

Over the years, I have been lucky enough to be a regular visitor to the Angela Marmont Centre for UK Biodiversity at the Natural History Museum, London. The unimaginably-vast collection of British insect specimens, stored in row upon row, of metal, floor-to-ceiling cabinets has been a massive inspiration to me. There is something infinitely satisfying about the way every species has its own box, within a drawer, within a cabinet and that each can be found within minutes, by the care and expertise of the staff. To witness the incredible number of UK species of moth, beetle, butterfly, fly, grasshopper etc, is simply mind blowing and I feel so privileged to be able to visit and photograph some of the specimens!

I have used the photo stacking equipment at the Angela Marmont Centre to take highly-detailed photos of some of the specimens to put into slideshows for my primary school workshops. When I was young, I always wanted to be an archaeologist and it was my ambition to work in a museum; to sit in the Centre, using the equipment and handling the specimens, listening to the chatter of the experts at work, has been a dream come true. I am so grateful to the staff at the Centre for their encouragement and for always making me feel so welcome.

Thanks also to Tonja Grung, of Made from the Dead Taxidermy, for sharing her incredible knowledge, patience and skill. I will never forget our amazing sessions on animal taxidermy.

The delicate skeletons were cleaned to perfection by a colony of flesh-eating, dermestid beetles, skilfully managed by Edward de Geer.

Sources of Information/ Further Reading:

BRITISH WILDLIFE PRODUCTS

If you know children who are interested in nature, are a teacher, or would like to learn more about British Wildlife yourself, explore the range of British Wildlife products recently created by The Nature Collection and the leading schools' catalogue, TTS.

The Classification: Natural History pack features 40 small photos of animal skeletons, skulls, feathers, insect specimens and much more, all from The Nature Collection!

The photo opposite shows the Classification Boards in the Classification Packs.

The products are perfect for use in primary schools, nurseries, after school clubs, forest schools or at home with friends and family. Click on the links below to find out about each product.

Look & Learn Cards: British Birds, Mammals, Minibeasts

Food Webs Activity Pack

Classification: British Wildlife & Natural History

Identification Wheels: British Birds, Mammals & Minibeasts

Discovery Bags: British Birds, Mammals, Minibeasts

Playground Signboards: Birds, Mammals, Minibeasts

Some Look & Learn Mammal Cards. Facts are on the reverse.
Created By
Susanna Ramsey
Appreciate

Credits:

Susanna Ramsey