Looking closely at an Indian elephant skeleton

On Thursday dad and I went to the Hunterian Museum of Zoology which is part of the University of Glasgow. I'm going to write more about it later but for this post I'm going to focus on just one exhibit, their juvenile Indian elephant skeleton (the scientific name is Elephas maximus indicus).

There are two different types of elephant, which are the African and Asian. The Indian elephant is one of the three subspecies of the Asian elephant (the other two are the Sri Lankan elephant and the Sumatran Elephant). The African and Asian elephants look quite similar, but African elephants are larger with much bigger ears and tusks.

I must have seen elephant skeletons before, but the one at the Hunterian Museum of Zoology was nice because you could go right up to it and touch it.

The difference between the African and Asian elephants skulls are the shape of the tusks, and the dent in the top of the head which Asian elephants have but African ones don't. The hole in the forehead might have been where it was shot:

The tusks are the upper incisor teeth which have just grown massive. They keep growing the whole life of the elephant and they grow 15-18cm a year, which would have made this one about five or six years old (elephants live for about 60 years).  Female Asian elephants have much smaller tusks (or none at all), but both male (called bulls) and female African elephants (called cows) have them. Having tusks looks cool but the ivory is valuable, and elephants are hunted and killed by humans just to get the tusks. This sucks.

Elephants tend to use one tusk more than the other, so one ends up being more worn. Sometimes it's the left, sometimes it's the right one.

The entrance to the ear bone is just like a small hole, and I couldn't see the ear bones:

Elephants have very flat faces, with no nose forward of the tusks, and the forehead directly above. Elephants have no lower incisors or canines, and the jaw ends right after the pre-molar (cheek) teeth. The skull looks different to the face because the elephant's trunk has no bones inside, and works just on muscles. Here is a real Asian elephant and the Huntarian's skull side by side:

Elephants use their trunk to get food and water (African elephants use their trunk to get leaves from trees, Asian elephants mainly eat grass, bamboo and fruit). 

An adult Indian elephant has a dental formula of I: 1/0, C: 0/0, PM: 3/3, M: 3/3 which means on each side of its mouth it has one upper incisor (tusk) but no lower ones, no canine teeth, then three pre-molar and three molar teeth at top and bottom, which makes 26 in total. It is quite difficult to see the gaps between the teeth, so it looks like one huge tooth. The flat teeth are similar to other herbivores like sheep and deer which need to really grind the food to get nutrients. 

Like us elephants replace their teeth, but with our jaws the new tooth comes from underneath, pushing the old tooth out. With elephants, the new teeth are grown at the back of the jaw, then they get pushed forward as the old teeth fall out. You can see this at the back of the jaw:

Unlike say deer, which eat leaves and grass but which have a long neck to bend down, elephants don't need a long neck because of their trunk, so their neck vertebrae are quite thin (you can see it in the picture below). The short neck probably makes it easier to support the heavy skull. The skull is also made lighter by using a honeycomb structure rather than solid bone, similar to bird bones.

The scapula is triangular with a large ridge (called the scapula spine) with two hooks on it at the shoulder end for muscle attachments. Elephants don't need clavicles (collar-bones in humans) because their legs don't go at a wide angle from the body, so the extra support isn't needed. They are big heavy animals, and their weight goes down straight through the legs which are almost vertical:

This is the humerus (upper arm bone) seen from in front. It isn't quite as thick as you might expect, but it is very wide at the elbow end for muscle attachments. The head of the humerus, which is the bit where it attaches to the scapula, isn't very big, because the forelegs are never at much of an angle to the body, they are pretty much always straight down.

This is the top of the humerus. The bit that looks like a horizontal crack shows it was a young animal where the bones were still growing. In older animals, this would have fused on.

This is the lower front leg with the radius (on top) and the ulna (below) which look more twisted than other animals, but this is probably just because the radius and ulna are shorter and thicker than other quadrupeds.

Elephants feet aren't flat (like rabbits) but they balance on tiptoes, like sheep or deer, but it's hard to see this because elephant feet are surrounded by flesh, and look flat and round. The fleshy bits underneath make it easier to stand up for a long time. They have three main toes, with two smaller ones behind.

This is from the bum end. The pelvis looks very wide here (like Megatherium), and you could see where muscles would attach between the femur (upper leg bones) and pelvis.

The marks at the top were old holes where it had been mounted before. It was obviously an old skeleton that had been rearticulated several times.

The tail has over 20 bones (caudal vertebrae) which is quite a lot when you think the elephants tail doesn't seem to need it for balance in the same way other mammals use it (like cats), but they need their tail to swat flies:

The elephant has been rearticulated with spaces between the vertebrae where the discs of tissue would have been (I should have done this with Vulpy too). If they hadn't have done this, the elephant would have been wrong, and much shorter.

This elephant has 20 pairs of ribs, which is a lot. The first rib was very thick indeed:

There was one final thing which I thought was quite weird, and I thought they had got wrong. You can't really see it in this picture, but both the front left and back left feet are off the ground at the same time ! This seems like an impossible way for it to walk:

But then I found this set of photographs which show how elephants move, and they really do walk like this !

(Animation from still photographs by Edward Muybridge, and the photographs are now out of copyright, via Wikimedia Commons)

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