My crocodile and alligator skulls

This week I am going to write about two really unusually presents I got. Even though I still have loads of skulls from Scotland still to collect, it's still really nice to get skulls from other places in the world.

I got these from two different friends. Dad and I have checked CITES which says which animal bones can be moved between each country, and we think I am allowed to have these but CITES is a bit complicated, so I haven't named the people who gave me these in case I get them into trouble.

The head on the left is an alligator, and the skull on the right is a crocodile. Both are very young and small. The alligator head is about 12cm long, and the crocodile is about 9.5cm to the back of the skull.

You can tell the difference between alligators and crocodiles by looking at the shape of the skull.

Alligators (on the left) have a wide short u-shaped snout. Crocodiles (on the right) have a longer, thinner v-shaped snout. They look different sizes here but that's because they are both young, different ages, and haven't finished growing yet.

There is another difference with the jaws. Here is the crocodile's teeth:

The teeth of the crocodile fit in between each other, and point out a bit. Alligator teeth are different because the bottom jaw is smaller than the top jaw, so the bottom teeth sit inside the top teeth when the jaw is closed. Even though on my alligator head you can't close the jaws, you can see the holes in the skin on the top of the mouth where the bottom teeth go.

The alligator skin has been treated so the flesh doesn't rot. Alligator skin is used for a lot of things, like leather is, but even so cow skin rots when the cows die, so I expect alligator skin would too if it wasn't treated with something. It has fake glass eyes, and the skin on the bottom of the jaw has been taken away.

At the back of the skull, the back bits of the bottom jaws have been cut off, and it has been painted with thick black paint or tar. You can still see the knobbly bit where the top of the spine goes

The knobbly bit reminded me of the back of a T-rex skull at the museum in Paris I went to a few months ago.

Crocodiles and alligators are supposed to be the living animals most like dinosaurs. They haven't changed much at all. There is a display at Kelvingrove Museum in Glasgow which shows a crocodile skull from ancient times millions of years ago:

..and a crocodile skull from our era...

...to show that they haven't really changed much at all. That must mean crocodiles and alligators are very good at surviving and finding food if they haven't had to change much in millions of years. They can live a very long time. There is a freshwater crocodile in a zoo in Australia that is thought to be 130 years old.

The crocodile skull looks a lot like the alligator head because crocodiles and alligators only have a very thin skin over the bone. You can see the sticky out bits on the lower jaw which were cut off on the alligator.

There are tiny holes along the jaws. Scientists think these holes are where there are sensors to detect things int he water around them.

This crocodile was a baby, and it came from a crocodile farm in a country called Malawi in Africa. The crocodiles are bred for their skin which is used in making handbags, luggage, belts and shoes. The crocodiles are born just to be killed, the same as pheasants, cows, pigs and chickens here.

The back of the skull shows the hole where the spine goes into the braincase. The braincase isn't enclosed so you can see through the spine hole right through into the orbits.

The teeth are all the same design, unlike foxes, badgers, deer and sheep, where the teeth are different shapes and sizes. That's because crocodiles and alligators are homodonts which means "teeth are all the same"

This is a complete skeleton of an alligator at the Paris museum. You can see it's an alligator because the teeth overlap.It must have been eight or ten feet long.

This is a Nile crocodile that was at the zoo next door to the museum in Paris. It lay so still with its mouth open that mum thought it was a fake !

These are fantastic gifts to get, so thank you very much to the people who gave me them !

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