My (almost) elephant skull

If you were asked what the two closest living relatives are to the elephant, you would think along the lines of something grey, hard-skinned and massive, and so guess that it might be a rhino or a hippo. The other close relative to the elephant is the sea cow - that's manatees and dugongs - which are heavy and grey, but they are aquatic. The other one is much harder to guess !

It all came about because of a visitor to my blog who also runs a taxidermy business in South Africa called Blue Duiker and who very kindly asked if I would be interested in a skull from there ! So a few weeks ago I was sent the skull of one of the closest living relatives to the elephant - and it arrived in a much smaller box than you might think ! That's because the close relative to the elephant is in fact:




.....a rock hyrax !

It's pretty clear that a rock hyrax does NOT look like an elephant ! So what is a rock hyrax anyway ?

The rock hyrax (Procavia capensis) is a pretty amazing and slightly strange animal that lives in Africa and in the Middle East. Adults can grow up to 50cm long and can weigh up to 4kg - which is cat sized - and they have thick brown fur which covers their body and have they have whiskers like a cat. They are group animals that live in large families, that feed together and post lookouts, similar to how meerkats live.

Teeth tell you a lot about what an animal eats, and it's pretty obvious that the rock hyrax's teeth are quite different from canids or felines. At the front they have the two long "tusks" of teeth, which look like an elephant on the skull, but are hardly visible in the living animal. I took out one of the long incisors, and it is very similar to the incisors on a rabbit, in that it is very long inside the skull, so that it constantly wears down and regrows at the same time. 

(If you're wondering if the teeth are like those on rodents such as a squirrel or a beaver: they may look similar, but rodents have an orange outer layer on the front part which keeps the teeth very sharp. Rabbits are from a different family of lagomorphs)

The back teeth show the rock hyrax eats a wide variety of plants and insects, because they are best at grinding. The dental formula for a rock hyrax is 

1.0.4.3

2.0.4.3 

That means on the top row of teeth, going from the mid-point at the front of the skull and working back, it has 1 incisor, no canines, 4 pre-molars and 3 molars per side. On the bottom it is 2 incisors, no canines, 4 pre-molars and 3 molars. The pre-molars and molars look very similar, getting progressively bigger towards the back of the jaw.

Here you can see the bottom jaw. It may seem odd that the bottom jaw has a different number of incisors, until you remember cows, sheep, and deer all have bottom incisors, but no top ones.

This skull is slightly under 10cm long, and the top part sits at an angle when on the lower jaws because the back part of the jaw is incredibly thick.  I've never seen a jaw quite this thick at the bottom edge before,  although horses are slightly similar, and I think it's because it's a good adaptation for grinding. If it meant it had a strong bite, it'd have a ridge on top of the skull - a saggital crest - for the jaw muscles to attach to.

You can also see the gap between incisors and back teeth which is a sign of an animal that grazes, and also how the top and bottom incisors come together:

From the back you can see how deep the jaw is. This is very unusual and from the side reminded me slightly of a howler monkey jaw, although the howler monkey has a very special adaptation for that, which is different when seen from other angles to the rock hyrax.

Here's the top view. As I mentioned before, since it is not a meat eater, it does not need strong jaws, so it does not have a saggital crest. The tiny plate in the middle is unusual. as is the narrow snout, which is presumably so it is better at finding insects and food. It's slightly armadillo-like from this angle.

So the rock hyrax skull looks a lot like a lot of other skulls in part: there are bits that look like horse, howler monkey, sheep, rabbit, armadillo, and elephant, even though it isn't really like any of those other creatures, and I think the similarities are sometimes coincidences. It's amazing that an animal so common in Africa is so different from all the others, and it shows you even the most common animal can have amazing features.

A BIG thank you to Philippe from Blue Duiker for sending this to me ! There was also a second skull in as an extra present, but I'll write about that another time !

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