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How old was George ?

Jake


George is a roe buck skeleton that I found in the woods near the Roman fort a few weeks ago. When we collected the bones we found we had almost a complete skeleton, which is great. When I find bones, I try to guess how old the animal was when it died. This is how I worked out how old George was.



Clue 1: the teeth



Looking at teeth is one of the best ways to work out how old a deer is. George had all his molars and premolars which means he is not a baby. The third pre-molar on the bottom jaw is an important tooth (that's the one the arrow is pointing at). When deer are born, their third pre-molar is a baby tooth, and it has three cusps or spikes, at the top. George's tooth has two spikes, so it's the adult tooth, and roe deer only get this tooth when they are about a year or 13 months old.

The rest of the teeth feel sharp. Old deer's teeth get smoothed down, so George was probably not old.

So the teeth made me think that George was over a year old, but less than five years old.

Clue 2: the antlers



George had little stubby antlers, rather than proper antlers. They look as if they had finished growing, rather than if he died before they could grow properly.

A month ago I saw little stubby antlers like this on a young roe buck I watched in a wood near Gleneagles.

The roe buck deer we watched near Gleneagles is on the right. He would have been born last May or June, so he would have been seven or eight months old when we took that picture.

The stubby bits didn't look like antlers at all, just little lumps under the skin. Young roe bucks have those little stubs until they are 18 months old, when they fall off and their proper antlers start to grow.

Because George had these little stubby antlers, I don't think he was older than 18 months.



Clue 3: we'd seen it before



Maybe the best clue we had was that we'd seen it before. When I looked at my walking diary from last year, I saw that we saw the body in the middle of June, and we thought it had maybe died a couple of months before. But if it had died a couple of months before, it could only be eleven months old, and so wouldn't have an adult third pre-molar. Did we make a mistake ? We were just guessing, and in the hot summer animals bodies rot faster. Even so, I thought it must have died in May or June, and it couldn't have died after the 11th June.

Working it all out

Now I had three clues, I had to work out when it must have died. Dad told me to write out a chart, and tick the possible dates for each clue. So for teeth, I ticked every month from 13 months (June 2009) onwards. For the stubby antlers clue, I ticked every month from 6 months to 18 months. These two clues meant it had to be between 13 months and 18 months.

13 months was when we first saw the body in June last year. George couldn't be any older than that because if he was 14 or 15 months, he wouldn't have been dead by June 11th.

So putting all the clues together means George must have been 13 months old, and that he died in early June. It is strange he died in the summer, when there was plenty of food and warmth. Maybe he had a disease, or maybe he was attacked by an animal.

There was another interesting thing about George, but I will write about that another time and I have written about it here !

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2 comments :

paolov said...

Hi Jake,

don't just use the skull - the postcranial bones can give you clues too! Check the degree of fusion of the epiphyses (the end bits of the long bones) as well. If they are completely fused with no trace of the suture then this will be a mature adult, if there is still a bit of suture showing it will still be growing.

I must run now, but I'll get back to you with more information on how you can use the epiphyseal fusion as an indicator of age.

Jake said...

Hi Paolo !

I think the bones had stopped growing, but I don't know when that happens with roe deer. I think it might happen about one year old, but I'm not sure.

I wrote about the other bones here, and they look like they've stopped growing. There's a close up of the femur here that had a damaged growth plate.

I think I was wrong about the age because it looks so much bigger than my eight month roe skull.




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