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The common bone hardly anyone has heard of


Here's a bone that's incredibly common, but hardly anyone has them, and even I had to look up the proper name for it. I have hundred of skulls in my room, so in theory I should have two of these for every skull, but I think this is the first pair of them I have. And like most animal bones, you will have two of these in your own body !

So this bone is flat, a bit like a bird scapula (shoulderblade). The ones I found are about 8cm long, and at one end look slightly like a rib, with a Y-shaped split. At the other end it is wider and curver, very slightly like a bird humerus, but much flatter. But this one isn't from a bird, but a large mammal. But before I tell you what it is, I'll tell you about how it was found.

It wasn't me that found this one, but dad, who went out in the week to see if he could track where my red deer herd had moved to, since they had stopped taking the path by my trail camera at night and in the morning. He went into the wood where we did the filming for CBBC Wild, checked the Suicides Graves clearing where I watched the rut last year, moved up to the moor, crossed the moor, then moved down into a wood we call Titus Well, and sat and ate an apple beside a huge clearing. 

He noticed two red deer moving across the west end of the clearing, and went to track them, and as he moved up he noticed a leg bone just inside the edge of the wood. 

It was from an adult red deer, it was a metacarpal (front leg) and the first two phlanges (toe bones) were still attached with soft tissue, so it probably was from the last couple of months.

A little further up he found this skull:

This was from a young stag with a tiny first set of antlers. It had five teeth in the lower jaw, but the first three were milk teeth. (An easy way to check is the third one pre-molar 3, which has three cusps or spikes when it is a milk tooth, but two when an adult tooth). The final molar at the back, M3 hasn't yet emerged above the jaw line and was covered by bone Using my guide to telling the age of a deer from its teeth, it was probably 12-18 months old when it died

The bits of this skull which pointed upwards were green from some like of algae growth inside the bone itself. That means it probably lay there for a couple of years.

A bit further up he found another metatarsal, this time with the ends unfused, which probably came from the same deer.

Then a bit further up still he found this:

It was a young adult red deer hind skull. An adult because all six adult teeth were through (about 30 months in red deer), a hind (female) because it had no antlers or pedicles (where the antlers grow from), and a red deer because of the size (30+ cm). There were also seven incisors (one missing) and some tiny bits of soft tissue, suggesting it was killed earlier in the year. 

There was also something very odd on the lower jaw which I hadn't seen before on a red deer skull, and which I noticed after he brought back the two skulls to show me:

The third tooth, an adult premolar (PM3) was an odd shape with an extra cusp (spike). And when I looked closer:

It was a tiny part of the baby premolar (pm3, in lower case) which had not been properly pushed out, and was jammed between PM3 and PM2. It you look closely, there is a gap between PM3 and PM2 and PM3 is lower than it should be.  This, and the sharp ridges on the top of the teeth, make me think that although this was an adult hind, she wasn't much older than 30 months.

Dad thought maybe it was a gamekeeper or a poacher had killed these two deer because of no other skeleton (post-cranial bones) nearby apart from the lower leg bones, and gamekeepers often leave behind the heads, lower legs and innards to reduce weight when taking the body back. 

 But the most interesting bits were just visible in that picture under the skull:

The big clue about what they are and where they come from is when you realised that if this was a shot red deer, the bones must be from either the head or the lower legs, since these were the only parts left behind, and since they were from the skull, that's where they are most likely from.

I sort of knew what they are, but the more I looked them up, I realised that I didn't know as much as I thought I did, and the internet didn't help much either. So what follows is what I do know, and a bit of guesswork, and I'll correct it if you let me know any mistakes in the contents.

I had seen this bone before in a dried bird head: a thin "V" shaped bone inside the lower jaw, which helps control tongue movement as well as attaching the voicebox in humans.. This bone isn't properly articulated with any other bone, so it usually comes loose and gets lost when a skull has no soft tissue.

The one guide which did help with mammals was the brilliant "Small Mammal Manual Manuscript" which is an amazing guide by Lee Post in Alaska (and which I'm going to do a post about properly later). It explains that in mammals the hyoid isn't one bone, but between five or nine delicate bones connected together in the hyoid process. This helped me understand why I don't often see these bones, which is because the bones are so small that they only get found for the very largest mammals, such as red deer.

There is very little on the internet about the hyoid process in deer, and what there is is aimed at academics, so I had to work out the rest myself. 

I knew it articulated with the earbone (bulla) on the skull and on the inside of the earbone, below the ear hole is a smooth area:

The actual skull they came from was mascerating so I just grabbed a spare spiker (young red deer stag) skull to compare. This seems to fit with the smooth wide end of these hyoid bones, which then point inside the mouth area and one part of the Y end pointing down.

But then I thought I'd better check with the actual skull they came from, and the groove in the bulla was much smaller, so the other end seemed to fit better. Here's what I think is the correct way round:

This would then, I think, make these them the styrohyoid bones (Lee Post's guide calls them the stylo-hyal bones, which is probably also correct, but has fewer Google results)

So that solves that mystery - I think. It's just strange this is the first pair I have found !

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Melanie said...

Great post! I had never heard of them before! Never even knew skulls had that. :-)

Jo said...

Fascinating, Jake. I think I've just located the hyoid process on a razorbill skull I've got on my desk, thanks to your post! You've demonstrated again just how much you can find out with a bit of curiosity and clever research. You've probably looked up the hyoid bone in humans – very important in forensic pathology.

Jake said...

I'd almost forgotten as well !

Jake said...

Yes ! If the horns are broken then someone has been strangled to death.

alex said...

neat! i've seen these with bird skulls rather often, as i feel like they're more obvious. they're a pain to articulate and sometimes locate (i macerate, so they are in a jumble at the bottom) so i haven't usually kept many of them. but a feral hog i am macerating has all of the hyoid bones in place... which is pretty astounding, given that the hog was shot right in the jaw!

Jake said...

It's impressive if they're all there in order !

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