One Bone to Represent Them All: The Enduring Legacy of the Femur Bone

Note: This blog post includes some images of human remains.

Long time readers of this blog will know that Halloween is my favourite time to complain about skeletons – I mean, as much as I love to get spooky around this time of year, it’s hard to supress the professional urge to point out that spiders are not made out of bones like that, what the actual heck.

I hate you, skeleton spider. (Image Credit: Party City)

Instead of doing another post like that (although frankly, they seem to just make more and more of these horribly inaccurate animal skeleton decorations every year), however, I’ve decided to instead praise the bone that – besides the skull – seems to carry the burden of representing all bones, regardless of species, whenever a bone is required for decorative or fictional reasons.

Let us discuss the humble, yet everlasting, femur bone, folks.

A 3D model of a human femur bone (Image Credit: Tornado Studios)
The humble stock cartoon bone (Image Credit: Pin Clip Art)

Okay, so let’s first start off with the fact that the typical cartoon depiction of a bone isn’t a one-to-one recreation of a human femur bone. As you can see in the images above, the standard cartoon bone has a long shaft akin to the actual femur bone, but the epiphysis on both ends are exactly the same. These identical ends are arguably based on the rounded distal end (aka the bottom part) of the femur; in real life, the proximal end (aka the top part) of the femur is mostly represented by the greater trochanter, neck, and head (see image below). That said, the stock cartoon bone is definitely based on the femur, regardless of how (in)accurate it is – I mean, even TV Tropes agrees with me!

The proximal end of a femur bone (Image Credit: Teach Me Anatomy)
This is a set of “mini bones” from Party City – notice anything about all of them? (Image Credit: Party City)

But why is the femur bone – or, well, some fictional bone that is mostly a femur bone – our go-to image for all things bone-related? This isn’t just limited to cartoons, either – as you can see in the image above, if you’re buying bone-related Halloween decorations, you’ll probably end up with a load of femur bones for some reason! Oddly enough, TV Tropes actually provides a pretty solid explanation: as the femur is one of the strongest and straightest bones in the body, it is often the most preserved and therefore the most recognisable. And this is backed by osteological research as well: for bipedal human bodies, the femur needs to be the strongest bone as it carries all of the weight during most physical actions. The strength of this bone, as well as the density, ultimately leads to it often having a better chance of survival in the archaeological record (White et al. 2011 p. 241). In addition, this strength and associated durability lends itself to the usefulness of the femur as material for creating tools and other artefacts (Christidou and Legrand-Pineau 2005, p. 394) – in some ways this is echoed in other popular culture depictions of the stock bone as a weapon or a spooky staff, etc.

Comparison of various femur bones from different species (from left to right): mouse, rat, rabbit, dog, goat, sheep, pig, South African monkey, rhesus, baboon, and human. (Image Credit: Joseph C. Wenke)

I would also argue, of all the different sort of bones, the femur is more or less recognisable across most species. Although there is obviously variation in size and in some shape (see the comparative image above), the main components are pretty recognisable: the long shaft, the bulbous head and raised greater trochanter…you get the picture.

So, this Halloween, remember to salute the femur bone for all of the hard work it does, not just as a long bone in the body, but also as an ambassador, serving as a role model for all bones, everywhere.

Maybe one day you’ll get your proper due, astragalus bone…

The astragalus bone is my favourite bone of all time and I’ll fight anyone who says otherwise.

References

Anonymous. Stock Femur Bone. TV Tropes. Retrieved from https://tvtropes.org/pmwiki/pmwiki.php/Main/StockFemurBone

Christidou, R. and Legrand-Pineau, A. (2005) Hide Working and Bone Tools: Experimentation Design and Applications. In H. Luik, A. Choyke, C. Batey, L. Lougas (eds) From Hooves to Horns, from Mollusc to Mammoth: Manufacture and Use of Bone Artefacts from Prehistoric Times to the Present, Proceedings of the 4th Meeting of the ICAZ Worked Bone Research Group at Tallinn, 26-31 of August 2003. pp. 385 – 396.

Muschler, G., Raut, V., Patterson, T., Wenke, J., and Hollinger, J. (2009) The Design and Use of Animal Models for Translational Research in Bone Tissue Engineering and Regenerative Medicine. Tissue Engineering Part B, Reviews 16(1). pp. 123-45.

White, T. D., Black, M.T., and Folkens, P.A. (2011) Human Osteology. Academic Press.

Bones That Look Like Other Bones: Rodent Bones VS Bird Bones

Today’s comparative mini-post comes from a question I received from Trisha J. (thanks Trisha!),  who asked for a bit of a comparison between rodent and bird bones. Now, while I have written about both rodents and birds before, I’ve never actually compared the two in one of these posts – which is a bit of a surprise, as I totally get the confusion between them! They can look pretty similar,

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Herring gull skull (left) and brown rat skull (right)

Before we start, let me first preface this by saying we’ll be looking specifically at small bird bones – obviously, as you can see in the photo below, birds come in a wide variety of shapes and sizes! So we will be working under the impression that it’s easier to confusion small bird bones with rodent bones…unless you’re working with Rodents of Unusual Size, I guess?

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Herring gull humerus (left) and corvid humerus (right)

Unfortunately there isn’t an easy tip for differentiating between bird and rodent bones quickly – although bird bones are known for being particularly light in weight to allow for flight, rodent bones have a similar weight due to size. Thankfully, bone shapes are pretty distinct between the two. See some of the example photos below to see how each differ!

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Corvid humerus (left) and brown rat humerus (right)

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Corvid femur (left) and brown rat femur (right)

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Corvid ulna (left) and brown rat ulna (right)

If you’re dealing with bone fragments that are similar in size to either a small bird or rodent, I would highly suggest using some form of reference (photo or physical) to base your identification off of. They can certainly be quite tricky! You can also use small variations, such as the presence of “nubs” on bird ulnae, to help differentiation. Also remember that birds have bones that are not present in rodents (tibio-tarsus, furncula, etc.), so memorising their general shape will be helpful.

With skulls, if you have complete specimens, it’ll be pretty easy – the bird will usually have a beak attached!

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Corvid skull (left) and brown rat skull (right)

Of course, life isn’t fair and you will often have a skull fragment on your hands. In that case, remember that bird skulls, in particular the cranial vaults, have very rounded and bulbous skulls (see below).

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Jackdaw (bird) skull fragment

And if you’re unlucky enough to have vertebrae and ribs on your hands…well, good luck! Well, maybe at least with the ribs…vertebrae can be very tricky, especially when they’re very small. However, bird vertebrae tend to have a “body” (the thickest part of the vertebra) that curves inward and are a bit more narrow in shape.

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Corvid vertebra (left) and brown rat vertebra (right)

Have a question about zooarchaeology? Or an idea for a future blog post? Remember you can contact me through the blog by heading to my Contact page.

References

Cohen, A. and Serjeantson, D. (1996) A Manual for the Identification of  Bird Bones from Archaeological Sites. Archetype Publications Ltd.

Prehn, N. et al. (2018) Beginner’s Guide to Identifying British Mammal Bones. Natural History Museum. http://www.nhm.ac.uk/content/dam/nhmwww/take-part/identify-nature/british-mammal-bones-ID-guide.pdf

Bones That Look Like Other Bones: A MiniPost About Rabbits and Hares

Note: Is it morbid to look at rabbit and hare skeletons on Easter? Maybe. But more importantly, please remember that caring for rabbits as pets is a commitment – don’t buy them as an Easter Day gift for kids if you’re not committed to caring for them! More information can be found here.

So, moment of truth: how long did it take you to realise that rabbits and hares are two different animals? I’m pretty sure I was hitting double digits in age before that dawned on me…embarrassing? Maybe. But it’s an easy mistake to make: rabbits and hares look extremely alike! And that’s not just limited to their outsides either…today’s mini comparative anatomy post is about the bones of hares and rabbits!

Good rule of thumb with differentiating between hare and rabbit bones is to look at the size of the bones – hares are generally larger than rabbits. This is definitely noticeable just looking at the skulls of a hare (on the left, above) and a rabbit (on the right, above).

Hares also have larger, stronger hind legs, which can also be easily seen when you compare these bones to rabbit bones – in the above photo, are two femora, with the larger and more robust femur belonging to the hare.

Despite being from different species, however, both rabbits and hares do share similar physical traits in their skeletons, with explains why some archaeologists may have some confusion when it comes to differentiating between the two (for example, compare the two tibia bones above – besides the difference in size, they’re rather similar!).

If you’re interested in more archaeological work on hares, check on the Exploring the Easter E.g. project undertaken by the AHRC and the University of Nottingham!

References

Elena, S. (2008) Rabbits and Hares: No More Confusion! http://www.orcca.on.ca/~elena/useful/bunnies.html

Langley, L. (2014) What’s the Difference Between Rabbits and Hares? National Geographic. https://relay.nationalgeographic.com/proxy/distribution/public/amp/news/2014/12/141219-rabbits-hares-animals-science-mating-courtship