Last week I gave you another genuine mystery object to have a go at identiftying, from an archaeological dig by Irish Archaeological Consultancy:
As I suspected, quite a few people recognised this specimen. It’s a humerus with the distal articulation (that’s the elbow bit) intact and the proximal articulation (where it meets the shoulder) broken off.
The size and overall shape is similar to a small, robust human humerus, so at first glance it might suggest a primate, like a Chimpanzee or maybe a small Orangutan. However, the olecranonon fossa (the groove at the back of the elbow joint that the olecranon process on the ulna bone of the lower arm/forelimb locks into when the arm/forelimb is straight) is far too deep for it be from an ape.
Baboons, Geladas and Mandrills have a deep fossa, but the overall shape of their articulations is more cuboid than this, so there aren’t really any other primates large enough.
The shape is all wrong for an ungulate and most carnivore humeri have a different articulation shape and some diagnostic features that are lacking here. But, there is one type of carnivore that has a humerus this shape. This was not lost on many of you, both in the comments here and on Twitter.
The general similarity in shape with a primate humerus is due to a functional similarity in the use of the fore limbs. Unlike most carnivores, the animal this came from can stand bipedally and use its arms. Obviously I’m referring to a bear of some kind.
The type of bear is a bit harder to pin down definitively. It’s unlikely to be a Brown Bear, since it’s not really big enough. That also rules out Polar Bear. I think it’s most likely to be from an American Black Bear Ursus americanus Pallas, 1780, since the other species of a similar size have somewhat better developed supracondylar crests (the ridges on the sides that the muscles of the forearm attached to) it could be from, like the Asiatic Black Bear or Sun Bear.
Thanks for all your observations on this – I hope there will be some more exciting archaeological mysteries to come!
Zygoma 
Context, context, context! Where did the Irish Archaeological Consultancy dig this up? And what was an American Black Bear doing in that (presumably Irish?) place? Is this, maybe, from a dig at the ruins of the house of some eccentric Anglo-Irish nobleman with a passion for exotic pets?
Re: ” It’s unlikely to be a Brown Bear, since it’s not really big enough”
— Is that really so? Brown bear populations differ a great deal in size: European brown bears are much smaller than the U. arctic of the Rocky Mountains or Kodiak Island! I was under the impression that European Brown Bears were closer to the size of American Black Bears. For that matter, male bears tend to be lot bigger than females, don’t they? Would a female European Brown Bear really be bigger than a male Black Bear? (Those are genuine, not just rhetorical, questions: I’m afraid I don’t have any precise idea of what the various size ranges of bears are!)
Quick trawl through the internet didn’t turn up anything very useful about bear size comparisons (I’m a frustrated trawler, not. frustrated troller!). But bear size is VERY variable even within species, and size ranges of Brown and Black Bears overlap.
From the Wikipedia article on Brown Bears: “The smallest brown bears, females during spring among barren-ground populations, can weigh so little as to roughly match the body mass of males of the smallest living bear species, the sun bear (Helarctos malayanus), while the largest coastal populations attain sizes broadly similar to those of the largest living bear species, the polar bear”. So I would suggest that (assuming that the find was from Ireland and not from North America) maybe you shouldn’t rule out Brown… yet.
It’s a very good point – size isn’t necessarily a good indicator and shape is usually better.
There’s a great bone id resource I stumbed over here: https://boneidentification.com/bones/?_bone_type=humerus
They have Black and Brown bear humeri and although there are no hard diagnostic features to indicate either way, the relative proportions of the articulation seem closer to Black bear and the mystery specimen is lacking the foramen that is sometimes seen in Brown bears (but not always, hence it not being entirely diagnostic). So I’m sticking with Black bear!
Paolo–
Thanks for reply. Relative proportions and the absence of something that might have been there had it been a Brown bruin: fair enough– that’s two votes for Black that don’t depend on size.
For curiosity, where was this found?
Ah, if I told you, I’d have to kill you 😉
It’s still an active dig site, so I’ve been asked to not share the location. I can say that it is in the city of Dublin and it’s probably late 18th to early 19th century.