I'm looking for some advice on classifying the specimen pictured above. It is a pentadactyl limb with retractable claws and measures around 150mm from end to end. I'm presuming it's from a larger cat, but I'd be really grateful for any tips on classifying species or whether this is a forelimb or hindlimb.
Thanks in advance for your advice.
This may not be as easy as it should be! The bone on the far left of the photo is a calcaneum which should mean that this is a foot. The digit closest to you in the photo has only three bones whilst the other digits which can be seen have four, this makes the closest digit either a thumb or big toe. If we assume it is a foot the calcaneum should attach through two other smaller bones to the Big Toe, in the photo the calcaneum appears to be attached to the third, fourth and possibly fifth toes (fingers). The wire connecting the calcaneum to the rest of the foot is of a different type to the rest of the wire, it looks like it has been added more recently and it is possible that the calcaneum is unrelated to the rest of the specimen. As I have identified this as a foot based on the calcaneum it raises the possibility that this could be a front paw.
Could you take another photo looking down on the specimen so we can see all the toes, differences between cats, dogs and bear (I think) are more obvious from this angle.
We can clearly see five toes, four have four bones and one has three bones - the big toe. Cats only have four toes in the hind foot, so this helps narrow things down. The lion and Leopard feet are much longer and slender than this foot, so I am thinging heavy animal or a digging animal rather than a fast animal. The feature that intrigues me are the bones supporting the claws which seem to get bigger and bigger towards the outside of the foot, this can only be a feature of a few mammals, someone must know which!
There are some 'small' bones missing which would attach the calcaneum to the big toe so I am happy with the new wiring now I have extra views.
The long twisted wire seen on the top new photo is often used when building a skeleton to raise the ankle off the ground and make the animal 'walk' on the toes. Mant animal walk inthis way, man doesn't - we walk on the whole foot. This will help to narrow things down as well.
More great insights, John.
Do you know, by any chance, what the technical name is for the claw supporting bone/sheath?
I'm still pretty stumped by this specimen, the protractible claws seem to suggest a cat, but only a polydactylism mutation or a mounting error could explain the 5th digit on the back foot.
Are you aware of any digitigrading burrowing animals which could fit the specimen? If not, the cats are really the only family I can think of to whom this specimen could belong!
I have directly compared this foot with Lion, Leopard and lynx and they are all very different to this specimen. They all have much longer metatarsals in comparison to thier width and the claw sheaths are as different. In cats the middle two toes arethe longest and have the largest claws whilst this specimen has five toes almost in a straight line with the lateral toe having the largest claw.
Looking at the fossil record ground Sloths have simillar terminal phalanxes. I have also been looking at Pangolin, anteater, badger, bear, panda, nothing quite fits yet.
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You mentioned viverrids as five-toed mammals with protracted claws. Binturong is the largest species, and sometimes kept as pet. I wonder if your specimen could be a binturong.