On Friday I asked for help with identifying an object that I came across while working on the Horniman’s bird collections for our forthcoming Bioblitz review:

I must say that I was surprised at how many people came and checked out this post and offered suggestions – largely following a retweet from the excellent QI Elves. Many thanks to everyone who offered their suggestions. In this post I’ll look at some of the suggestions and let you know what I’ve narrowed it down to.

Here’s an annotated version of the image to help make my terminology clear:

There were quite a few suggestions of Moa, Ostrich, Emu, Cassowary or Rhea (which are all Palaeognaths), but this leg is way too small and although the hallux is reduced it is definitely there, whereas in the Palaeognaths the hallux is absent. Here’s the specimen alongside an Ostrich foot:

A Secretarybird was another common suggestion and it was the first possibility that I thought of myself. Secretarybirds use their long legs to walk the plains of Africa in hunt of prey, which they stamp and kick to death. However, when compared to a Secretarybird in the Horniman’s collection it proved to be different in the relative proportions of the tibiotarsus and tarsometatarsus and the total length to the toes:

Seriemas were also suggested – these birds fill the same niche as the Secretarybirds, but in South America. They have one short digit with a sickle-like hunting claw, almost like a Velociraptor, however the mystery object has fairly equal length digits.

Owls were suggested, but this leg is far too long to have come from any species of Owl. Here’s the specimen compared to the biggest (or second biggest) species, the Eurasian Eagle Owl:

The suggestion of Owl probably arose because of the curved claw, which also looks a bit like it might belong to an Eagle or Vulture. However, the bones don’t seem to be robust enough for any of these kinds of birds. The claw confused me quite a bit, since most of the remaining possibilities are wading birds that don’t have big curved claws. This led me to reassess the claw by straightening out the digit of the mystery object in Photoshop to see if the apparent curve and size of the claw is actually a result of the postmortem clenching of the foot:

When viewed like this, the claw seems proportionally smaller and less likely to be from a predatory bird, especially considering that with flesh and skin on the bone the claw would seem even smaller.

This realisation made me reconsider the long-legged birds that I’d discounted at first – in particular the Herons, Storks and Cranes. I did consider Flamingo, but they have webbed feet and an even more reduced hallux than seen in the mystery object. Conversely, Herons could be excluded because they don’t have such a reduced hallux:

Some Storks have limbs with the right sort of proportions – as helpfully summarised by henstridgesj:

The ‘FMO’: 1:0.73
Various Cranes: 1:0.7 – 1:0.8
Marabou Stork: 1:0.74
Maguari Stork: 1:0.75
Lappet-Faced Vulture: 1:0.63
Secretary Bird: 1:1
Flamingo: 1:0.84
Seriema: 1:0.87

But their claws seem too small and straight. That leaves the Cranes – as suggested by The Shonko Kid, André Rodenburg, henstridgesj and Skullsite’s Wouter van Gestel. This would fit the proportions of the elements of the leg, the length of the hallux and the size and shape of the claws. It would also agree with the highly ossified tendons – a trait common to Cranes.

So, I don’t have a specific answer for you this week (that’s two weeks in a row!), but I think this leg probably belonged to one of the Cranes. Thanks for your help in getting that far!