I’ll be keeping this one short as there is really not much to say, however the photo is a really nice example of how extreme some bits of soem organisms get. While obviously there are some huge bones out there in various organisms (typically revolving around whale and ceratopsian skulls and the odd sauropod humerus) there are also some less likely candidates for biggest (well, OK, longest) bone of the vertebrate world – step forward the cervical rib.
This particular one is on display at the IVPP in Beijing and is to my knowldge the best and most complete of its kind. It comes from a specimen of Mamenchisaurs and is a staggering, wait for it, 3.2 m long! Thats right, over three metres and close on 11 feet. For a rib. That fits in the neck.
Not surprisingly things like this are not the easiest to find and preserve badly, you can’t see it in the photo, but there is a huge amount of glue holding it together (though it is definitely one piece) as it was essentially shattered when found. Still, it is a real demonstration of pushing simple bones to extremes and raises some interesting questions about the most basic mechanics of these animals. Mamenchisaurs has one of the most extreme necks of sauropods as it is, and support is an obvious function for a rib of this kind (you can see how straight it is, and that it would be held alongside the neck, and presumeably would overlap with the ribs of other cervicals). Still, it begs the question, how on earth did the neck flex with that buried in it, and if the neck did bend, was the rib pliable enough to bend itself? It is a complex question associated with a single simple rod of bone – science can be damned frustrating at times, but half the fun is finding out.
Incidentally, the feet in the frame are those of Mamenchisaurs, not the same animal but a reconstruction of one that was probably similar in size, which gives you a feel for just how big that thing is.