Rib size to body size conversion

In lots of barren, deserted or otherwise destroyed landscapes, there are bones of long dead animals to be found. Sometimes, it's a skull, sometimes, these are rib-cages, or ribs alone.

And sometimes, these bones are huge.
Is there any sort of common ratio that can be used to calculate the size of the whole body of the animal dead from the size of the bone alone.

(Or more specifically, suppose I have a rib sticking 500 m into the sky, coming from the stereotypical flying flame-breathing dragon, probably western style (though eastern is fine too). Ignore the obvious "dragon of such size could not possibly fly"; I'm making up a game lore, not a documentary. Also, magic.)

• So I just googled a lot trying to find a RIB LENGTH for a human being and FOUND NOTHING. Hopefully you are lucky and someone finds a rib length, otherwise, you may just want to make a length up. May 2, 2019 at 21:49
• @AWriter: You seriously need to refresh your Google-Fu. For example, Damien Subit, Baptiste Sandoz et al., "Rib length variation with age and sex", in Proceedings of the 24th Enhanced Safety of Vehicles Conference, Gothenburg, 2015. (The example is intentionally obscure. One would normally look for such data in a textbook of physical anthropology.) May 2, 2019 at 22:37
• I have read somewhere that deducing the appearance of live whales from their skeletons is difficult and that their heads and torsos often extend beyond their skulls and ribs. May 3, 2019 at 16:36

The size of rib varies depending on the general physiology of the animal; an animal with big lungs and a heart is going to need a different rib cage from one with smaller organs; a biped's is going to be different from a quadraped's, and so on.

For comparisons, a blue whale has a rib cage that is perhaps a tad 2 meters deep (not individual rib length) in the biggest animals: here's an image of a man standing inside a mounted skeleton.

This is the largest reconstructed (and sizes mostly estimated) dinosaur skeleton in the world, an Argentinosaurus at almost 40 meters long and 7.3 meters tall at the shoulder. Based on those measurements, you can see the rib depth looks like it's about 3 meters for the longest ribs.

If we project similar proportions, for a rib sticking 500 meters into the sky, you'd be looking at an animal 6.7 kilometers long.

That's, um, a lot of magic. For another comparison, the largest sandworms on Arrakis, true monsters, were indicated to be 450 meters long. Godzilla Earth, from the 2017 animated film and the largest version of the Big G to ever appear, was 300 meters tall and 600 meters long.

• "But he grew tired, and so he laid to rest. A rest for eons, a rest that seemed it will never end. But a time come, and he woke. But he did not wake on a stone floor, where he laid. Oh no, he didn't. He woke buried under dirt, and shaken it off, he looked around and dismayed. For nowhere was seen the lakes of magma, the stone he knew. All around there was a forest, a forest deep and old, a forest of trees never cut. And between them some little folks stood, looking up to him. 'Praised be, You, whose skin gave this world its dirt and whose scales gave this world its trees. Praised be you, who May 3, 2019 at 18:37
• gave us live!' they shouted at him. And that was the moment he knew he were where he wanted to be. This world was all his, and he will make sure to protect it" "World" is basically a huge cavern (ignore source of sunlight and fresh air etc. - there is like REALLY lot of some forms of magic) - think 4-5 months of travel by foot if you are one of the elves of the world, and those can move fast Given the settings, I'm afraid a dragon 6.7 km long (+ tail, I suppose) might still be too small Anyways, making myself reminder to accept this answer tomorrow if none better comes (unlikely). May 3, 2019 at 18:41
• I worked on a Supersaurus one of the few large sauropods with complete ribs and they were 3 meters tall for a 33 meter long 32 metric ton animal. so this is reasonable.
– John
Nov 18, 2023 at 1:11