# Size of a dinosaur's thigh

What is the best-guess diameter of the larger land-going dinosaurs’ thighs? Something like an apatosaurus.

I’m trying to figure out how strong dinosaurs were compared to other animals, and I’m using the leg because you wouldn’t want to base a T-Rex’s overall strength on its arms.

I know that size doesn’t really equate to strength, so I’m open to any other ideas for determining roughly how strong the various animals are.

You can get an idea of how large muscles were by looking at the attachment areas on the bones. I would suggest looking at a good scientifically based reconstruction, then measuring the thigh and calculating its width proportional to the length specified for the animal.

Obviously the strength of the muscles has to be sufficient to move the weight of the animal. (Although earlier it was assumed that the big sauropods were too big to be able to support themselves on land and were therefore mostly aquatic, this idea has now been dismissed.)

The musculature and skeletal structure of T. rex has been the subject of considerable analysis and controversy relative to whether it could run fast or only amble along. Different analyses have come to different conclusions.

So I can just use the bone. Awesome! Thanks, Colibri!

In the application of the square-cube law to biomechanics, the usual assumption is that muscle and bone strength is approximately proportional to cross-sectional area.

While this is true to a first approximation, I should say that other considerations can come into play, such as where the muscle is attached on the bone (providing leverage) and the kind of muscle fiber involved.

Remember that almost every animal is stronger for its size than a human, because humans carry a mutation that makes our muscles much less efficient.

Also bear in mind that dinosaurs were almost certainly active animals, with a high rate of metabolism. They are more likely to have been birdlike in their movements and alertness than lizard-like.

I don’t know how you’re measuring strength – are they lifting something? In general terms, the answer should be “enormously strong.” Tyrannosaurs Rex is believed to have had the strongest bite force of any land animal.

Measuring it very generally. Like “A T-Rex was x-thousand times stronger than a cottontail rabbit” or “A gigantopithecus was y times stronger than a modern chimpanzee.”

It’s slowly dawning on me that it’s simply not possible to calculate, even on very general terms. Kangaroos, for instance, have that unique musculature that makes hopping their most efficient means of locomotion, and the very powerful alligator has those spindly little legs.

It isn’t like you have any other choice–the bone is all that there is to work with.

You might find some useful articles at SV-POW!, such as this one.

Cite? I thought we just had a disadvantage of structure (how the bones are laid out and where the muscles connect to them) as compared to, for example, a chimpanzee.

Some fossils include tendons, and there are a few rare “dinosaur mummies” that include other soft tissues. But yes, for most species we only have bone.

Chimps aren’t as much stronger than humans as “common knowledge” claims.

Great cite, Darren.

We even had a thread where we discussed this at greater length.

But double is still pretty significant.

“A chimpanzee had, pound for pound, as much as twice the strength of a human when it came to pulling weights.”