As far as i know, there arent bigger animals around today due to the square-cube law, and yet their were dinosaurs the size of whales on land?
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The square cube law doesn’t mean you can’t have bigger things, it just means you can’t scale up an existing thing indefinitely and expect it to work.
The bigger animals, like the dinosaurs you’re thinking of, simply had differently structured bodies that allowed them to be bigger (more bone to body ratio, hollow bones…).
It’s not like an elephant is the upper limit for mammal size. If you took a mouse and made it as big as an elephant, it would also collapse. If you took a small dinosaur, and made it bigger it would also (probably) not work.
The square-cube law isn’t specific to biology, it’s just an observation about how volume grows faster (cubically) than surface (squarly), which also (usually) means that mass will grow faster than the support structure for that mass. An elephants weight is supported by its bones, muscles etc. If you scaled it up the bones would get bigger too, but the mass of the bones would get bigger faster, and at some point, it would get too much. If you wanted a bigger elephant, you’d need to change how much bone it has compared to It’s body size (not just how much bone it has compared to a smaller elephant). The reason real elephants can’t get any bigger is that when a new one is born, evolution doesn’t go on a character select screen and pick what kind of bone-to-mass ratio it would want. It’s stuck with what it has, at least for now.
Edit: Just to address this, because people keep posting bits and pieces of it in the replies: yes, the square-cube law has many more biological implications than just collapsing under your own weight because your bones and what not were not prepared to handle it. That’s just the most common thing you hear when people talk about it in popularization, because it’s kinda fun, in a morbid way.
One other thing that becomes a problem, and you can see this very well with elephants specifically, is that as you grow, you become to have cooling problems, since you gradually have less and less skin to disipate the heat, proportional to how much you’re producing. That’s why elephants have such huge ears. But there’s many other implications, such as not being able to absorb enough oxygen, because your lungs are too small, not being able process nutrients fast enough, because you don’t have enough gut surface… Really anything that has anything to do with the surface or cross section of an organ will become problematic if you scale an animal up or down.
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