Mass per volume is density, and I suspect the Trex and kangaroo are similar (~1000 kg/m^3) so yes they’d both bounce in that case. I think what you’re looking for is surface area to volume, which decreases rapidly as an object gets larger while maintaining geometry.
It’s worth noting that most extinct dinosaurs were probably more similar to surviving ones (i.e., birds) than to mammals and reptiles when it comes to bones and respiratory systems, and, by extension, density.
That is to say, they probably could get that big because they were quite literally full of air.
Some of them (especially sauropods, but maybe also other big species like tyrannosaurs) probably had even more complex and efficient air sac systems than modern birds…
Mass per volume is density, and I suspect the Trex and kangaroo are similar (~1000 kg/m^3) so yes they’d both bounce in that case. I think what you’re looking for is surface area to volume, which decreases rapidly as an object gets larger while maintaining geometry.
It’s worth noting that most extinct dinosaurs were probably more similar to surviving ones (i.e., birds) than to mammals and reptiles when it comes to bones and respiratory systems, and, by extension, density.
That is to say, they probably could get that big because they were quite literally full of air.
Some of them (especially sauropods, but maybe also other big species like tyrannosaurs) probably had even more complex and efficient air sac systems than modern birds…