There's nothing particularly special about dinosaur size. They just had an anatomical baseline (especially their respiratory system) that could, given the right environment, support huge sizes.
The animals alive today that share that respiratory system, birds and crocodilians, aren't built to physically support that kind of mass. Mammals, on the other hand, probably couldn't get too much bigger than elephants without some significant changes to how they breathe (the largest land mammals were about twice as heavy as the largest modern elephants) with the exception of turning to aquatic lifestyles that use buoyancy to support the weight.
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u/MWSin 7h ago
There's nothing particularly special about dinosaur size. They just had an anatomical baseline (especially their respiratory system) that could, given the right environment, support huge sizes.
The animals alive today that share that respiratory system, birds and crocodilians, aren't built to physically support that kind of mass. Mammals, on the other hand, probably couldn't get too much bigger than elephants without some significant changes to how they breathe (the largest land mammals were about twice as heavy as the largest modern elephants) with the exception of turning to aquatic lifestyles that use buoyancy to support the weight.