Why were dinosaurs able to grow to an extremely large size when today an elephant (largest land animal) is only a fraction of the size of the largest dinosaur?
Yes, TODAYS ELEPHANTS.
But the largest animal EVER is the Blue Whale, alive today.
And mammals had some pretty big creatures too.
This is the Paraceratherium, a species related to rhinos
compared to largest dino ever
and here the largest elephantine ever
One possible reason to allow dinos to reach such large size is their bones… they were hollowed in the interior but very dense in the exterior.
This meant that for the same weight and size, a dino bone was STRONGER.
So, dinos could grow larger before their bones would crumble under their own weight.
Land mammals reached the bone size limit for our type of bones.
If some mammal lineage suffers a mutation and gets bones such as those of dinos, there is a possibility that in some dozens of millions of years, we might have mammals as big as the largest dinos.