Paleontology question -- How could dinosaurs reach such massive sizes under the pull of gravity?

Update: [Maybe the question was confusing, but I found the answer now.]
Update 2: [Thank you, everyone. You do not need to post anymore. I got the answer.]
Update 3: [I found the answer at PBS Eons. 2017. "How Did Dinosaurs Get So Huge?" (October 2). YouTube.]
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