Multi-part question about muscle, fat, whales, and dinosaurs

#1 - I’ve always heard people say that “muscle weighs more than fat.” Is this true?

#2 - Is the blue whale still considered to be the largest animal that ever lived?

#3 - by “largest” animal I assume that people are going by weight, considering that there are jellyfish longer than blue whales. Is that correct?
I was just wondering about this because I was thinking that dinosaurs must have had tremedously dense muscles in order to support all that weight and still be able to move at reasonable speeds. Whales, on the other hand, don’t have to support as much weight since they live in water and, AFAIK, they have a tremendous amount of fat (probably to keep warm and help stay afloat.) So, if muscle does in fact weigh more than fat, is it possible that a slightly “smaller” dinosaur actually weighed more than todays blue whales, and was therefore actually “larger”?

I’m sure scientists have taken this into consideration when doing their estimates but I just had to ask because it will keep bugging me until some wise guy tells me why I’m wrong.

Umm, muscle weighs more than fat…that’s right, but not so much more that the difference between the largest dinosaur and the blue whale would be overcome by muscle weight.
You are kind of answering your own question: Blue Whales ae by far the biggest ever because they live in water and can handle all that weight.

Much arguement about how some dinosaurs stood/ran/lived is centered around the fact that the muscle is so heavy and would have to be so large in some areas that the nature of T-rex and other hunters (speed, hunter/not hunter, scavenger?) is debated.

It seems unlikely that a land animal would approach the size of the blue whale because of the weight of the muscles a land animal would need to support it’s massive size.

muscle is denser than than fat.

Sauroposeidon (translation: Lizard Earthquake God)- Height: 60 feet, Length: 100 feet, Weight: 60 tons

Blue Whale- Length: 72 Feet, Weight 70 tons

Philster, it’s believed that giant sauropods were able to live on land and water because they used their massive tails as a counter balance to their massive necks.

As for dinosaurs, weight estimates are generally based on an “average” density. If an elephant, for example, has a certain weight for a given volume, then if we can determine the approximate volume of a dinosaur, then we can extrapolate an approximate weight. Often, dino volume is determined by sculpting a model (as accurate as possible, based on known information), then submersing it. Assuming an average density for terrestrial vertebrates, then, the weight is estimated.

Note, however, that the large dinosaurs (such as the sauropods) had many weight-reducing features, such as light, scaffolding-like bones (as opposed to dense mammalian bone).

As such, determining weight for these giants involves a bit of guesswork, as well as science. However, even the upper-end estimates for some of the largest dinosaurs (e.g., 100 tonnes for Argentinosaurus) are still below the blue whale’s 130 tonnes, blubber and all.

And cainxinth, sauropods were not amphibious.

“Largest” in this context seems to mean weight and volume, which are of course fairly closely related.

Yes the masses of dinosaurs are often based on displacement… you make a model of a mmmiiikkkeeesaurus, lower it into some water, and see how much water it displaces. I beleive water is used since most animals have about the same density as water.
Take the volume of water displaced (say 1L), and multiply that by the model’s scale (say 1:1000), and you can say that mmmiiikkkeeesaurus weighed about 1000kg; add some fancy alterations for some variables perhaps as well. But then it all depends on the model which is at best a guess.

The biggest animals are usually measured by mass - giraffes are much taller than elephants but of course elephants are “bigger”.

There may have been some extinct sea creatures bigger than blue whales, but evidense of them is very hard to find. I guess the blue whale is still considered the largest animal that ever lived [that we know about], but I find it difficult to accept human statements about the biggest/most anything that EVER was seeing as how we’ve only been looking for a few hundred out of a few billion years.

I wasn’t implying they were. I said they were able to live in land and water, not breathed air and water. I was under the impression that sauropods spent much of their lives in the water, but according to this article that’s a fallacy. But it does say that at times they ventured into the water, when crossing a lake or river. So, sauropods were able to live in land and water, just not in equal amounts as my earlier statement implied. I apologize for the error.