Dinosaur dogma

Just a couple semi-random questions, because I’ve been discussing these issues with friends.

Question the First
Is the Blue Whale really the largest animal that has ever lived on Earth? This statement dates back from the days when Brachiosaurus was considered the heavyweight of the dinosaurs, and it would have been true then. Blue whales average 25 meters long, and I recall that the largest ever found was a 29 meter female.

However, we now know about Seismosaurus. Seismosaurus averaged from 39 to 52 meters long, yet you still always see the dogmatic assertion that the Blue Whale is the largest creature ever. Now obviously, a respectable amount of the Seismosaurus’s length is comprised of the iconic neck and tail - maybe even half of it. But they still have mass, so even if you divide a 52 meter dinosaur’s length in half to 26 meters, with some mathematical additive factor for the neck and tail, wouldn’t you still end up with something larger than the record Blue Whale (let alone the average)?

Question the Second
Does anyone seriously believe that Tyrannosaurus really had those puny little arms, utterly tiny and useless proportional to its body? I mean, come on, that’s not evolutionarily advantageous - it might not even be able to get back up if it fell. No other carnosaur, or dinosaur in general, had such a “feature.”

I am personally inclined to think that one of two things happened. Either a baby tyrannosaur’s arms got put on the body of an adult; or the arms of a prey animal or other miscellaneous dinosaur that was jumbled in with the tyrannosaur’s bone’s got put on the T-Rex’s body. In either case, I believe it is a serious mistake. (Isn’t there only one “complete” t-rex skeleton - “Sue” or somesuch?) Do I have any basis for thinking this?

Thanks for listening to the semi-rant and hopefully for responding. :slight_smile:

No; it is an incrtedibly absurd conclusion; paleontologists jumbled up the forearms (and only the forearms) in every single specimen, even the ones that were found in articulated configuration? Absurd.
What do you suppose the tyrannosaur actually used those forearms for? How about this: Nothing - if you do absolutely nothing with your forearms, how could they be too small to be of use (if they didn’t have a use).

As far as getting back up after a fall is concerned, I know the scale is different, but penguins, ostriches and chickens seem to manage it.

…and there are five or sex complete T. rex specimens that have been found so far (out of about 25 total individuals).


Answer the First: Depends entirely on how you define “large”. Some of the larger adult sauropods were certainly longer than an average blue whale. But they were not even close weight-wise. Indeed, they couldn’t be, since in the water you don’t need to support your massive weight. Sauropods had a lot of lattice-work in their bone structure in order to lighten the load, as it were. Probably the heaviest dinosaur was around 50 tonnes. Blue whales can weigh over twice that.

Answer the Second: You start from a false premise: that the arms were “useless”. They were used for whatever they could reach. Remember that these arms were around 3’ long, and well-muscled. The only thing that makes them unusual is their size relative to the body. In which terms, it makes a lot of sense. A tyrannosaur’s arsenal lay in his mouth and feet. He was already pretty dang big; having proportional arms would have made him rather front-heavy. They weren’t completely useless, but they weren’t the primary means of interacting with the environment, either. Birds get along just fine with keeping their wings at their side for much of the time and manipulating the environment with their beaks and feet - so why not a tyrannosaur?

And “Sue” was the most complete, but not the only specimen to have the small arms. There are about a dozen or so relatively complete skeletons, and all show the same thing with respect to the arms. If these arms actualy belonged to a juvenile, this, too, would be evident based on the osteology: juveniles tend to have more cartilaginous bone-ends.