How big would an adult Dreadnoughtus be?

[jhg]

It's something I wondered myself since I heard the type specimen is not fully grown. What do you people think?

[Deleted]

We have literally nothing to go off regarding it's hypothetical adult size.

[jhg]

No one tried to measure its age? Unbelievable.

[theropod]

How’s that unbelievable? The majority of dinosaur specimens have never had their ages determined, even though it would be interesting to know them in every single one of them.
Plus, even if you cut open its bones and count its LAGs, that is not going to tell you how much bigger it would have grown. Matter of fact it is not easy to even determine the age accurately, especially if you have but a single specimen, since you generally need to retrocalculate some LAGs that have been resorbed by the medullary cavity, and others that have been obscured by remodeling. That's why age estimate tend to have significant Error bars. So determining Dreadnoughtus’ age is neither easy to do reliably, nor would it provide an answer to your question. And as broly already expressed, I also don't think there Even is a scientific answer.

@broly
On a related issue, regarding our recent discussion about skeletal maturity in tyrannosaurs, here’s a helpful passage from Horner & Padian that I had previously overlooked or forgotten about:

According to these estimates, a virtually fully grown T.
rex would have been between 15 and 18 years old. (How-
ever, as the femur of MOR 1152 shows, growth can drop
more precipitously than an incremental estimate suggests.)
We have not found in any sectioned T. rex tibia or femur
evidence of an outer acellular, nearly avascular layer similar
to the external fundamental system (EFS) (Cormack
1957), that indicates effective cessation of growth. (An
EFS has been identified in the ornithischian dinosaur
Maiasaura (Horner et al. 2000).) The absence of an EFS in
preserved specimens of T. rex could suggest that none of
the animals had stopped growing, although growth was
greatly slowing. Without an EFS, the near cessation of
growth seems the most practical indicator of full size.

Obviously an EFS has been identified by Erickson et al. in the same year in FMNH PR 2081, which was not studied by Horner & Padian, but the results seem to match up. "Skeletal maturity" in the sense of being "virtually fully grown" actually seems to fall together with the estimated age at reproductive maturity quite nicely (if I recall it correctly, you were right about your use of the term). However the state of skeletal maturity we see in Sue definitely goes well beyond that seen in other specimens.
ref: Horner, John R.; Padian, Kevin (2004): Age and growth dynamics of Tyrannosaurus rex. Proceedings of the Royal Society B Vol. 271 (1551) pp. 1875-1880.