This just in from John Conway: {.alignnone .size-full .wp-image-17892 loading=“lazy” attachment-id=“17892” permalink=“http://svpow.com/2020/08/21/saltapotamus-meet-obesethocoelicaudia/obese-saltasaurus-saltapotamus/” orig-file=“https://svpow.files.wordpress.com/2020/08/obese-saltasaurus-saltapotamus.jpeg” orig-size=“2121,2121” comments-opened=“1”

“But wait, Matt”, I hear you thinking. “Every news agency in the world is tripping over themselves declaring Patagotitan the biggest dinosaur of all time. Why are you going in the other direction?” Because I’ve been through this a few times now.

I was a bit disappointed to hear David Attenborough on BBC Radio 4 this morning, while trailing a forthcoming documentary, telling the interviewing that you can determine the mass of an extinct animal by measuring the circumference of its femur.

I just gave an answer to this question on Quora, and it occurred to me that I ought to also give it a permanent home here.

If you’ve been reading around about Aquilops, you’ve probably seen it compared in size to a raven, a rabbit, or a cat. Where’d those comparisons come from? You’re about to find out.

In a comment on the last post, on the mass of Dreadnoughtus , Asier Larramendi wrote: So I did. The table of measurements in the supplementary material is admirably complete. For all of the available dorsal vertebrae except D9, which I suppose must have been too poorly preserved to measure the difference, Lacovara et al. list both the total centrum length and the centrum length minus the anterior condyle.

In the paper describing the new giant titanosaur Dreadnoughtus , Lacovara et al. (2014) use the limb bone allometry equation of Campione and Evans (2012) to derive a mass estimate for the holotype individual of 59.3 metric tons. This is presumably the “middle of the road” value spat out by the equation; the 95% confidence interval on either side probably goes from 40 to 80 metric tons or maybe even wider.

We’ve touched on this several times in various posts and comment threads, but it’s worth taking a moment to think in detail about the various published mass estimates for the single specimen MB.R.2181 (formerly known as HMN SII), the paralectotype of Giraffatitan brancai , which is the basis of the awesome mounted skeleton in Berlin.

As promised, some thoughts on the various new brachiosaur mass estimates in recent papers and blog-posts. Back in 2008, when I did the GDI of Giraffatitan and Brachiosaurus for my 2009 paper on those genera, I came out with estimates of 28688 and 23337 kg respectively. At the time I said to Matt that I was suspicious of those numbers because they seemed too low.

This post pulls together information on basic parameters of tubular bones from Currey & Alexander (1985), on ASP from Wedel (2005), and on calculating the densities of bones from Wedel (2009: Appendix). It’s all stuff we’ve covered at one point or another, I just wanted to have it all in one convenient place.