THE SCIENCE OF DINOSAURS – Yet more Tyrannosaurus Size Troubles, Will They Ever End?

Another BIG boo-boo in the size of the Tyrant Lizard, this time in the peer-reviewed literature

Did not expect to have to return to this subject so fast here on Substack (https://substack.com/home/post/p-189151706), but I suppose I should not be too surprised considering how overstating he size of Tyrannosaurus has become something of a paleo trend.

To repeat, I set the standards for meticulously restoring the dimensions of the profile-skeletals and using those to best estimate body masses starting in the 1980s. I have published in the peer-reviewed literature restorations of all the adult or close to it, reasonably complete Tyrannosaurus skeletons, as in Fig. 1 in https://royalsocietypublishing.org/rsos/article/13/2/252139/480521/Evidence-of-bird-like-foot-function-in, and in Princeton Field Guide to Predatory Dinosaurs with femur lengths in the pdf at the book PUP site, masses accompany both. You can take the measurements that have published for them and they all match up. Don’t agree? Fine, show where they are wrong. The masses are from work Larramendi and I are doing which includes both plasticine models and convex hulling which produce similar results, and our specific gravities from https://anatomypubs.onlinelibrary.wiley.com/doi/abs/10.1002/ar.24574.

So, in Royal Open Science https://doi.org/10.1098/rsos.252139 has just appeared a paper that has T. imperator Sue at 9.5 tonnes. Well that is a lot better than the 12+ in the Ji et al SVP abstract last year, but it is still way above the ~7.8 for Sue based on the accurately proportioned profile-skeletal. So where is the problem?

(Note that it is Sue specifically that is the problem, the Boeye et al. mass estimates for T. reginas USNM 555555 and Stan [now NHMAD 2020.00001 for ya all’s information – looks like it is popping up in the PR literature] are entirely reasonable. Not like the Ji et al. abstract which has 555555 up at 9.5 t.)

In Boeye et al. Fig. 10 they have a Tyrannosaurus profile-skeletal (by Witton) set in a meter grid. Excellent. For comparative purposes, to that at the same scale is my Sue here.

(Not for reproduction elsewhere)

Hmmm, looks like some significant differences here.

To wit, Sue dimensions from Brochu monograph are skull 1407 mm, last dorsal height 780, longest rib 1463, scap-coracoid 1310, ilium 1460, femur 1321. My Sue is a good match in all cases, as I am sure you shall all confirm via a metric ruler and calculator:)

The Boeye et al. dimensions are respectively 1595, 810, 1500, 1420, 1555, 1418.

Ergo, the latter is around about 1.07% too big for Sue. That inflates volume/mass by over 20 percent. Scale down to the actual dimensions to those of Sue with the Witton profile-skeletal femur at 1321 mm and mass would be under, well, 8 tonnes. So my estimate is the correct one for the specimen. It follows that my profile-skeletal is not any more “shrink-wrapped” than the other, they both show the predators in lean, belly not bulged with last kill, hunting condition (and the Witton restoration correctly shows the chest ribs angled backwards, keeping trunk volume properly low). So knock off the slander about my dinos being SW unless you can actually show otherwise.

If I have missed something here B. et al. are free to explain the error of my ways, and please do so to clear matters up.

And what are these 12 m plus length estimates for Sue? It is actually in the area of 11.5 m (38 ft). For one thing the vertebrae are too big in the long length values. And there are too many caudals, actual count was around ten less, hence tail tip too long and skinny.

The Fig. 9 Tyrannosaurus size did exist, maybe some fragmentary specimens are that size, and we will never find the biggest individuals. And the Boeye et al. ontogenetic series avoids the mistake of including small baso-eutyrannosaurs such as Jane (which I warned about last year in Mesozoic — was not cited on that:( – Teen Rex may be the best juv. specimen if that is ever described). But with Sue and Stan about the same size (the latter has the longer femur and no way it was 2 tonnes lighter, compare my Fig. 1C,E). With Sue and Stan about the same size, and with LACM 23845 so incomplete (I get a higher value of 2 t, but that is very iffy), there is not much of an ontogenetic series to base differential speed estimates on.

I have not checked the details, but the Boeye et al. speed estimate method appears very mass dependent. So knock 1.5 to 2 tonnes off of Sue. In any case such speed calculations have limited value at best. They are simulations of simulations, not observations of the real animals. If all deep diving marine mammals were extinct, would anyone correctly restore the high oxygen consumption mammals as able to dive thousands of feet? Not likely. Only way to know how fast flexed legged giant dinosaurs could actually run is via direct observation, which has various difficulties (or maybe very long stride trackways, but they are extremely rare). There is video of a running bull white rhino tripping and flipping head over tail through the air and getting up and running like nothing had happened, no computer simulations would accommodate that. Nor am I sure what the item about bird-like feet is about. This is true of al tridactyl digitigrade theropod dinosaurs starting back in the Triassic, none of which had the atypical two toed, semi-unguligrade toes apparently unique to ostriches. I have been pointing at that the long feet on flexible ankles of giant theropods allowed them to achieve suspended phase full runs the stump footed elephants cannot match (http://www.gspauldino.com/Nearlycolumnar.pdf).

The Royal Open Science Paper is an example of what I have and others have long been complaining about, the questionable science often published in high impact journals. Where is that all important rigorous peer-review? Had I – the person who established the modern standards for this sort of research -- reviewed this paper I would have caught the problems. As it is the authors and reviewers for some reason did not do the measurements they should have. It has been documented in the -- ironically enough -- peer-reviewed literature that prestige journals are actually lower in average scientific quality, and why (https://www.frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2018.00037/full; https://bjoern.brembs.net/2016/01/even-without-retractions-top-journals-publish-the-least-reliable-science). Here we are well into the 21^st century and there are still titanic problems in correctly estimating the size of extinct beasts (as per https://palaeo-electronica.org/content/current-in-press-articles/5431-trimming-down-perucetus), when the methods for doing it right were set nearly four decades ago. And anyone who gets it wrong should know I and Asier will get after them for it, so why get into the trouble? Just saying.

Concerning the 12+ tonne Sue, one hopes Ji et al. will have done the carefully measured lateral and dorsal view skeletal that solidly justifies such Jackie Gleason mass proportions. And directly compare it at the same scale as mine for comparative purposes to show why 7.8 t is much too low. Indeed, my skeletals have been published in the PRL, so they are available for modelers to use as is, or with suggested alternations if they are in accord with the data. Just ask.