The ludicrous sizes of world-record individuals
February 6, 2023
This recent news story tells of a cane toad found in Australia that weighs six pounds. Here’s the photo, because it’s too good not to include:
Kylee Gray, a ranger with the Queensland Department of Environment and Science, holds a giant cane toad, Thursday, Jan. 12, 2023, near Airlie Beach, Australia. “We believe it’s a female due to the size, and female cane toads do grow bigger than males. When we returned to base, she weighed in at 2.7kg, (5.95 lbs) which could be a new record”, said Gray. (Queensland Department of Environment and Science via AP)
I am no cane-toad expert, so I am only going on what this news report had to say, but apparently the average weight of a cane toad is about one pound. So this new world-record individual masses six times as much as a typical adult.
Mature male saltwater crocodiles Crocodylus porosus are typically about 4.5 m long, but the world-record verified skull length is 76 cm long indicating a total length of about 7 m. Having a length 1.56 times that of a typical individual, this beast would have massed 1.56^3 = 3.75 times as much.
There may be less variance in mammal sizes. The world-record elephant Satao massed about 11 tonnes. That’s about double the typical adult African elephant mass, which is various reported as 5 or 6 tonnes.
Now think about sauropod sizes. We have a bunch of big Diplodocus specimens all measuring on the order of 25 m in length, and massing perhaps 15 tonnes. If world-record individuals compared to these as world-record elephants do, there would have been Diplodocus individuals of twice that mass (30 tonnes); if they compared as crocs do, we should expect giant specimens massing 3.75 times as much (56 tonnes); and if they compared as cane toads do, then the factor of 6 would give us giant Diplodocus individuals massing 90 tonnes.
All of this is speculative of course — wildly so — because we have such tiny samples of Diplodocus compared with the three extant species discussed above. It’s not remotely surprising that the ten or so specimens we have don’t include a freak like this. But there’s a good chance they were out there.
Oh, and for Brachiosaurus, of which known individuals massed perhaps 30 tonnes, it’s not unreasonable to imagine giant individuals massing 60, 112 or gulp! 180 tonnes. Yes, the imagination balks at the idea of a 180-tonne land animal: but that alone is not reason enough to discount the possibility.
Sauropod Vertebra Picture of the Week 
February 6, 2023 at 9:26 am
No, it is not unreasoneble at all to speculate that much larger individuals existed. More than a decade ago I have discovered a pair of massive EK hadrosaur footprints, measuring roughly 130-140 cm in length/width.
February 6, 2023 at 9:27 am
That’s really interesting, Berislav! A few questions: 1, did you write them up and/or photograph them? 2, how confident are you that they’re not undertracks? 3, how long are typical mature hadrosaur tracks?
February 6, 2023 at 10:03 am
Good to see a favorite topic come up again.
There are, what, I guess about 300 sauropod speices. With that many, a few sauropod species are possibly known only from a single individual, but that individual, unknown to us, happens to be in the top 1% of size. : )
1% isn’t necessarily “world record”, but probably it is much larger than average. (This is one common reason given for “well, we don’t really know which dinosaur was the biggest.”)
This reminds of a paper I read which was about highly variable growth rates found by doing osteology on a large number of Coelophysis individuals that had died in a single event. If sauropods grew that way, a sauropod that got an unusually large number of lucky (well-fed) years during childhood could end up super-huge. Conversely, one that suffered a near-starvation childhood would unusually small.
February 6, 2023 at 11:23 am
There is so much we don’t know. Does the existence of supersized individuals of smaller species mean that similar supersized sauropods existed? Or as sauropods may be already bumping up against a ceiling of maximum possible size, maybe they simply had less variance of adult body size?
February 6, 2023 at 11:33 am
It is certainly not impossible that the tiny samples we have of sauropods already contain all the size variation. But I don’t think that can be the null hypothesis, for several reasons.
Most importantly, those tiny sample sizes. Most sauropods species are known from one specimen, and very few if any from more than a dozen. Off the top of my head, I can’t think of one single species where there the number of credibly referred individuals runs into double figures. If we plucked ten individuals of any extant species at random, the chances of having one anywhere near the top end of the size range would be minuscule.
Second, there are tantalizing hints — such as the cervical vertebra BYU 9024, referred to Supersaurus but morphologically indistinguishable from Barosaurus — of crazy-big individuals of species otherwise known from much smaller specimens.
As for “bumping up against a ceiling of maximum possible size” — I’m old enough to remember when the six-meter wingspan of Pteranodon was the biggest attainable by a flying animal. The more I work on palaeo, the more sceptical I become of such ceilings.
But this is a good and important reminder that I really need to get on and write Why Elephants Are So Small.
February 6, 2023 at 1:22 pm
Here’s a link to an osteohistological study on Massospondylus, showing highly plastic growth:
Chapelle KEJ, Botha J, Choiniere JN. 2021
Extreme growth plasticity in the early branching sauropodomorph Massospondylus carinatus.
Biol. Lett. 17: 20200843.
https://doi.org/10.1098/rsbl.2020.0843
and here’s the Coelophysis study I mentioned earlier:
Barta, D.E., Griffin, C.T. & Norell, M.A.
Osteohistology of a Triassic dinosaur population reveals highly variable growth trajectories typified early dinosaur ontogeny.
Sci Rep 12, 17321 (2022).
https://doi.org/10.1038/s41598-022-22216-x
If these two studies apply to sauropods, they presumably have important implications for considerations of extremely large individuals, as well as extremely small individuals, and size distribution more generally. It might mean Mike’s saltwater crocodile analogue is more likely than his African elephant analogue.
February 6, 2023 at 1:25 pm
Idiotically, although I was aware of both these studies, I had not made the very obvious connection to this blog-post. Thanks, llewelly!
February 6, 2023 at 9:45 pm
You’re welcome.
I also think those papers may have implications for the long search for sexual dimetrism (size dimorphism) in dinosaurs; it seems to me this highly plastic growth would make dimetrism much harder to find (and perhaps less likely to be present, though I seem to recall most (all?) extant crocodilians do show sexual dimetrism ). But that’s a different topic.
February 7, 2023 at 1:18 am
I think that a size ceiling is a legitimate concern. After all, there is surely some body size beyond which even a sauropod with all of its tricks would begin to face significant challenges. If the sauropod species that reached the largest average body sizes weren’t approaching that level already, why didn’t they?
The notion of a size ceiling could possibly be tested by a study along the lines of “does the relative size distribution (using some measurable proxy for body size) differ between blue whales and other rorquals?”
One has to wonder how many of the poorly known super-giant sauropods (e.g. Argentinosaurus, Puertasaurus) are just known from individuals in an upper percentile of their population’s size range. At least we can probably rule it out for Patagotitan, as there are multiple individuals all around the same body size.
February 7, 2023 at 5:57 am
Just popping in to remind everyone of this post and its comment thread, where questions of max size got discussed:
https://svpow.com/2018/01/12/what-allowed-sauropods-to-get-big-and-what-kept-them-from-getting-any-bigger/
One limit definitely hit giant sauropods harder than any other dinosaurian clade: the biggest individuals were harder to bury. Increasingly, I wonder if the supposed upper limit of sauropod size is really just the limit of what can be buried — and therefore fossilized — in terrestrial environments.
February 8, 2023 at 2:02 am
Interestingly enough that maximum size living elephant may be less than the average size male specimen of several extinct elephants such as Palaeoloxodon namadicus; P. antiquus and Mammathus trogontherii.
It’s certainly a possibility, there was a paper recently on Neanderthals hunting P. antiquus at Neumawrk Nord in Germany and a couple of their older male specimens were estimated to be in the 13 tonne size class.
And even there the sample size isn’t enormous.
And male elephants more or less keep growing their whole life.
February 8, 2023 at 2:06 am
That is interesting. But I think it’s a different interesting thing from the one I was interested in here, which is to do with intraspecific size variation.
I didn’t know that elephants keep growing through life. Do you have a reference for that?
February 9, 2023 at 2:30 am
There’s a relatively recent paper here on African Elephants: https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2656.13035
For Asian elephants a paper here: https://pubmed.ncbi.nlm.nih.gov/26464339/
suggested their height growth ceases but the mails continue to gain weight until they are older than fifty.
February 9, 2023 at 2:45 am
Also this paper here: https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=d7ed311096687453f149dd0f04c6394d73ac5147
Given that females in oestrus give out subsonic calls to attract males and these can propagate both through the air and through the ground where other elephants can detect them through their feet; it raises interesting questions about how elephants on isolated offshore islands become dwarfed when there is such strong selection for males to become lager.
Perhaps waves crashing on beaches interfere with the propagation and detection of these calls on the mainland; and after females become dwarfed their calls become higher pitched and are no longer recognized by males of the original mainland species.
February 9, 2023 at 8:10 am
While this is a very interesting topic of course, I think we should take “net variance” into account. The lower variance spotted in elephants may have nothing to do with their physiology or phylogeny, but simply with their absolute size: variance increases along with the mean mass, but the mass distribution curve gets proportionally narrower. This can be tested with extant animals, even though all of the bigger ones are mammals, which might skew the results.
But assuming physiology has a significant effect on mass variances, should sauropods be expected to vary like mammals and birds, or more akin to reptiles? I think the former is more likely.
February 9, 2023 at 4:10 pm
the blog Joe’s Thoughts / Cetology Hub has some interesting articles of relevance to this thread. One is about extremely large blue whales, and the difficulties involved in estimated their tonnage:
https://callmejoe3.wordpress.com/2022/05/25/a-world-without-the-blue-whale-battle-for-the-throne-of-the-largest-animal-in-earths/
On re-reading this article (I’ve linked it before, in past threads; its rather a favorite), the enormously greater size of the females stood out. It’s probably well-known to most people, but for large social mammals, it’s unusual, and I suspect that if whales were known only from fossils, probably it wouldn’t be guessed. The specific reasons don’t have much to do with sauropods, but it’s a reminder that even reliable rules based on well-known relatives can have surprising exceptions.
February 9, 2023 at 4:12 pm
Oops, I posted the wrong link; I mean to put this link in my previous comment:
https://callmejoe3.wordpress.com/2021/10/03/the-blue-whale-putting-the-largest-animal-under-the-microscope/
February 9, 2023 at 4:13 pm
the second is about comparisons between the largest whales, and other exceptionally large creatures of the fossil record, including, but not limited to, sauropods:
https://callmejoe3.wordpress.com/2022/05/25/a-world-without-the-blue-whale-battle-for-the-throne-of-the-largest-animal-in-earths/
This is the link I mistakenly posted in the wrong comment, above. : )
February 9, 2023 at 4:13 pm
the third is about other species of whales:
https://callmejoe3.wordpress.com/2021/01/30/measurements-and-calculations-for-masses-of-large-whale-species-how-big-are-the-biggest-whales/
The most interesting part of this last article is how feeding habits and ecology of the various large whales interact with their size limits.