An excerpt from google.books of Greg Paul next Princeton field guide book about the Mesozoic marine reptiles, out in october.
It appears he's downsizing quite a bit the largest ichthyosaurs. Other parts of the book are available on g.books.
Looking at my previous post, it looks like Max Hawthorne is not gonna appreciate Greg Paul's book.
I don't know Greg Paul, I assume he is a mosasaur, pliosaur, and/or ichthyosaur expert? Is he very credible and respected? I will say that his speculations about Megalodon seems to be quite inaccurate and not supported by most modern research, but if he's not a shark expert, I suppose that could be overlooked. What is his specialty and what is his resume as to published papers?
Does he make any predictions about the hypothetical enormous ichthyosaurs that are hanging out there as potentially the largest macro predators?
I’m late to the party, but since I am a dinosaur person and from a working group full of marine reptile people (even if I personally don’t work on them), and since I have read the book in question, here are my two cents in the form of a little "review" of sorts. Also switched threads, as this one seems more appropriate here.
Greg Paul is perhaps the most famous paleoartist in the world, and for good reason.
He was among the main artistic drivers behind the "Dinosaur Renaissance" back in the 80s, and authored some very influential works, such as "predatory dinosaurs of the world", which not only had a major and lasting impact on paleoart up to the present day (the classic white skeletal on black silhouette is basically his influence), but also illustrated some (for the time) revolutionary and sometimes downright prophetic hypotheses. E.g. Paul drew dromaeosaurs with advanced pennaceous feathers, a decade before the first non-avian theropods with any type of filamentous integument were discovered. Paul literally portrayed dromaeosaurs more accurately back in 86 than Walking with dinosaurs did in 1999, or Planet Dinosaur in 2011, or the most recent Jurassic World movie in 2022.
However, as others have pointed out, Paul is indeed primarily a dinosaur guy, and also primarily a paleoartist, not so much a research scientist. And this unfortunately shows sometimes, especially with some of the the papers he has published. Some I think are quite good (one also has to consider them in the context of the time they were written in, of course, since Paul’s career spans many decades by now), but others not so much (which is not to say that they are worthless either, but there is largely an agreement in the scientific community that at least some of his work isn’t very methodologically sound, and the resulting hypotheses at the very least quite idiosyncratic. Which is also why in his princeton field guides (which are of course not peer reviewed, nor exceedingly technical, and where he can thus freely present his own hypotheses without too much scrutiny) there are quite a few real issues.
Generally I would consider his field guide to dinosaurs to be a fairly good book (and certainly the best of the bunch) for the interested amateur, aspiring paleoartist or just generally the average online paleo nerd, at least as long as one has a little bit of experience and doesn’t just blindly follow whatever Paul writes when it comes to the science.
There are still some things in there that should be taken with more than a single grain of salt, e.g. his general propensity for shrinkwrapping his skeletals badly, or his sometimes weird taxonomy, such as splitting of
T. rex into several species (while, ironically, at the same time lumping other tyrannosaurines into
Tyrannosaurus on the genus level). But also for example his
Tyrannosaurus skeletals, which in some regards are just plain wrong when compared to actual fossils. For example, when scaled to the femoral and skull dimensions of Sue (which is 12.3 or 12.4 m long, we know that with a high degree of confidence because its vertebral collumn is essentially complete) his skeletal (for the "T. imperator", for which sue is his designated holotype) in an animal well under 11 m long. These are the skeletals from the latest edition of his princeton field guide to dinosaurs, and which he also published elsewhere in recent years, so I assume this is not some old work of his that he has since improved with better techniques, but something he genuinely still thinks is correct.
On the plus side, a big positive I have to note here is that compared to other books with which it would be fair to compare the princeton field guides (namely: popular scientific books aimed at laypeople, not the technical literature), Paul’s work is obviously far superior. For example, even if not all his skeletals are always the most accurate for the respective animal (which would be tough job considering the sheer number that he has done), he presents reconstructions of animals that showcase and are based on real anatomy and that he has carefully prepared himself over decades, where most popular science books would just license whatever more or (usually) less decent paleoart without any regard for accuracy.
Paul also provides mostly sound, detailed and standardized information along with all his reconstructions, even if he sometimes ventures into speculation and presents it as fact (or at least fails to explain that they are speculations), such as when listing hypothesized predator-prey-relationships and lifestyles. He presents stratigraphic information, anatomical characteristics, and size estimates that are based on the actual material (even if not always completely accurate), crucially also including volumetric mass estimates (that are usually fairly accurate at least to his skeletals, as far as the ones that I have checked go). I find the latter point especially impressive considering that as of my knowledge, Paul must be pretty much the last person on earth who still does his skeletals in analogue form, with pen on paper, and measures the volume of the animals using physical scale models rather than digital ones or mathematical volume estimation.
So much for the general points about Greg Paul as an author and a scientist. I’ve linked a short list of some technical papers or chapters of his below, including some of the more controversial one
Now,
regarding the Princeton Field Guide to Mesozoic Sea Reptiles, it pains me to say it doesn’t really live up to the scientific or artistic standards he set with his Field Guide to Dinosaurs (or his earlier work). Granted, it’s still better than your typical popular science book, but that’s about it, and that’s more down to the abysmal quality of most popular science books than the Field Guide being particularly great.
As mentioned, Paul is a dinosaur guy, and it really shows with his work on Sea Reptiles. I have no doubt that he has still spent quite a lot of work on this book, but it is nowhere near the levels of his dinosaur field guide. It starts with the skeletals, which compared to the ones of dinosaurs are often so much less detailed that they appear almost unfinished (sometimes I think they literally ARE unfinished). Take his head of
Monquirasaurus, for example:
Compared to what he did for the dinosaurs, this is just sloppy work. It’s not just that it is visually unappealing, that’s not really the issue here. It is absolutely possible for a visually unappealing illustration to still be scientifically valuable (or the reverse, of course). It’s that this severe lack of detail could indicate that perhaps a similarly limited attention to detail was paid in restoring the anatomy that is actually shown, which in turn could impact the accuracy.
I am also fairly confident I can spot some rather big anatomical issues with some of the skeletons in that book. Take his
Cryptoclidus for instance:
This is just wrongly proportioned. I spent a not insignificant part of the last 7 years literally sitting below a 90% complete, original
Cryptoclidus skeleton, and
Cryptoclidus does not look like that. The neck is far too long, the flippers far too short, for starters. Not to mention that for some reason, he has two completely different
Cryptoclidus eurymerus skeletals in his book, just one page apart, with no explanation. The other one isn’t a very good
Cryptoclidus either (though better than the first), which throws up the question if he just accidentally left a skeletal he didn’t mean to put there in, or maybe mislabelled one of them.
In any case, that generally fits my observation of him having worked far less carefully when preparing the field guide to sea reptiles as compared to the one to dinosaurs.
There is also some really whacky ichthyosaur taxonomy in that paper (sometimes he just seems to plain invent new supposed clades, such as the "Megamarinasaurids", which he basically came up with for a single species,
"S". sikanniensis), directly contradicting published taxonomies and phylogenies published by people who actually specialize in ichthyosaurs (even though I acknowledge that ichthyosaur phylogeny is a bit contentious). Importantly, and unlike in the Field Guide to Dinosaurs, much of his taxonomy here (and the phylogeny it implies) doesn’t seem to agree with any published phylogenetic work, nor does he seem to give much justification for it of his own. This is not how we do taxonomy nowadays. Just placing taxa in groups based on overall similarity, and personal guesswork may have been okay in the early 80s, before cladistic methodology became established, but nowadays we use phylogenetic analysis if we want to find out about evolutionary relationships. Phylogenetic analysis isn’t infallible, but it is one heck of a lot better than any author just reordering his taxonomy based on subjective guesses.
All of that generally makes me sceptical about placing his work in that book on the same level as that found in peer-reviewed literature, or at least done by people who provide detailed workup and explanations on the specific questions and taxa they are working on. If Greg Paul published a paper or a blog entry explaining, in detail, how he estimates the size of taxon X, and that explanation appears methodologically sound, then I have no issue at all with it, but that’s not really within the scope of what he does in the princeton field guide.
This is what he writes about gigantic ichthyosaurs:
I must say that this is a case where I see his taxonomical point regarding the genus-taxonomy, because other scientists also haven’t been able to figure out what genus this thing is, so it would arguably be best to just put it in its own genus to begin with (ironically this is the exact opposite philosophy of what Paul has when it comes to dinosaurs, where he just loves lumping multiple species, often separated by vast stretches of time and/or space, into one genus). But I absolutely do not get his point about the "megamarinasaurids", which, at any rate, would be useless as long as they include only one genus. As for his claims about ichthyosaur sizes being overestimated, I don’t find them implausible in principle, but he utterly fails to substantiate them.
There is also this passage earlier in the book (before the systematic part):
Also accompanied by this illustration of "S".
sikanniensis in the scale chart:
Here he again just makes these claims, but doesn’t really substantiate them. And to be honest, based on the skeletal diagram (which is another one of those that I would say look a bit sloppy compared to his work on dinosaurs), I remain unconvinced.
It is honestly hard to say if S.
sikanniensis was exactly 21, or 22, or 20, or 19 m long, because the skeleton is not complette. But what that doesn’t really change much at all is the overall size of the skeleton, for example the intergirdle distance can be reliably estimated at at least 8 m (because that much is preserved). Here I remain very doubtful (based on my own volumetric estimates based on the specimen and the essentially complete material of
Besanosaurus and
Guizhouichthyosaurus) about estimates for this specimen that are below 20 tons.
Whether the length might have been overestimated (his claim of a "misreading" is plain wrong, as Nicholls and Manabe explicitly state the estimated length at 21 m, the same figure they get cited for) seems to be almost a bit of a moot point. Yes, the specimen is incomplete as far as length is concerned. But it does have a reasonably well-preserved ribcage that gives a good impression of its volume, so the effect of the unknown tail and snout lengths on overall size isn’t all that big. There’s a large chunk of the vertebral collumn missing between the tail fin and the thorax. So depending on how long we restore the tail, and the snout tip, we could get very different lengths for the specimen. However Paul’s particular restoration is very odd, and does seem to conflict with the preserved fossil. He makes the tail (that is not preserved) oddly short, while at the same time making the snout oddly long. In his drawing he indicates this as if the snout tip was preserved…which it actually isn’t, it seems as though he has just made that part up. I don’t know what is going on here, but I don’t think this is a very good reconstruction at all, even within the bounds of uncertainty dictated by the incomplete specimen. And quite clearly, with an intergirdle distance of likely around 8 m, and a skull and neck likely to protrude in front of that at least another 4 m, and the entire tail behind that, a length of 20 m or more seems very reasonable. It’s just that Paul seems to have gone out of his way to portray the postcrania shorter than they are listed as in the description paper (longest rib 1.6 m instead of 1.9, intergirdle distance 5.5 m instead of 7-8m etc.). This together with the seemingly fabricated skull material doesn’t make me very confident in this reconstruction at all.
I would however certainly agree with Paul that some of the mass estimates that have been circulating for giant ichthyosaurs (just like some of the mass estimates that used to circulate for giant pliosaurs), have little basis in fact. For example, while I am not sure about the length estimate, I do think that Sander et al.’s regression-based mass estimate for the jim 2 specimen
Cymbospondylus-no-clue-why-paul-thinks-he-knows-better-than-the-people-who-examined-the-material-first-hand
youngorum at around 45 t is most likely a massive overestimate (whether the length estimate is too, I am uncertain). That’s because it bases on a fairly sketchy length-mass regression for all triassic ichthyosaurs (i.e. not taking into account differences in body shape between e.g. the likes of
Cymbospondylus and
Shonisaurus) that also includes very unlikely figures, such as the over 80 tons for S.
sikanniensis at 21 m (that Paul rightly criticizes), over 20t for a 13.5 m
Shonisaurus, and 1 t for a 5 m
Guizhouichthyosaurus. I get roughly half the mass estimates for these taxa at these sizes using volumetric models.
So that’s a point where I am generally on his side, but I think he’s gone too far overboard in the other direction. I am fairly confident
S.
sikanniensis, whether it be 19 or 21 m long, is an animal well in excess of 20 tons. I also think some shorter, but more robust ichthyosaurs (e.g.
Shonisaurus popularis, the giant temnodontosaurs from the Lower Jurassic, as well as
Himalayasaurus) may very well have achieved similar masses of 20-30t too (for both of them there are volumetric mass estimates that suggest these, although admittedly they are fairly speculative). These are the specimens of giant but not record-breaking ichthyosaurs that have been known for a long time. Then there are the extremely fragmentary, but extremely large rhaetian ichthyosaurs from the UK, France and Switzerland (and possibly New Zealand if Hector’s giant vertebra was real). These are of course fragmentary, but no more fragmentary than
Otodus megalodon, for which everyone, myself included, is very happy to extrapolate giant size figures from a few teeth, so I think in principle it is valid to try and make size estimates.
So far, direct comparison seems to indicate that the lilstock specimen is significantly larger than
S. sikanniensis, and some of the Aust cliff specimens were significantly larger still. Specifics of the size will of course depend heavily on the analogue we scale from, and the body shape we reconstruct. I have seen some rather extreme extrapolations from one of the coauthors of the description paper on twitter, that seemed to be based on Motani’s old volumetric estimate for
Stenopterygius (which I think is a sound estimate, but only for
Stenopterygius, not for totally differently proportioned shastasaurids):
These I think are quite clearly implausible, as they imply an animal as robust as a right whale, or more so, which is not congruent with even the body shape of Shonisaurus, let alone
S. sikanniensis that is a bit more slender than a rorqual based on its rib lengths.
Based on volumetric estimates I did for
S. sikanniensis (21 m, ~35 t, model based on the holotype and on
Guizouichthyosaurus) and
Besanosaurus (5 m, ~0.5 t), the two taxa Lomax et al themselves used for their length estimates, my estimates for the Lilstock Ichthyosaur range from 40-65 t, at a length of between 21 and 26 m (I posted a size comparison illustrating the estimates based on
Besanosaurus on the size scale thread. The Aust Cliff "bone shafts" are up to 30-50% larger by diameter according to Lomax et al., so as you can see that implies a vast possible size range based on these estimates, basically anything from less than 90 to nearly 220 tons could be justified. Which is the kind of error margin we get when extrapolating such incomplete material (the ranges for isolated megalodon teeth are similarly vast). And of course there are more ichthyosaurs that should be considered for comparisons, I would for example be interested what size figures one might get when scaling from more robust, but shorter-bodied and longer-skulled
Shonisaurus popularis. Depending on what we get, including more taxa could help narrow down the likely size range, or further widen it…
------some selected Greg Paul publications:
Paul, G.S. 1988. The brachiosaur giants of the Morrison and Tendaguru with a description of a new subgenus, Giraffatitan, and a comparison of the world’s largest dinosaurs. Hunteria 2 (3): 1–14.
Paul, G.S. 1994. Dinosaur reproduction in the fast lane: implications for size, success, and extinction. In: Carpenter, Kenneth, Hirsch, Karl F., and Horner, John R. (eds.), Dinosaur Eggs and Babies, 244–255. Cambridge University Press, Cambridge, New York, Melbourne.
Paul, G.S. 2012. Some notes on the diverse brachiosaurid sauropods of the Late Jurassic of North America, Europe and Africa. Figshare Available at: https://figshare. com/articles/Some_notes_on_ the_diverse_brachiosaurid_sauropods_of_the_Late_Jurassic_of_ North_America, _Europe_and_Africa/92543.
Paul, G.S., Larson, P. and Carpenter, K. 2008. The extreme lifestyles and habits of the gigantic tyrannosaurid superpredators of the Late Cretaceous of North America and Asia. Tyrannosaurus rex: the tyrant king. Indiana University Press, Bloomington, Indiana: 307–353.
Paul, G.S., Persons, W.S. and Van Raalte, J. 2022. The Tyrant Lizard King, Queen and Emperor: Multiple Lines of Morphological and Stratigraphic Evidence Support Subtle Evolution and Probable Speciation Within the North American Genus Tyrannosaurus. Evolutionary Biology 49 (2): 156–179.
Screenshots above are, of course, from Paul, G.S. 2022. The Princeton Field Guide to Mesozoic Sea Reptiles. Princeton University Press. I think these should quite unambigously fall under "Fair use" for purposes of critique and research in this context.
other refs:
Lomax, D.R., De la Salle, P., Massare, J.A. and Gallois, R. 2018. A giant Late Triassic ichthyosaur from the UK and a reinterpretation of the Aust Cliff ‘dinosaurian’ bones. PLOS ONE 13 (4): e0194742.
Nicholls, E.L. and Manabe, M. 2004. Giant ichthyosaurs of the Triassic—a new species of Shonisaurus from the Pardonet Formation (Norian: Late Triassic) of British Columbia. Journal of Vertebrate Paleontology 24 (4): 838–849.
Sander, P.M., Griebeler, E.M., Klein, N., Juarbe, J.V., Wintrich, T., Revell, L.J. and Schmitz, L. 2021. Early giant reveals faster evolution of large body size in ichthyosaurs than in cetaceans. Science 374 (6575): eabf5787.
Nicholls, E.L. and Manabe, M. 2004. Giant ichthyosaurs of the Triassic—a new species of Shonisaurus from the Pardonet Formation (Norian: Late Triassic) of British Columbia. Journal of Vertebrate Paleontology 24 (4): 838–849.
. I don't think it's silly to be clear on tonnes vs. tons. That's a 10% difference in weight. Not insignificant, especially if we are using comparisons to speculate the weight of another animal.
Me too.
