The Chubut Monster is officially named!

Posted by Nima On Thursday, August 10, 2017 1 comments

Today the Chubut Monster, possibly the largest dinosaur known, has been published.

There are apparently six specimens from the same site. The largest of them may have exceeded 120 feet in length, and though the paper proposed a maximum mass of 82 tons, I suspect that when restored with the correct rib curvature and soft tissue levels, this animal may have exceeded 110 tons.


The AMNH mount, which is entirely made of fiberglass replicas, appears to be based on the holotype and a few similar-sized specimens. These are still smaller than the individual represented by the gigantic femur on the forklift pallets.


Patagotitan mayorum is build like something between Argentinosaurus and a lognkosaur, with traces of Malawisaurus-like features as well. Though the cladistic analysis in the paper is odd to say the least (taking Rinconsaurus and most other aeolosaurs out of Saltasauridae and making them sister-group to lognkosauria, and throwing Argentinosaurus into lognkosauria, while throwing Malawisaurus into a derived lithostrotian cluster!) it does make two very interesting points; not only is the new Chubut Monster Patagotitan related to Argentinosaurus, but Ruyangosaurus is classed as a titanosaur more derived than Andesaurus.



It seems ironic that the paper does not draw a closer relation between Patagotitan and Ruyangosaurus, because the morphology of their posterior dorsal vertebrae appears almost identical. The oddly leaf-shaped neural spines, the many shallow and thin laminae, and V-shaped prezygapophyses so recently having lost the hypantrum, are very similar to those of Patagotitan, which still retains a small hypantrum in a few of the mid-dorsals. The slender neural spines of the caudal vertebrae recall Mendozasaurus. The centra of the dorsals resemble Malawisaurus to some extent, and Argentinosaurus from certain angles. It's looking like Patagotitan occupies a node on the titanosaur family tree somewhat more derived than Argentinosaurus, a direct descendant of the fork in the road between the "Malawisaurs" (Malawisaurus and Savannasaurus) and more derived groups such as the true lognkosaurs.



The biggest specimen of Patagotitan is known from a femur that both has the unusual proximal curvature of that of Ruyangosaurus, and a size exceeding the (reconstructed) length of the Argentinosaurus femur.




A terrible skeletal of Patagotitan. In reality the neck and back would have been steeper, and the tail likely less kinked downward.


Well, I have to admit it.
It was tempting to draw large tyrannosaurs with a heavy coat of feathers. It proved VERY tempting. But I stuck to my guns and held out on it. Why? I wasn't convinced the evidence would favor it.

I had already seen pictures of skin impressions attributed to the neck and chest of T. rex, and they were scaly. But this wasn't published and therefore people were casting doubt on it (I wonder if they did the same when Yutyrannus photos showed feathers, before it was formally published and described?). Now some may ask what I have against feathered tyrannosaurids, since that is the new orthodoxy in much of paleo-art (just as lizard-like restorations were orthodoxy in the time of Knight and Burian). The answer is actually: nothing. But when talking about giant tyrannosaurids there was no actual evidence of feathered skin. Not only that, but being roughly 1.5 times the length of the still taxonomically controversial Yutyrannus, the largest T. rexes at 12 meters were over twice the mass, and in addition they were living in a time with warmer global temperatures and increased SO2 and volcanic activity.

I maintained for years that if T. rex had any feathers as an adult, they would probably be in very limited areas, for display. Something that big would not need them for insulation, and as a warm-blooded predator in the Maastrichtian epoch with rising global temperatures, it would likely overheat with a heavy coat of downy insulation feather, and obviously had no use for long-quilled flight feathers.

Now we have a paper just out confirming that big tyrannosaurids were probably scaly over the majority if not all of their body surface - and that feathers were lost relatively early in the evolution of true Tyrannosauridae.
rsbl.royalsocietypublishing.or…
And this isn't some fringe paper in a fake journal by creationists or BANDits. It's Royal Society, and Phil Currie, Bob Bakker, Darren Tanke and Pete Larson are all among the co-authors. You don't get more solid in credentials than that. I don't even think Jack Horner would take issue with their scaly conclusion, given his historically conservative approach to dinosaur biomechanics and metabolism.


Interestingly, not only are the skin impressions scaly, but the scales are tiny. Bead-like, almost. So most likely these are from a softer part of the body, possibly the undersides, but due to decomposition the skin may have become desiccated or detached, and rolled around to the dorsal portions of the body, which are apparently the positions in which the skin impressions were found.


Now I can imagine some people having nightmares over their entire post-dotcom idea of a poofy T. rex being overturned. So what does this really mean for the big picture of tyrannosaurs?

Does it suddenly mean they were cold-blooded overgrown alligators? NO. Warm-bloodedness is not dependent on feathers or fur, especially not at those sizes.
Does it mean that they were unrelated to birds and we need to rip up the theropod family tree? NO. The paper states that the tyrannosaur lineage lost their feathers, not that they never had them.
Does it mean that all the old pre-Bakker images of sluggish tail-dragging T. rexes were correct? NO and no. These certainly weren't the only unfeathered tyrannosaurs ever drawn or painted, and definitely not the most anatomically informed (Burian was even famous for not looking at fossils or estimating proportions). There's no reason to throw out 40 years of gathered evidence of warm-blooded, fast-growing bone texture in tyrannosaurs. Tyrannosaurs were still active, fast, warm-blooded hunters. They just weren't drowning in feathers at 40 feet long.
 
But this doesn't mean that I favor Jurassic Park's ugly monsters either. And simply favoring scaly T. rexes doesn't make you some obsessive JP fanboy. It simply means you listen to the evidence - several scaly impressions in 5 different tyrannosaur genera, and not one feathery impression from any of them. Interestingly, none of these impressions match the big, bulky crocodile-like scales and heavy wrinkles in the Jurassic Park T. rex. Yet I already see and hear some hurt naysayers claiming that everyone who questions the unproven notion of T. rex feathers is somehow a Jurassic Park fan with an agenda who hates feathers. It couldn't be further from the truth.

I was never a big fan of the Jurassic Park franchise, and even now the scale evidence doesn't support their big alligator-like scales or heavy baggy wrinkles on their T. rexes. What's more, the JP 'rexes had obvious errors in their facial appearance, including the lumpy 'gator-like orbital horns and huge triangular jugals, and the "cutout" sections of the lower jaw that they fit into... As if somehow having any overlap of the upper jaw around the lower was a sin to Spielberg, as if they had to close perfectly interlocked like a crocodile. We know that the scale impressions show much smaller and finer scales than anything in the JP franchise. My reasons for questioning the idea of giant 8-ton tyrannosaurs being feathered have nothing to do with a hollywood movie. And everything to do with (a) the evidence, and (b) the simple fact that they were giant 8-ton tyrannosaurs in a rapidly warming Hell Creek climate.

So they did have scales over several parts of the body, and the scales in the hip area indicate it's highly likely the torso was scaly as well. You just don't see scaly hips in any feathered creature, even flightless birds have feathers on the hips and tail (or what's left of it). Of course this doesn't change anything about dinosaurs that we know either had feathers or were likely to have them - like dromaeosaurids ("raptors"), ornithomimids, oviraptorids, caegnathids, etc. A scaly tyrannosaur doesn't negate these animals being feathered, nor does it have any effect on feathered specimens of controversial species sometimes labeled as basal tyrannosauroids, but which may not be (i.e. Yutyrannus).

In fact, the paper's argument is that tyrannosaurids evolved from small feathered ancestors, but likely later lost the feathers as they evolved into giant top-tier predators.



In that case, knowing that the scales were very small, and nothing like the baggly wrinkles and 'gator scutes in Jurassic Park, we can now ask: what is the most accurate T. rex image, based on these scale impressions? It would obviously have to be something post-70s, when Bakker and the Dinosaur Renaissance were gaining steam, and anatomical accuracy really began to matter.

You might say Greg Paul's version. And you'd have a point. Though many of the visible scales here look a good deal larger than the ones in the impressions, not all the scales are visible, and some patches on the underside look like a good place for much finer scales. If the rest of the body was covered in similar, if somewhat larger scales, you would likely have the smooth, tight, and only lightly wrinkled skin you get on Greg Paul dinosaurs.

T. rex pair by Greg Paul. 1988. Based on the AMNH specimen. Used for educational purposes only.

However, Brian Franczak's slightly less "vacsuit" version is another contender:

Brian Franczak's T. rex and Edmontosaurus. 1991. Used for educational purposes only.

There's not much surface detail in Franczak, aside from a few veins and light wrinkles. That's just the style. But overall the anatomy looks solid here and the skin smooth enough that those tiny scales in the impressions would be right at home. The legs are a bit more bulky here, but still not like in JP. The head looks oversized in the far left animal, but that's just a perspective trick for dramatic effect.

Another great rendition of accurate, fine-grained T. rex skin is in Larry Felder's painting of a juvenile 'rex, which was the cover image for the book In the Presence of Dinosaurs. You can almost feel this is a real live animal breathing next to you. The scales struck most people as too tiny, the skin too smooth and "cute" - but after seeing these skin impressions with some scales only a couple of millimeters wide, it's hard not to wonder if Felder had some kind of sixth sense for these things.

Larry Felder's young T. rex from the book cover. Not based on a particular specimen. Educational purposes only.


But if you were to ask me which painting of T. rex looks the most like the actual textures and scale shapes in the skin impressions, I'd have to give it to this long-forgotten gem:

T. rex by Dave Marrs. Apparently based on the Wankel/MOR specimen. Used for educational purposes only.

Now I don't know how many of you are familiar with Dave Marrs' work. He did a large number of paintings for the TV series PaleoWorld in the 90s, which is where I was first introduced to the art of Greg Paul, Brian Franczak, Mark Hallett, David Peters and many others (back then Peters was solidly popular as an artist, and followed the best cutting-edge science of the day, almost like a second Greg Paul - and there wasn't anything too unusual about his paleo-images at that time, even the pterosaurs). Marrs also did some unrelated images for a series of Jurassic Park trading cards, which were largely concept art for the movies.

Apparently Marrs got into legal hot water when he closely copied a number of images from Paul and Peters, robbing both to pay himself and not getting permission to copy copyrighted images. Some of these "re-skinned" copies were also featured in PaleoWorld, most notoriously his Estemmenosuchus, which was a ripoff of Peters' original. But, it must be emphasized, not everything Marrs did was a fraud. He also had many original paintings and no doubt he proved his skill as an artist.

Probably his best painting was the one above of a blue T. rex with relatively thin, basal lips and some VERY detailed scalework. The facial scales are a bit on the large side, but those on the underside of the neck are downright tiny. And this matches the look of the skin impressions almost perfectly. Now given, there are some flaws with the oversized teeth and the jaw proportions, but some of this is due to perspective distortion and stylistically it's a very good painting. And if the skin impressions are any clue, this is easily the most accurate skin in a T. rex painting. Too bad more isn't known about this image, it really does stick with you.

From a distance, some vintage "Dinosaur Renaissance" paintings, like Greg Paul's Daspletosaurus, even did away with extensive scale texturing on the majority of the skin altogether, leaving it to the viewer to imagine what those tiniest of scales looked like up close.

Daspletosaurus by Greg Paul. Based on holotype CMN 8506. Updated version with revised supinated hands. Used for educational purposes only.

Now in the future someone might find skin impressions in other parts of the body of a tyrannosaurid, that indicate the presence of feathers. But so far there are none, and 100% of the few rare skin imprints found of tyrannosaurs thus far, are scaly. The trend to put feathers on tyrannosaurs was always a speculative one, with no actual tyrannosaur evidence to back it up, the closest analogues used being only distantly related and much smaller theropods like Guanlong, Dilong, the maniraptora, and the possibly non-tyrannosauroid Yutyrannus, whose size has often been overestimated. The new paper shows that the five best-known tyrannosaurid genera were scaly over at least several parts of the body, and it's unusual to have feathers limited only to the torso or other regions lacking skin impressions. Even flightless birds today don't have naked hips or tails.

Which brings up an important thought - perhaps the scaly but nevertheless sleek and hot-blooded "Dinosaur Renaissance" T. rexes of the '80s and '90s are not so far off the mark after all. Aside from the pronated hand postures common to that era, they pretty much got it right.








We've seen different snouts, different beak shapes, different frill stud counts, different frill shapes, different squamosal shapes, and different horn shapes in the biggest and most mature specimens.

But guess what we haven't seen? Different details IN the horns.

This is the skull MOR 1122 - one of the two huge "boss-nosed" Torosaurus skulls, both of which are in Jack Horner's own Museum of the Rockies.


See anything odd about the brow horns? Anything sidesplitting that doesn't appear in any Triceratops?

Those deep chasms in the horns are real. Only the horn tips and the beak have been restored.

Lets look at some well-known Triceratops skulls:

Cast of T. prorsus holotype at the NHM, London


The "Kelsey" Triceratops - a very old individual of T. horridus.

the very mature TMP T. prorsus skull - no epoccipitals left here!



The "Homer" skull, another elderly T. horridus - seriously who picks these names?


couple of young T. prorsus skulls at Seckenberg museum

The Torrington skull - old individual, appears to be T. horridus, NOT the same skull as "T. eurycephalus".

Dakota dinosaur museum T. prorsus skull.

Another, younger T. prorsus - there is a slight groove that expands at the horn tip, but no huge chasm in the midshaft of the horn. Additionally, this short-faced skull is one of the LEAST Torosaurus-like out of all the Triceratops specimens known.


NONE of them have those deep chasms you find in Torosaurus.

So now we can see that not only do the horns of most Torosaurus skulls have a different shape than one would expect for a mature Triceratops, but even the anchoring surfaces of the bone cores that held the horn sheaths in place were different - namely that Torosaurus had deep clefts in the bone cores that the outer sheath would have hooked into - something completely absent in Triceratops.

Now not necessarily every Torosaurus would have had these natural gashes, but the ones we have complete or near-complete horns for, do show them. The odd thing is, the most mature Triceratops skulls don't have such gashes in the horns, not even smaller ones.






 

'Toroceratops' is BUSTED. Conclusively.

Posted by Nima On Tuesday, May 16, 2017 1 comments

Q: I have heard that the Jack Horner theory about Torosaurus being nothing more than old individuals of Triceratops is getting a lot of pushback. Paleo King, what are your views on the theory, and what does the evidence actually say?
 
A: They are arm-waving. Horner actually has a pattern of doing this, it isn't the first time. Remember the “obligate scavenger T. rex”? Every piece of evidence Bakker, Currie, Weishampel, etc. looked at, Horner basically ignored or dismissed or even denied – even things as basic as eye socket shape – just to preserve his precious theory. Later Horner confessed that he “never liked T. rex anyway” (he was always primarily a duckbill specialist, whose best work was with the Maiasaura nests) and never took the “100% scavenger idea” seriously, he simply went on TV and made these claims because he wanted to stir debate and knock T. rex down a few pegs. But making an argument you know is weak simply to stir debate, is the most unproductive sort of debate there is. Paleo-trolling before there were tumblr and buzzfeed.

You'd think his fans would have learned from that whole fiasco. Most of them don't even know it happened. Score? Hornerite groupies: 0. Horner: 1


As for the “Toroceratops” theory – although Horner (but moreso his former student John Scannella) actually published academic papers and piling up skulls on this new idea, unlike with the scevenging T. rex theory, the line of argument in the papers is hardly any stronger, and the piles of Triceratops and Torosaurus skulls he cites as proof, do not actually support his claims. The theory basically runs like this: Triceratops and Torosaurus are found in the same rock layers and general region, they look very similar, both have metaplastic bone in their frills indicating bone remodelling, hence “obviously” one must be a growth stage of the other. Except that there's no real conclusive proof for that argument. The fossil evidence in their papers is either circumstantial or not in support of their theory, and some of it is even heavily altered with plaster. The make conclusions about the skulls, which the skulls themselves actually contradict! Same can be said for much of their Pachy-stygi-dracorex theory, which makes a ton of assumptions based on casts, stress fractures, and artifacts of preservation rather than native features of the fossils, as well as for Fowler's "Haplo-Suuwa-Bronto-Diplodocus" faux-pas, where downright bizarre fictions like "weighted characters" and "selective parsimony" had to be invented to turn sauropods that are clearly NOT diplodocids into good little juvenile diplodocids (just ignore the fact that Haplocanthosaurus is also known from non-bifurcated adult neck remains too, right?).



Don't you get all bifurcated on me too now....

There's no way to prove that Torosaurus was simply an old adult Triceratops. There are some VERY irreconcilable differences and between the two, and some gaping holes and assumptions in their hypothesis - even if you use ontogeny to "rationalize away" some of the variation. How Jack Horner and his team can hope to bridge these holes in their theory, I honestly have no clue:

1. The changes required are too radical for an animal that is no longer juvenile and has no growing left to do in the postcrania. Such an extreme and late change in facial geometry is unknown in any ceratopsid.

2. Torosaurus is far rarer than Triceratops, too rare to simply be the same animal a few years older. 90% of Hell Creek's large herbivores are Triceratops, Torosaurus forms less than 1%. Some may argue that this is only because few herbivores survived to old age, or that older individuals were more vulnerable to be eaten rather than fossilized – but this is pure speculation, and reason # 4 forces us to discard this idea.

3. Torosaurus has many more epoccipitals than Triceratops - and not only that, their numbers are far more variable in Torosaurus (from 30 to 37), while Triceratops always has exactly 17 (except in elderly skulls where they are reabsorbed). Scannella at SVP claimed that "perhaps Triceratops split their epoccipitals in half to double the number" - something that I can only guess was tongue-in-cheek, since there is no specimen showing evidence for such "stud splits" in either Triceratops, Torosaurus, or any other ceratopsid, much less any dinosaur, period. It sounds even more ridiculous when you realize that Triceratops actually LOST frill studs as it aged, it didn't add new ones. Those near the bottom of the frill tended to disappear first, and in the most mature Triceratops skulls, all of them are gone. To add new frill studs would be a reversal of the entire Triceratops aging process.

4. Torosaurus has never been found in association with Triceratops. If they were simply aged Triceratops, they would realistically be found in the same herds/locations at least some of the time, especially if they were weaker than young adult Triceratops and needed the protection. This association has never been known to occur for Torosaurus. You just don't find them at the same dig sites as Triceratops.

5. Different head/body proportions, even discounting the frill. The Milwaukee specimen of Torosaurus [link] has larger skull (including jugals) than Triceratops, but much smaller postcrania. Doesn't make sense why an adult animal's individual bones would be smaller than those of a "juvenile". Of course Horner doesn't specify if his 30-footers are really juvenile Triceratops or middle-aged adults, he just claims Torosaurus are "old adults". Ok whatever.

6. Torosaurus is actually smaller than Triceratops. As in, the entire body except for the head, is smaller – every bone is smaller than in the most mature Triceratops. How can an “adult” of one species have a smaller body than the “young”, and even smaller limb bones, ribs, and vertebrae? (every postcranial element from Torosaurus indicates an animal 24 ft. long, not 30 ft. as in the most mature Triceratops skeletons! I know humans and some animals lose height as they age due to cartilage contraction, but shrink the femur, the ribs and the humerus? SERIOUSLY? These parts don't even have any metaplastic bone in Torosaurus, nor do they show any proof of bone reabsorption!)

7. Horner and Scannella have never done a histological age analysis on Torosaurus postcrania to actually prove that they are any older than the biggest accepted Triceratops specimens. This would be far easier than guessing age from the skulls, since as mentioned above, postcrania do not typically feature metaplastic bone or remodeling. Not that being older would actually prove that they're old Triceratops per se, but it would at least remove one huge logical impediment that stands in the way of Horner's theory being more accepted – on the other hand, a young age for these bones would nuke it.

8. Beak shape in complete skulls is radically different - Triceratops had a strongly hooked, recurved "eagle" beak, while Torosaurus has a much less curved "condor" beak that slopes downwards and forwards, the traditional Chasmosaurine beak design. The sloping “condor” beak is also present in Eotriceratops, which is otherwise far closer to Triceratops proportions than to Torosaurus – putting even more taxonomic space between them.

9. Nasal horn position (and snout/beak length ratio) differs between Torosaurus and triceratops. Torosaurus has shorter post-nasal-horn snout and a longer beak. No ceratopsian is known to radically change beak shape or beak/snout ratios when reaching maturity.

10. Even in very old Triceratops, Torosaurus-like features are extremely rare. The only Triceratops specimen that shows even remotely Torosaurus-like snout proportions and horns is the Torrington skull [link] , which is a very old adult with reabsorbed frill studs but NO fenestrae in the frill! This may be the most basal Triceratops morph, close to a fork with Torosaurus. Even so, the beak curvature is still not identical to Torosaurus.

11. There appears to be ontogenic variation within Torosaurus itself! [link] The Yale specimen, the MOR specimens, the Denver specimen and others all show a great deal of variation in epoccipital reabsorption and horn curvature - indicating that Torosaurus a unique creature that underwent ontogenic changes and growth stages of its own, and not merely a “final phase” of Triceratops.

12. There are other ceratopsids even closer to Triceratops (like Eotriceratops, Nedoceratops, and Ojoceratops) that don't fit comfortably in any part of Horner's ontogeny sequence. Nedoceratops is the real wild card, as Horner and Scannella claim it as proof of the Trikes aging into Toros - but while it has a few things in common with both, it fails dismally as a "midlife crisis" stage between the two, since it has a very odd mix of features that, taken together, make no sense in a Triceratops growth series. They are only found individually in Triceratops of completely contradictory age groups, and most of them are not found in Torosaurus at all. Nedoceratops has a very "perky" high horn angle completely inconsistent with the forward curvature of the horns themselves as well as the skull's advanced ontogeny, if one were following Horner's theory [link] to its logical conclusions. Its horns curve like an old Trike, but their bases are angled up and back like a baby Trike. It beak roughly follows Torosaurus (almost nothing else on its face does) and Eotriceratops, but is shorter than in either, and its frill is essentially a more compact version of Eotriceratops - far shorter and more compact than a Toro frill, yet obviously also older than many Toro frills, judging by its heavily reabsorbed epoccipitals. Its squamosals don't look like anything known in either Triceratops or Torosaurus. Horner and Scannella's nomination of this skull as an ontogenic “transition” from Triceratops-morphs to Torosaurus-morphs is laughable. There isn't a hint of Torosaurus in its short frill length, low epoccipital count, or steep horn angle, and especially not in the squamosal. There is also a second, larger skull that appears to be Nedoceratops - CMN 8862, which was once labeled "Triceratops albertensis". It has the same "perky" horns and the same short, upcurved, very un-Toro-like squamosal. Clearly this animal had a different ontogeny pattern as it grew than either Triceratops or Torosaurus. It likely branched off from the family tree sometime after Torosaurus and before Eotriceratops.

13. Fake plaster fillers are misleading. The beak of the YPM Torosaurus skull, as well as the horn tips and rear frill of some Torosaurus skulls and most of the Milwaukee specimen skull have been incorrectly reconstructed to look like Triceratops. Also the MOR skulls have a huge nasal boss in place of a horn, which is not consistent with anything seen in Triceratops, least of all the beak structure. It's actually a bit shocking how the most commonly pictured Torosaurus skulls have FAKE BEAKS and FAKE skull fullers in general that are modeled on Triceratops skulls, rather than more complete Torosaurus skulls - GetAwayTrike faithfully reproduces both the complete skulls and the fragmentary ones with fake Triceratops-mimic plaster fillers (recurved eagle beaks, short snouts, etc.), the differences are often extreme. Of course some of this error was probably due to lack of access to all the Torosaurus material, and earlier date of discovery/preparation with some specimens, but still... most of what you may THINK are correct Torosaurus orbital, snout, and beak features, are FAKE. Those that have a mostly complete beak, like ANSP 15192 and the far larger MOR 981, show a VERY different beak structure than in mature Triceratops.

14. The degree of cranial variation between Triceratops and Torosaurus is greater than that between many closely related modern bird, reptile, and mammal genera. Take antelopes as an example: ignoring the keratin horn sheaths, the actual skeletons and skulls that can fossilize are VERY hard to tell apart. There is hardly any cranial variation comparable to that between Triceratops and Torosaurus. Are we then to conclude that the Gemsbok is simply an immature Eland, or that the Springbok is an ontogenic stage of the Thompson's Gazelle? A better case could be made for using Horner's lumpery on these, than on Torosaurus, even though we clearly know these animals are not growth stages of each other. Impalas don't turn into Heartebeest, even though their bodies are basically the same design on different scales! There's a lot of diversity even in unhealthy human-damaged ecosystems. So even if the Maastrichtian faunas of the Rockies were doing badly in terms of diversity, it's doubtful that triceratops was the ONLY horned dinosaur there. The presence of Ojoceratops, Tatankaceratops, Eotriceratops, all of which are more Triceratops-like than Toro, further confirms this.

15. The raw morphometric data does not support lumping them. Farke, et. al. (2013) determined the changes required to "age" a Triceratops into a Torosaurus to be UNPRECEDENTED among ceratopsids, requiring addition of epoccipitals (frill studs), reversion of bone texture from adult to immature back to adult, and unusually late growth of holes in the frill. The Torosaurus specimens cluster together, separate from the Triceratops cluster on the morphometric plot.

16. Torosaurus has its own immature specimens. These, such as the ANSP skull, have a shorter and more upcurved frill that had yet to fully flatten out, and their beak shape, horn angle, and fenestrated frills are still clearly distinct from Triceratops of the same growth stage (or any growth stage for that matter). It's not so easy to claim that Torosaurus is the mature form of Triceratops, when it has its own juvenile specimens that are clearly NOT Triceratops. They even have high frill stud counts, just like the Torosaurus adults. Clearly these animals did not closely resemble Triceratops, even when less than half-grown.

17. Large parts of Trike's and Toro's ranges do not overlap. Juvenile Torosaurus were found in Big Bend National Park, Texas, which is conspicuously devoid of Triceratops material - though Ojoceratops is present in nearby New Mexico – a compact, short-faced and short-frilled animal, almost as different from Torosaurus as it is possible for a derived chasmosaurine to be. Ceratopsid faunas, it seems, were far more diverse than the plain one-genus badlands Horner would prefer them to be.

18. Many large Torosaurus are less mature than the most mature Triceratops. Most of the Torosaurus skulls, including the largest ones, actually appear to be ontogenically LESS mature than the largest Triceratops skulls. This is true both in terms of epoccipital reabsorption and the amount of metaplastic bone. The MOR skulls in particular are gigantic, but clearly immature, having young, well-defined epoccipitals/epipareitals and relatively small fenestrae, which may mark them out as a unique new species within Torosaurus itself.

19. Torosaurus horns typically look more like teenage Triceratops than mature ones. The most complete Torosaurus skulls all have relatively slender and typically straight horns, and some have a slight double curve - not the thick robust forward-curving horns of mature Triceratops. In fact the closest thing to a Torosaurus brow horn among most Triceratops is adolescents or young adults of Triceratops which have barely attained the double curve stage: [link] let alone the strong forward curve stage of mature Triceratops horridus and prorsus:[link] [link] In order to actually turn the most mature Trikes into Toros, you would have to actually reverse the changes in their horns - undo the mature forward curve, re-lengthen and re-straighten them and in some cases even re-add the double curve found in younger Trikes - all while the postcrania mysteriously shrink by 25%! What a completely unnatural and pointless waste of metabolic processes and resources. And it doesn't happen in ANY other ceratopsid known to man.

So did mature Triceratops just straighten out their horns a SECOND time and make them longer and slimmer after having already absorbed the tips and thickened the bases [link] , reversing much of the normal Triceratops aging process, all to become Torosaurus? I doubt it. There's no "Benjamin Buttonceratops" in Hell Creek, we're simply looking at two genera where the ontogeny changes worked differently.

20. Mature Triceratops specimens actually appear to be shortening the frill, not lengthening it. This goes along with the fact that they were reabsorbing and in some cases losing frill studs, not growing extra ones. The frills of many old Triceratops skulls are, if anything, receding. This is especially the case with T. prorsus, but it appears in some old T. horridus skulls as well. MOR 004 (prorsus), SMNH P1163.4 (prorsus), TCM 2001.93.1 (horridus), and several others, have the forward-curved horns and reabsorbed tips of old individuals, but the frill is moving in anything but a Torosaurus-like direction. If anything, it's proportionally shorter and more compact than in the less mature large Triceratops specimens with double-curved horns. Once again, just like with the horns and frill studs, lengthening the frill or growing new frill in these mature skulls would actually be a reversal of the normal Triceratops aging process up to that point. Some T. horridus individuals like UCMP 113697 do have a longer frill, but still lack the fenestrae of Torosaurus, and the epoccipitals are long gone, with no hint of them re-emerging and doubling in number to "become" a Torosaurus frill edge. You can check out some of these skulls here; the original drawing is by GetAwayTrike; please do note that this diagram isn't strictly Triceratops skulls, it also throws in the type skull of Nedoceratops and a referrable skull from the Scollard formation (which predates Hell Creek and true Triceratops), albeit with the missing snout restored like a Triceratops, and also includes Eotriceratops from the Horseshoe Canyon formation and Ojoceratops from Ojo Alamo.
Torosaurus and Triceratops adults and juveniles to the same scale (the adult Toro's beak is restored with the tip pf the juvenile's beak scaled up, as the original was eroded - other large Toro skulls have the same "condor" beak tip). Trike and Toro look really different as youngsters and even up even MORE different as adults. The frill is basically doing opposite things in both genera as it matures (extending and flattening vs. getting more upcurved and turning in on itself). Also note that even young Torosaurus had fenestrae in the frill, and that as adults, Torosaurus overall has a much larger frill than Triceratops, but a smaller face not counting the frill.

  

The big picture beyond Horner and "Toroceratops": Why the "hyper-lumper" approach is probably WAY off-base

Considering how much we know about both mammalian and avian biodiversity in recent ages like the Miocene, Pliocene and Pleistocene, and also given how much less terrestrial fossil material of any sort inevitably survives over time from older epochs like the Maastrichtian (and even less from earlier times), it may actually make the most sense to say that dinosaur faunas were MORE diverse and had MORE genera and species than we can ever possibly know - likely far richer and more diverse than mammalian faunas today, perhaps even more so than Pliocene and Pleistocene faunas. We just don't have as complete a fossil record when you go back into the mesozoic. Even so, recent discoveries have more than doubled the number of maastrichtian ceratopsids known. We're well past the point of "only Trike and Toro" in the US/Canada Maastrichtian time horizon, and any proper morphometric character analysis will show that there are a number of evolutionary steps between Torosaurus and Triceratops, which form their own unique genera.

Nonetheless, the view is still far from complete. Some species have probably never had a single individual get fossilized, which isn't all that strange when warm-blooded species sometimes last for less than a million years. Or we may only get one skull from an entire genus, because geological processes may have jumbled the rock layers so much that we will never have access to more than that, either due to their destruction in these processes, or their being buried in inaccessible depths, with no surface hints of their presence.

Now if that one skull happens to have some similarities with an already known genus, say, Triceratops (???), people will be tempted to gloss over the differences and lump it into Triceratops, even if some parts of it don't quite fit anywhere within known Triceratops populations and growth stages. But then, is it really an odd growth stage or an abnormal individual of Triceratops, or simply something else we don't properly understand yet? Then, when you actually find more growth stages and skulls of the new animal that show it's a unique genus with its own ontogeny pattern (like we now have with Torosaurus), what can you honestly say for a person who persists in denying its status as a separate genus or holding the clear differences to be one-off aberrations of no account? This might have been plausible when there were only one or two Torosaurus specimens known to science, but now there are over thirteen of them from different growth stages, and possibly comprising three different species (T. latus, T. utahensis, and "T. magnus", i.e. the MOR skulls).

Insistence on lumping two genera together "because they both have metaplastic bone" really is pointless. As it is, metaplastic bone is not exclusive to any one genus or growth stage, and we're already over-lumping extinct specimens based on arbitrary standards that would make no sense to a biologist studying living animals. There is less difference between the skull morphs of cheetahs and jaguars than you get between Trike and Toro - but nobody is proposing to lump cheetahs and jaguars into the same genus - DNA cladistics finds no less than FOUR other cat genera separating them.

The same phenomenon of morphological similarity "masking" generic diversity is found all over the place, whether in Birds of Paradise or in the host of antelope genera that cannot hybridize but look nearly identical when you get rid of the keratin horn sheaths (which would not fossilize). Of course you can achieve high morphological diversity in skeletons without genetic diversity, but aside from artificial selection by humans (as in the case of dog breeds) and a few extreme cases of sexual dimorphism, it's extremely uncommon in any vertebrates. We don't have DNA from dinosaurs, but if morphometrics are any clue, dinosaur paleontologists are lumping at a generic level, far more than they would be if such DNA existed. I am not suggesting we go back to having 16 species of Triceratops like in the 1950s (some of which were nearly identical to each other, and some of which were actually other genera like Nedoceratops). But on the generic level, things are definitely overlumped - something that even a good non-DNA-dependent analysis like Tschopp et. al.'s diplodocoid paper can expose very well.

If anything, the mainstream view of dinosaurs is actually already overlumped, even without Horner and Scannella's antics. As cladistic science gets more precise and uses more and better characters (and weeds out coding errors better), this is already becoming more apparent. Giraffatitan and Lusotitan are no longer part of Brachiosaurus. Galeamopus is no longer in Diplodocus. Traukutitan is no longer part of Epachthosaurus. Isisaurus is no longer in Titanosaurus. Brontosaurus - all 4 or 5 species of it - is no longer in the Apatosaurus wastebasket. It's an open secret that Mamenchisaurus and Omeisaurus between them currently contain around 10 other genera that should be spun off. And it should be obvious that not every ceratopsid with metaplastic bone is a growth stage of Triceratops. And of course, that Kosmoceratops is NOT a juvenile Utahceratops (what happened in Vegas... lol).

Dude, we don't even have the same frill stud arrangement, never mind number...
Do we really believe that metaplastic bone only exists in one species, or in just one ontogenic stage for any given species? Heck, even if Trike and Toro had identical ontogenic changes in horn and frill shape as they matured, or even if one's ontogeny pattern appeared to neatly transition into the other's (they don't, not even close), the fact that they both have metaplastic bone throughout multiple growth stages proves NOTHING conclusive in favor of lumping the two together. At best, even if the ontogeny changes matched or appeared to dovetail, and even if we didn't have inconvenient things like the ANSP skull or the Big Bend Toro juveniles to sour the deal for the Hornerites, it's still possible that these could be no more than two related genera with similar growth patterns. Even very old ceratopsids have metaplastic bone in their skulls, it's not proof of immaturity or an upcoming radical change in head shape - and even then, you could probably make a far better (though still wrong) morphological case for lumping Eotriceratops or Ojoceratops into Triceratops (despite the geographic and time discrepancy) long before you get to Torosaurus.

In many cases the metaplastic bone may have nothing to do with age, and far more to do with rapidly healing injuries and getting rid of infection (bone cells that naturally die rapidly and are replaced by new ones from below in a constant conveyor-belt cycle, are far less susceptible to infection - and we know these animals, with their vein-engorged frill bones, were just as susceptible to injury and possible infection from each other's horns as from a tyrannosaur bite to the face). Many of the irregular holes in "pathological" ceratopsid skulls of various genera and ages are bordered by metaplastic bone, did they ever stop and think what the connection was there? There's definitely a paper in that. So there are a lot more plausible alternate reasons for metaplasia that Horner and co. don't even address. Is their "Toroceratops" theory still possible? Sure, but the amount of contortion (both osteological and rhetorical) required merely to make it work also violates Occam's razor repeatedly. You'd literally have to ignore everything they didn't figure in their papers (even when they mentioned an inconvenient specimen in passing) and also ignore how ontogeny works in every other well-represented ceratopsid.

Get Away Trike! This is Toro time! Note that the T. utahensis material is smaller than most "teenage" Triceratops let a lone the older ones. The two MOR skulls have nasal horns and beaks unlike ANYTHING found in Triceratops - and they were still growing.

You want more details on Horner's lumpermania with Pachycephalosaurs too? Find it here and here.

Don't judge a dinosaur by its ankle.

Posted by Nima On Tuesday, April 25, 2017 2 comments

A change of pace from the sauropods for a bit: after a few questions from a follower of my work, I looked at Hutchinson (2011) again - the paper that estimated Sue the T. rex at 9 tons; I can't tell you how many times over the years I've had to point out the flaws in that extremely chubby model. (It's not that I don't like plump dinosaurs - when they're titanosaurs, they're downright gorgeous. It's plump predators that don't make sense - their survival depended on catching another dinosaur as fast as possible, and at any size, especially multi-ton megafauna, extra weight was exponentially costly).

It seems one of the reasons why Jack Horner and John Hutchinson don't accept a fast Tyrannosaurus is because the lower leg (i.e. ankle) supposedly aren't all that proportionately large, limiting its top speed (and that of other animals). While Horner isn't as hardcore in pushing the "T. rex was mainly a scavenger" theory as in the past, it's clear that this idea still informs much of his thinking and that of his proteges and colleagues.

Hutchinson basically relies on under-exaggeration. He makes arguments like "T. rex metatarsals are proportionally much shorter than those of ostriches, therefore T. rex can't run". Well nobody claimed T. rex was topping 70mph like a cheetah, but acting as if shorter metatarsals imply it can't run at all, is a red herring. And in large part it has to do with the Hornerites' love of straw men.

They take Bakker completely out of context, and pretend that paleontology today is full of people claiming that dinosaurs were supercharged cyborgs outracing hurricanes and crossing dimensions. That simply is not the case. Even the most radical paleontologists don't believe that, nor did Bakker ever make such bizarre claims. He simply stated the case for dinosaurs being warm-blooded, and at least as active as most mammals today (which shouldn't be such a big deal - lions are lazy, dogs are lazy, most mammals sleep a lot... there just don't get torpid like lizards and crocs can). There's nobody claiming that T. rex was running fast all the time - like most predators, it likely only hunted for a small portion of the day. All that we're saying is that a big 'rex was easily capable of 35mph when the time came to actually hunt and kill prey. Which is actually slower than an ostrich.

We're not saying this:


We're actually saying this:

Greg Paul 1988. Used for educational purposes only.

Yes they're fast, but not too fast to track mud or keep at least one foot on the ground for most of the stride. Again, not such a big deal when you consider how T. rex legs were actually built (long toes, huge muscle crests, metatarsals far longer than in any modern mammal over 2 tons, plus they had a built-in shock absorber with the interlock and the 5th metatarsal splint was basically a spring-loader for the outer ankle tendons to make running much more energy-efficient).

Why the "short ankle" problem isn't really a speed-killer:

What Hutchinson fails to pay attention to, is that tyrannosaur metatarsals are actually VERY long as juveniles, and shorten a bit as they grow into adults - they are not going from ostrich proportions to elephant proportions. In fact the "shortness" of T. rex adult metatarsals doesn't get anywhere near as short as in "elephant proportions". They're a lot longer in T. rex, and the actual toes are immensely longer than those of elephants. The toes of T. rex are about as long as the metatarsals themselves! Hutchinson seemingly ignores the impact of long toes and huge cartilage anchor surfaces on boosting speed and stride length.

This is what I call the "blind men and the elephant fallacy" - where you look at one part of an animal and make big sweeping assumptions about the animal based on just that one part, largely ignoring how it works together with the other parts. Ostriches have more elongated metatarsals but much shorter toes, whereas tyrannosaurs gradually shorten the metatarsals but lengthen the toes (as well as having much bigger muscle crests on the knee) - this reduces the stress on the metatarsus and helps distribute the higher mass more evenly, as well as boosting the stride length back up. It all evens out in the end, and the 'rex can still run - just more easily in the 35mph range than a 40 or 50mph range. There is a bit of reduction in speed versus the ostrich, but not THAT drastic like Hutchinson claims. Smaller tyrannosaurs with longer metatarsals like Albertosaurus and Alectrosaurus may well have been able to rival the ostrich in speed, at least for short bursts. And of course tyrannosaur phalanges are far longer and more flexible than those of either elephants or rhinos (and rhinos are flexible runners despite their short toes).

The metatarsals of T. rex are still much longer than what you get in an elephant. On top of that they are interlocked, which only happens in cursorial animals, and it's a biped, which means no weight-bearing forearms to limit the hindlimb stride length. And finally the ankle joint is a lot more flexible than in an elephant, so clearly there was some running going on. And yet Horner and Hutchinson keep arguing that their speed and movement was basically one and the same.




Tendons and muscles:Most of the lower leg segments are covered in tendons rather than muscles. However, we need to realize the whole thing is interconnected, so that we avoid the blind men and elephant fallacy. The main thing to remember is that these long tendons on the lower leg are like big cables hooked to the muscles further up. Generally longer lower leg tendons imply more speed and flexibility, but they do need big muscles on the femur and shin to power them. Now compared to a spindly ostrich, T. rex had attachment surfaces for thigh and shin muscles in spades. And an huge caudofemoralis. And a huge tail to anchor all that and make running even more energy-efficient. What does an ostrich have to anchor its rear thigh muscles, that tiny pygostyle? With all of these advantages for T. rex, we soon realize the shorter metatarsus is not as big of a disadvantage as Hutchinson makes it out to be.

The main enemy for any big theropod is mass. You need to get bigger to tackle bigger or more well-armored prey, but as mass increases, limb segments must become more robust, the ankle gets shorter and more compact because most of the shear stresses of running are directed there - if no other changes were made to the leg as tyrannosaurs evolved to get bigger, this on its own would reduce stride length, and require a major sacrifice of speed. But of course other changes were made. Considering all the ways that T. rex compensated for the shorter metatarsus (longer toes for distributing the stress and increasing stride length, tightly interlocked metatarsals, expanded muscles on the hips and knees, the MT5 spring-loader, the huge caudofemoralis) it's pretty clear that the net total sacrifice in speed wasn't all that great, and fast running was still priority #1. Again, we have to look at how the entire leg evolved and functioned, over-focusing on one segment is very misleading.

The toes of T. rex were not flat-footed or stiff - they were flexible, active parts of the leg stride, and in fact proportionally oversized relative to other giant theropods of similar mass. Note the huge caudofemoralis muscles. Even at half the size depicted here, they would yield considerably more torque than an ostrich scaled up to the same hip height. Image by Scott Hartman, used for educational purposes only.



I don't know if Hutchinson ever argued that not having big muscles on the ankle made T. rex slow, but if he did, that would be an incredibly bogus argument. The ankles of fast-running animals NEVER carry big muscles. They are almost entirely covered in compact, elastic tendons which are powered by muscles much higher up on the leg. Ostriches, horses, big cats, it makes no difference, the lower 50% of the leg is all bone and tendons. Big muscles on the ankle would serve no purpose, as the ankle itself doesn't drive the leg stride, the femur does! The only things that ankle muscles could affect are the toes, and hence having a really big muscle there would be pointless, unless the toes needed to be super-prehensile for climbing trees and the like. I don't think Hutchinson ever argued that. Hutchinson's main argument about ankles seems to be that T. rex's ankle bones were too short to allow the strides needed for high speeds - that's still a weak argument because (a) it ignores toe length, which is very substantial in tyrannosaurs, and (b) it ignores the fact that T. rex metatarsals are far longer and more flexible than what you get in elephants, and animals don't evolve such specialized metatarsals just to waste them or keep them immobile.


T. rex's metatarsals were ALSO much longer than those of duckbills like Edmontosaurus, which were the fastest large herbivores of its day.




The real paradox of the Hutchinson/Horner T. rex: What's really odd is how these people spend so much time and effort trying to throw T. rex under the bus merely because of its size, and omit all mention of at least 75% of its high-speed adaptations, when there were other large theropods (some of them smaller than T. rex) that actually were designed to be slow. Majungatholus and Rajasaurus were clearly slow animals, they have much less metatarsal and toe length than T. rex, and in fact they look more like a zeppelin with legs than a hunter, yet they clearly filled in a top predator niche. Then we have giant allosauroids like Acrocanthosaurus and Giganotosaurus, which actually did have relatively small toes for the leg length, and relatively stiffer legs than tyrannosaurs with less cartilage attachment area (makes sense, they were hunting sauropods for crying out loud!) and yet were still probably topping 20mph easy if their trackways are any clue.

A real slow-running giant theropod - Acrocanthosaurus, hunting Pleurocoelus. Note the compact feet and short metatarsals. Even with this leg design, it could easily outrun a human. Painting by Greg Paul, used for educational purposes only.

And Spinosaurus... a born slowpoke, eating giant lungfish and amphibians, no way to imagine how a spinosaurid could outrun a tyrannosaurid with that low-hunched body... but I get the idea that Hornerism is less about hard facts and more about getting famous (if Horner's input in JP3 was any clue) and the quickest way to do that is to start discrediting the anatomy and fearsome reputation of the world's most famous and "over-fanboyed" dinosaur species.




Spinosaurus by Miyess - one of the more reliable reconstructions out there. It is unlikely that this relatively long-bodied, short-legged animal could run fast, though contrary to some recent data-masking papers, it was almost certainly still a biped.

Well perhaps there's actually a good reason T. rex is so famous. It's not the biggest predator, it's not the fastest, and sure as hell isn't the prettiest, but simply the way it's built, the toughness of the skull and teeth, the binocular vision, its unusual speed for its size, and the sheer amount of abuse its body could take above and beyond other theropods before giving out, is truly remarkable for so many reasons. Of course other big theropods weren't forced to evolve to deal with 90% of their prey being a double-sized charging ceratopsid with a solid bone shield on its neck, but had the same pressures existed in other mesozoic faunas, T. rex would have had many imitators.

The funny thing is, none of this ever made me a "fanboy" of T. rex. I was never crazy about theropods, and even among tyrannosaurs I don't like T. rex all that much (ironically the same sentiment Horner expresses). I never had any delusions about it being "invincible" (indeed you could argue the only reason it developed in such an "overkill" direction was due to its prey animals nearly doubling in size, and sometimes armor, over the past few million years, and there were at least two contemporary species in the southern part of its range - not to mention many more in foreign lands and epochs - that could annihilate even the largest T. rex in one blow). Yet I can still admit that it's a very exceptional species, heavily specialized for crushing rather than slashing, and yet sacrificed less stride length and speed than just about any theropod of similar mass. The conditions that produced T. rex were very unusual. Some theropod would inevitably fill this sort of role. It turned out to be T. rex. I can admit this. What's stopping the Hornerites?


How big was the French Monster?

Posted by Nima On Wednesday, April 12, 2017 7 comments

Earlier you may have heard of a truly colossal sauropod species known as the French Monster. First it appeared to be a titanosaur, though now it looks to be a basal somphospondyl, along the same lines as Chubutisaurus and Paluxysaurus.

It's a massive creature no doubt, but one thing severely lacking from the announcements of the finds several years ago (besides a description paper and a name!) was a set of proper measurements for the bones. We do have some good pics though, from the dig site in Angeac-Charente, which is apparently wine country. It's tempting to think that fossil-rich soils make for top-quality grapes... lots of minerals there. And tannins... look at how dark those bones are, surely from all the tannins, it must be. Most significant were two femurs from different individuals, one of which was well-photographed and appeared to be about 2.2m long, the other being considerably larger. Below you see the smaller one:








Photos of the larger femur, estimated at 2.6m, did not materialize.

However there were some rare glimpses of other gigantic bits.




Some of the biggest caudal vertebrae ever found, and quite possibly the biggest toe bone ever found (the darker bone near the center).



Then we have this gem, which it the lower end of either a tibia or a very worn-down femur. Again, huge.

The foot claws are just enormous. This one is as big as a sewing machine. And the toe bones... well just look for yourself. That same dark one you saw above is a cinderblock! The caudal centra also outclass those of Futalognkosaurus, Paralititan, and "Antarctosaurus" giganteus. And unlike those specimens, these French Monster centra are mostly mid-caudals, NOT proximal caudals. Anyone still keeping score? And why are the neural arches seemingly cut off on most of these? Were they sutured and still growing ????




One toe bone from this sauropod (right) is more massive than the whole femur of a theropod found at the same site (left).

Toe bones as big as cinderblocks.




There are also some big teeth from the site, with the same black mineralization as the first femur, and encrusted with some sort of comglomerate. They look similar to brachiosaur teeth, which is not surprising given that the unique features of the femur put it closest to the Chubutisauridae, which are only a couple steps removed from brachiosaurs.



We also know that a cast was made of the 2.2m femur. For some years, little more was known.



Gunnar Bivens gave me this link to some sources: dml.cmnh.org/2017Apr/msg00032.… which include information on the French Monster. Not only do they verify the size of the 2.2m femur known, as well as the other materials, but they also verify the estimate of the larger femur at 2.6m long when complete - surpassing the femur of Argentinosaurus.



Given that the French Monster appears to cluster closest to Paluxysaurus and Sauroposeidon and shares several diagnostic femur features in common with both of them (there is a juvenile Cloverly Formation femur from the latter), a good place to start when scaling the French Monster is the already existing Paluxysaurus skeletal from Steve O'Connor:



Assuming you use the Paluxysaurus proportions as seen here, and a GDI based on the mounted skeleton, the "adult" Sauroposeidon from Oklahoma would scale up to 26.9m 47.5 tonnes, as per Franoys. The same model yields dimensions for the two French Monster specimens known from the 2.2m and 2.6m femurs at [28.5m and 56.5 tonnes] and [33.5m and 85 tonnes] respectively. Yes, I said 85 tonnes. That's up in Argentinosaurus territory, and for a dinosaur that almost certainly had a slimmer rib cage - which would require it to be a hugely tall animal, and in lateral view its slimmer torso would actually have to look bigger and deeper than that of Argentinosaurus to get the same volume and mass.

Paluxysaurus mounted cast. Note the relatively narrow brachiosaur-like rib cage. The fat rib cages of derived titanosaurs appeared far further up the evolutionary tree.
Those are impressive sizes. Though I suspect they may be a bit conservative, as it's unlikely that an adult Sauroposeidon had the same proportions as Paluxysaurus (though the juvenile Cloverly Sauroposeidons apparently did). I would expect more elongation in the neck and tail for the "adult" Sauroposeidon, and the four cervicals we have were likely not the longest ones in the neck. Similarly, the French monster would likely top those estimates based on likely neck elongation assuming its juvenile form was something like the juvenile Sauroposeidons from Cloverly.



Paluxysaurus

Sauroposeidon

I would estimate Sauroposeidon somewhere around 28-30m, and the two French Monsters known from femurs at around 33m and 36m respectively. And there is a huge rib pictured on one of those French websites that's AT LEAST as long as 4 people! www.bulbintown.com/projects/le… Am I seeing this right? This would have to be some kind of record breaker, even bigger than the larger femur specimen. Think about it - the larger ribs in a sauropod typically were in the same length range as the femur, a bit more when you account for their curve length. But if a sauropod's femur is 2.6m long, its unlikely that a 4m+ rib would come from the same specimen. So we have a third gigantic individual, which would have easily outclassed the other two.

DAAAAAAAMN that's a big rib. That's 5 people lying next to it, but the guy at the top may be next to a dorsal vertebra as the rib head seems to terminate further down. At the bottom, the end is broken off! So there was even more...

This is great news. Now we have a basal somphospondyl to rival Argentinosaurus. Even if you ignore the rib specimen and go based only on the individual that provided the larger of the two femurs, 33.5m and 85 tonnes (?!?) for a chubutisaur is no joke.

And that crazy-huge rib... that thing must be 6m long? Admittedly it's pretty flattened from millions of years of being buried under tons of rock, but even when uncrushed and in its natural curve, that's at least a 4m-deep rib cage in strictly linear side-view dimensions. I know there are a lot of issues with scaling sauropods off of just rib pieces, but keep in mind, this rib looks to be 6m long and is still missing the bottom end! So conservatively at 4m uncrushed and articulated, what does that come out to, a 112 foot or 36m animal using my B. alithorax as a model (it has a similarly long torso), but the neck would be a lot longer in Sauroposeidon or the French Monster...

... so using Steve O'Connor's Paluxysaurus skeletal is a better model (more elongated neck plus proportionally shallower ribcage), then we have a total length/longest rib length ratio of 10.24, so we get a 41m animal! This means it's about 1.22 times the length of Franoys' estimate for the larger femur specimen (remember, that's still a conservative estimate). Cubing that for all 3 dimensions, we get 1.81 times the volume of that specimen, and thus 1.51 times the mass.  = 154 tonnes. THIS IS INSANE! The Oklahoma apatosaur and the newly legendary BYU Barosaurus specimens might as well roll up and cry. Move over, boring diplodocid fern-slugs. Macronarians have the crown once again!

Folks, we may have the biggest dinosaur ever here. I'm not claiming it "must" be 154 tonnes, it may not be much more than 100-110 tonnes depending on how these animals grew allometrically. But that's still in Puertasaurus/Mexican Alamosaurus/biggest individual of Chubut Monster territory. And the 41m length exceeds all of these animals, and is still only based on using the Paluxysaurus skeletal as a model, still ignoring how much distal material is missing from the rib, and still scaling up from Franoys' conservative estimate for the larger French Monster Femur. With better photos we may be able to bring down the size, but for now... WOW. 41m and possibly in excess of McNeill Alexander's (flawed) "upper limit" for sauropod masses. I'm not joking, this could be the find of the century.

At least one
of these French Monsters is a real record crusher, probably the individual with that huge rib (assuming it's not a petrified tree, which is unlikely given all the attention it's getting from the dig team in that photo, plus its apparently rib-like proximal end and close proximity to an obvious distal rib fragment next door). There are no pictures of the rib fully prepared, or of the 2.6m femur. But we know how to scale them so I'm confident this animal could have gotten bigger than Argentinosaurus and perhaps even any of the other mega-titanosaurs.

For now here is an image of a museum display for the smallest of the three French Monster specimens examined here, the 2.2m complete femur, with a fibula from the same individual. Even this animal is huge, and it's dwarfed by the two bigger ones. And chubutisaurs actually had a pretty low femur-to-body length ratio, which means they outclassed most sauropods in total body length, for any given femur size.


And now imagine one twice this size, with that 4m rib... just to keep one thing in mind, a 4m rib also blows the ribs of Supersaurus (the prior record-holder for deepest ribcage), the Potter Creek brachiosaur, and "Huanghetitan" ruyangensis clear out of the ballpark. Using Paluxysaurus neck proportions, the giant rib individual also would have beat out Supersaurus, Daxiatitan, Yunmenglong, and "Mamenchisaurus" sinocanadorum for neck length (and obviously Sauroposeidon as well). And a 4m rib is a conservative estimate for that photograph, not accounting for the broken lower end! You have not even begun to see the biggest dinosaurs, it seems to say.

Was the French Monster the biggest? Did some individuals of the mega-titanosaurs get larger? Dump your comments below, but now I think you're pretty clear on where I stand. There are already plenty of pics here for the limb and tail parts of smaller individuals, which are unquestionably already in super-sauropod range. Unless that rib turns out to be anything other than a rib (and if a rib that thick ends up being a cervical rib rather than a dorsal rib, that's even scarier), we are looking at the new biggest dinosaur. Full stop.