Don't judge a dinosaur by its ankle.

Posted by Nima On Tuesday, April 25, 2017 0 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 5 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.

How much time did sauropods need to spend eating?

Posted by Nima On Tuesday, March 21, 2017 1 comments

This is a question we hear a lot, especially from dino-fans in awe of the size and scale of some of these creatures, which can only go up after seeing one in a museum.

However huge you think they are, they always look bigger in person.

We've all heard they needed outrageous amounts of food just to stay alive (and that they shook the earth with each step...) but how much time did these giants really need to spend eating each day?

The answer is, a lot less than you might think, even with being warm-blooded... but it depends on the species. A lot of people imagine that sauropods were so big that they had to spend all their time eating, or that a warm-blooded metabolism would demand more food than they could ever possibly take in. But this simply isn't true! Now of course sauropods didn't all have the same energy requirements, but most would have been in a similar nutrient/tissue conversion range, and in general the worst-case formula goes like this:

A big warm-blooded herbivore needs to eat about 2% of its mass in food per day to keep going. (A 5 ton elephant = 5,000kg, needs minimum 200 pounds or 100kg of food per day, that's 2% or 0.02 of the elephant's mass). Now this is a very high estimate of the minimum intake - it assumes sauropod digestion was as bad as that of elephants or horses, but it was likely much more efficient, this is just a worst case scenario to show how much easier feeding was for sauropods than we often imagine.

Going by a similar measure for sauropods, we get the following:


We'll use the Berlin Giraffatitan HMN SII (subadult) as a test case, since we actually have a complete mouth and most of the skeleton: Since we have the basic 2% formula already, we just need to know (1) the animal's mass, (2) the volume of its bite, (3) the time it took to swallow each bite.






So how heavy was it?
Now if you look at the subadult Giraffatitan, as restored by Paleo-King, it's ~33 tons (lean mass). We could use another skeletal restoration that estimates it lighter or heavier, but since this one is the best, most detailed, most beautiful, most thoroughly researched and lifelike, and likely will not be surpassed for another Cosmological Decade or so, this restoration is the gold standard to use.
So, 33 tons or 33,000 kg x 0.02 = 660kg of food = 1320 lbs of food required per day, or around 6/10 of a ton, minimum.

So how big was each bite?
The mouth of HMN SII (skull HMN S116) is big. Very big. Here's where most paleontologists get lost - they assume based on modern mammal rates of feeding that sauropods needed many hours to feed - not true, since despite having proportionally small heads, sauropods had much bigger mouths than modern mammals. The skull of SII/S116 (left column, second skull down) was at least 0.8m long, that's pushing 3 feet - with the toothy portion of the mouth being about 0.4m long, and just as wide, and about a foot deep. So its volume is about 1.47 cubic feet, bigger than a laundry basket = Big enough to bite off 70 pounds of conifer leaves/needles. Though lets be conservative and say it was on average 50 pounds per bite because not every bite was on full branches.


Heck, even the smaller HMN t1 skull looks like it could gobble up close to 50 pounds without much effort!



So how long did feeding take?
Each ~50lb bite takes 30 seconds max to hack off and gulp down, probably it was much faster, since these animals didn't chew, but we don't know if their brain stem could coordinate breathing independently of swallowing (most reptiles and birds can pull it off, some mammals can't) so worst case we'll give him 30 seconds per bite for a breather. So that's 2 bites or 100 pounds of food per minute. 1320 pounds daily requirement, divided by 100 pounds per minute,  = 13.2 minutes to eat the minimum food to stay alive, assuming elephant-like digestion (which is, again, far less efficient than we'd expect for any sort of archosaurs).

Of course they probably ate a lot more than the minimum. But even if they took in twice as much on average, that's 2,640 pounds or 1,320 kg... which translates into 27 minutes of feeding. But lets be REALLY conservative and say that most of the trees in the area have already been depleted of branches up to the Giraffatitan's feeding height... so our friend SII has to spend half of the time moving around and looking for fresh trees that have not been fed on. This doubles the feeding time to just under an hour. If the area is totally depleted and SII has to walk around another 5 miles to find enough food, that's another hour (5mph is easy for a big brachiosaur, with that huge stride length, it's next to no effort). So even in a worst case scenario with competing herds eating everything, you travel 5 miles from where you were yesterday, foraging and feeding time is under 2 hours, eating twice the minimum needed. And as for bigger sauropods, like an adult Giraffatitan (HMN XV2?) or even the really huge titanosaurs like Argentinosaurus or Puertasaurus? They were larger but also likely had bigger mouths to match. The width of the neck in many advanced titanosaurs indicates there was probably a big-mouthed head at the top. So realistically I don't see feeding taking much more than 2 hours for these species either.

Giraffatitan by Brian Franczak - an example of a "worst case" feeding scenario

So we're talking around 2 hours max, but usually much less time than that. And that's assuming both a warm-blooded metabolism and a fast, inefficient digestive system like that of elephants. In reality sauropods probably had much more efficient digestion like ostriches, and so may have needed less food and feeding time even with a fast metabolism (Foster, 2007 says that even the heavier Brachiosaurus altithorax needed only 400kg a day, not 660kg - so my minimum is likely on the high end anyway). So 2 hours is really a worst case. I know, shocking - especially if you grew up with all those awful, horrible outdated books that claimed sauropods needed to eat all day long or spend their whole lives barely moving in a lake surrounded by water plants lest they burn one calorie too many.


 Mark Hallett's and Dougal Dixon's Giraffatitans - less accurate anatomy, but more likely feeding scenarios.

We can forget about all the crazy stories of sauropods needing to eat nonstop 24 hours a day without resting, it simply isn't true, not even close. 2 hours per day is more than enough. In fact if you added in the minutes needed to drink water, the total would still be unlikely to top 2 hours. The rest of the day is sleep and play, and whatever else sauropods liked to do. Shocking, I know. Life actually seems "normal" for them. The facts really are stranger than the fiction.

I am now "officially" as famous as Dr. Bakker!

Posted by Nima On Saturday, January 14, 2017 0 comments

I just came across this little paper, not about any particular dinosaur species, but about Paleo-art itself. Link is:

http://digital.csic.es/bitstream/10261/120877/1/Manuel_ejip%202015.pdf


Although this came out a couple of years ago, it's still an interesting read. A survey (likely not a terribly scientific one, due to the small number of respondents) was sent to 115 paleontologists and "naturalists" (not sure how they defined that) in different countries, and apparently these are just the PhD professors in the field. This was carried out by a group (apparently in Spain) known as the Meeting of Early-Stage Researchers in Paleontology.

One of the questions asked is to name up to three paleo-artists whose work one recognizes. The results are on page 9 of the paper.

Interestingly Mauricio Antón got the most "recognitions" in the survey, 60 in total - apparently because he had illustrated papers for many of the scientists (Raúl Martín, in second place, got only 20 recognitions). I suspect this exponentially leading score may also be a bit biased, since Antón helped with the production of the paper, being among a few "special thanks" individuals who provided "bibliographic recommendations and for sharing their paleoartistic knowledge." Knight, Burian, and Zallinger rank high because they were the early pioneers of dinosaur art, so their age and niche exclusivity for so many decades did make them famous - but their work is woefully outdated now, and was far less scientific than it could have been, even in its own time (consider all of those dislocations), so it is odd why so many scientists would recognize their art as scientifically relevant in our time. Benjamin Waterhouse Hawkins was mentioned for some odd reason, even though he was less an artist than an exhibit builder, and his work is even more outdated. But more interesting still, was how few people mentioned some of the other "greats" in Paleo-Art. Andrey Atuchin, Felipe Elias, Dr. Robert Bakker (himself a prolific illustrator), Bob Nicholls, James Gurney of Dinotopia fame, William Stout, and Dr. Mark Witton all got only one (1) recognition each - from among over 115 respondents. And guess what - yours truly also got one. I was not part of this survey so I can at least say with total confidence that someone else "voted" for me. Also, some established artists of the pre-internet age who are still around, such as John Gurche and Mark Hallett, only got 2 votes, despite their work being in so many National Geographic issues.

Interestingly there was no mention by the respondents of Andrea Cau, Brian Franczak, Larry Felder, Donna Braginetz, Ely Kish (I sort of expected that), Michael Skrepnick, John Bindon, Fabio Pastori (good riddance) or Berislav Trcic. Skrepnick has illustrated papers as well as popular articles in NatGeo and elsewhere so his absence from the minds of paleontologists seems odd. Also Wayne Barlow wasn't mentioned, which I suppose makes sense as he never collaborated with paleontologists on anything more than a children's book, though his skill easily surpasses many of the people on the list.

The list is hardly a measure of skill (and there are some people on the list who have less skill than any of these names, or are complete unknowns to me) but it is a measure of the impact of one's work on the field, at least as can be gleaned from the paper's small sample size (seriously, they should do this survey at SVP meetings, they will get a lot more than 115 people). And now I am apparently just as important as Dr. Bob Bakker, the Godfather of the Dinosaur Renaissance himself. And James Gurney, world-renowned creator of "dinosaurs meet steampunk before anyone knew about steampunk". And the digital Grand Master, Andrey Atuchin. All of whom got one point each. Yay.

Giraffatitan's weird head gets even weirder

Posted by Nima On Saturday, July 9, 2016 4 comments

In the last post on Giraffatitan, we focused on just how strange the head is, and explored some hints about the ontogeny of the animal's face.

However after a deeper exploration of the actual fit of the skull bones, dumping all stylizations and previous conventions of illustrating this iconic brachiosaur, a few things started dawning after being hidden and dissociated for mission of years. Giraffatitan is even weirder than I thought last time.

Not that it's easy to tell from three fragmentary skulls and a fourth that, while largely complete, has undergone massive distortion from crushing. That skull, HMN t1, which was reconstructed in the 1930s, was cast in fiberglass recently by Research Casting International (RCI) in their 2007 revamp of the Humboldt Museum's dinosaur hall - one that was long overdue. The cast was scaled up by around 15% or so on a 3D printer to match the body of the larger HMN SII, whose associated (and far less complete) skull SMN S116 was significantly larger than HMN t1. Apparently an earlier cast of HMN t1 existed as far back as the 30s and stood in a glass case in front of the old mount.




The problem, of course, with HMN t1 is the crushing and distortion, which results in an asymmetric skull today.



From the sides the distortion is more apparent.



 Left: moderate vertical crushing in the upper jaw. Right: more severe crushing in upper jaw, including lateral splaying of the lip region and artificial progmathism and splaying of the premaxilla and snout tip. This actually results in a different observable lip line on one side than on the other.  Of course the teeth are seriously falling out of their sockets here. They did not extend out that far in life.

Another problem is that the warping and crushing is in more than one direction, so that you are literally getting a different face looking at it from different angles. Judging the ideal "shape it should be" from a few photos at odd diagonal angles is asking for trouble. So how do you reliably uncrush this thing evenly, without photographic distortion on top of physical distortion, and get an idea of what the skull originally looked like?

Well you can go based on photos by amateur photographers from slightly off angles in a small cramped basement room, or go by professional drawings from the past, or use published photos. I prefer published photos from the paper, but for Janensch (1935) these are rather old and grainy, and I assumed a better result could be had from bigger, newer, sharper full-color photos, or from supposedly well-measured professional drawings of the skull in its hypothetical pristine form.

BIG mistake.

Initially the design for the Giraffatitan skulls in the skeletal redux went like this:

insane....
So I literally redesigned the skull four different ways before getting something that I could feel reasonably satisfied wasn't based on distortions and actually looked natural, like the interior of a living face, not some emaciated plastic toy. Something that didn't look out of place on an appropriately fleshed out Giraffatitan.

The first version was on the old Giraffatitan skeletal I posted. The drawing I used for inspiration (artist unknown) was rather grainy, and I ended up exaggerating the proportions and the shape of the teeth somewhat. On a 1950s brachiosaur drawing this head may have looked okay, but the shape of the nose and the jaws just seemed contrived based on what I had seen of the skulls - and the snout was a bit too beak-like in profile.

The second version came to me after hunting down a photo from a not-quite-profile angle on the web. Upping the contrast and then editing out the further premaxilla yielded a good snout profile, and this time with the nasal arch editing looking much better. The nasals of HMN t1 do appear a bit flattened so will need to be edited each time. Here the angle itself helped counteract the appearance of the crushed snout that plagues ride-view verbatim restorations.We end up with more robust jaws and a more believable gumline for a brachiosaur. But still, this image was based on a photo from an angle and so necessitated some distortion due to perspective as well.

Out of frustration some may resort to simply taking Janensch's drawing of a "de-crushed" composite skull as the true path. The problem here is that Janensch made a glaring error - the snout in his engraving is far too long. I shortened it a bit, but even then this version seems to shrink the nose and the rear skull and overgrow the snout and jaws. None of the Giraffatitan skulls have these proportions, they all reflect proportionally shorter jaws than that.

Finally a real edge-on profile photo of the right side of the skull surfaced on the internet. It was poorly lit and grainy, but it was the best profile available at the time - the picture was taken from some distance, so no "fish-eye" shape distortion, and also no angle distortion. Of course the crushing was still there, but now there was no extra visual illusion on top of it to undo. Rapidly this became a line-drawing, but then the flattened upper jaw and prognathic snout tip had to be corrected. With the jaws deepened to make up for crushing and possible erosion, the teeth back in their sockets, and the back of the skull at its proper proportions, this fourth attempt looked like the answer.

Based on it, I crafted the previous incarnation of the ontogenic sequence of Giraffatitan skulls, with some more modification.


Unfortunately, this assumed the other skulls were more or less identical to HMN t1. And it also utilized an excessive amount of morph change from the original despite compensation for crushing being necessary. A better photo was needed. Actually several better ones were needed for these skulls turned out to be unique individuals with different faces.

Looking closer at photos of the skulls, it became clear that this little happy family just looked wrong.

The largest skull, HMN S116, does not look like an exact copy of HMN t1. It is clear we are seeing one species here, but there is individual variation, ontogenic variation, and maybe even some sexual variation. Just looking at the individual skulls and fragments, this is not readily observable. But just wait til you try to reconstruct the gaps.


Pretty messy, pretty horrible. But let's clean up the process a bit...

How to draw accurate Giraffatitan skulls without going insane

It is often helpful to invert colors in MS Paint and work "in negative" - it allows you to avoid distracting and potentially artificial structures and visual illusions caused by too many changes between black and white regions. Now the process of following the skull photos much more closely than in the last set of reconstructions becomes very simple. The published photos from Janensch (1935) are rather grainy compared to more recent ones, but at least they were taken professionally, from proper lateral angles at a good distance, and thus can be used to make a skull recon while both removing crushing and avoiding the pitfalls of having to worry about camera angle distortion from amateur photos of the skulls (or of t1 anyway, since the other skulls have never been reconstructed or cast, and are off limits to the public). Reversing one side of the skull and overlapping it in Paint and Pixia allows you to get an idea of the relative crushing and distortion in different directions on both sides of the skull, and average their outlines to compensate for it. Some additional decrushing was also done with the snouts, which were all a bit more flattened than normal.

So in the end we have a rather different set of skulls than the speculative versions in the last post. Interestingly enough, the large HMN S116 has an absolutely huge nose, even by the standards of the more famous HMN t1. While the nasal arches are not preserved in S116, the enormous and massively buttressed shape of the upper maxillary process means that the nasals begin higher up on the skull than in HMN t1. In addition, the higher slope of the maxilla's upper surface indicates the nasal arch was also more elongated from front to rear (relative to the snout) than in t1. This overall indicates a nose that was oversized in all dimensions relative to t1. The lower jaw by contrast seems a bit undersized.

This can be easily explained as the result of ontogeny, as the large S116 - probably the same animal as the huge mounted postcrania labeled HMN SII - is actually still growing, its coracoids being unfused to scapulae, though it is still more mature than the smaller t1. However, there is probably more to this bulbous difference in nasal size than just ontogeny.

Note that the immature HMN S66, which is smaller than t1, also shares the large S116's trait of very large and tall upper maxillary processes and thus nasal bones that are rooted very high on the head. The nasal of S66 is flattened, which is to be expected as it has disconnected from the premaxillary (whose upper portion, making up the lower half of the nasal arch, has long broken off and disappeared) . However judging by the high-sloping upper surfaces of the maxillae in this specimen, the full nasal arch was likely also proportionally taller and longer than in t1. The fact that both the more mature S116 and the slightly smaller and (likely) less mature S66 have significantly more massive and taller upper maxillary processes and larger noses overall than t1, as well as a different shape to the maxillary processes altogether, indicates we may actually be looking at sexual dimorphism - perhaps with the large S116 and the much smaller S66 both being males, and the intermediately sized t1 being a female.

This possibility indicates that dimorphism in Giraffatitan could have progressed, at least in the skull, from a relatively young age. HMN SII/S116 was roughly 74ft. long, even with the substitution of the smaller correct tail HMN Aa for the oversized tail "HMN Fund no" used in the mounted exhibit. Judging by the unfused coracoids (and overlapping unfused scapula from the similar-sized HMN Sa9 - which may also be part of the same individual), the animal was likely a subadult, perhaps in its tens or early 20s assuming these animals took around 30 years to reach adulthood, which seems to be the indication in osteological sauropod studies. HMN S66, by a very rough estimate, was probably around 50ft. long, and may have been in its early teens. Unfortunately there has not been much histological work done on Giraffatitan to determine the ages of various specimens so these are speculations for now, but it is likely that if we are seeing sexual dimorphism in skulls, it probably began well before Giraffatitan reached physical maturity.

Of course, adult Giraffatitans (of which HMN XV2 and "HMN Fund no" may be examples) would have had even bigger heads. As these larger specimens, likely ranging between 85 and 90ft. long when alive, are not known from shoulder material, whether they are full-grown or not is impossible to determine. So the typical adult size of Giraffatitan - let alone its upper limit - is not determinable with any certainty, and neither is its maximum likely adult skull size. But we can at least scale up S116 to get a rough model of how big XVs's skull may have been.

Eventually thus we end up with an ontogenic sequence, which can be compared to other brachiosaurs known thus far:



Yes, those are some pretty huge skulls. And it makes sense, as they needed a big head, and especially a big mouth, to pack down all the food needed to grow to such huge sizes and beyond. HMN XV2 could have taken in 30gk in a single bite (though given how Jurassic conifer tendrils were built, much of each bite would have been air). And things get even stranger when you realize that even in the smaller HMN t1, the braincase was about 500 cc's, far larger than in many dinosaurs, and comparable to a chimpanzee brain, which is considered pretty large in terms of raw size. Nobody will ever see sauropods as "pin-headed" ever again.


So to recap, not all Giraffatitan skulls were copies of HMN t1. There is significant variation, enough to suggest a possible dimorphism in addition to ontegenic changes.