Giant dinosaur speed discussion thread

[Infinity Blade]

Discuss anything pertaining to the locomotory potential of giant dinosaurs here.

I guess I'll start off. I'm particularly interested in that of mega theropods. After reading some works by Greg Paul (and to a lesser extent, Robert Bakker) regarding limb morphology and biomechanics of giant theropods (a lot of it regarding Tyrannosaurus), I'm convinced that they should have been notably faster than say, elephants, the only living terrestrial animals that approach them in size. I recently came across Christiansen (2000) (link), who concluded that, while giant theropods had femoral strength indicator values significantly lower than those of their smaller kin (making them less fleet relative to size), they would still have been able to achieve high speeds in absolute terms due to their sheer leg length and other aspects of their locomotory limbs (these would allow them to move fast even without a substantial suspended phase, according to him). His findings are also consistent with theropods running faster than elephants.

Body mass and strength indicator values of the three hindlimb long bones have been calculated for a large number oftheropod dinosaurs and compared to extant mammals of varying size and locomotory capability. Small to medium sized theropods have strength indicator values comparable to fast-moving ungulates and carnivorans, whereas all large genera have considerably lower strength indicator values, roughly comparable to elephants and hippopotamuses. This suggests that their locomotory potential was reduced compared to the smaller forms. Limb bone ratios of a large number of extant mammals clearly differen- tiate fast-moving forms, classified from their anatomy as subcursorial or cursorial, from forms capable of less rapid locomotion, classified as graviportal and mediportal. Limb bone ratios for theropods, however, somewhat contradict the above, as all theropods group among subcursorial mammals. Calculations on estimated peak locomotory performance indocates that even large theropods could have been fast moving without having to include a suspended phase in the stride, thus not subjecting their appendicular anatomy to large amounts of stress, due to their very long limbs.

What surprises me is giant theropod femora supposedly having strength indicator values only on par with those of elephants. But I remember it being said on the giant theropod thread that the femora of Sue were even thicker than the humeri and femora of larger mammoths. Their uncolumnar limbs would also suggest that their femora would be subjected to more resistant to bending and torsional stress than the upper long limb bones of columnar legged elephants (which excel at dealing with compressional stress). How can this be?

Discuss.

EDIT 6/23/20: This edit is mostly just an excuse for me to post a couple things here (and get rid of a few tabs), but this may still be relevant to giant quadrupedal dinosaurs.

Recently I was in a brief discussion about whether or not quadrupedal dinosaurs would have been able to gallop. It was brought up at one point that since dinosaurs did not have backbones flexible in the sagittal plane, they would not have been able to gallop like mammals can.

The statement regarding backbone flexibility may be true. However, I mentioned that there are mammals that gallop without a flexible spinal column. Such an adaptation is helpful in increasing stride length (cats are an excellent example), but sometimes it is more important to stiffen the vertebral column to stabilize the trunk (large ungulates are excellent examples of this).

The structure of the vertebral column and the spinal musculature will depend on the type of gait adopted. There is no ‘typical’ cursorial mammal; there are at least two different types. Thus when Gray (1944) wrote : “In the case of a typical cursorial mammal the propulsive drive is normally controlled by the muscles of the limb, whilst the axial musculature of the back cooperates by providing the body with adequate rigidity ”, he was making a statement which is true of a horse, but untrue of a hare or greyhound.

An excellent account of the anatomy of the vertebral column is given by Slijper (1946). In mammals adopting the leaping gallop the backbone is very flexible, especially for arching in a sagittal plane, and the axial musculature plays an important part in leaping by extending the backbone from its flexure. In mammals adopting the horse gallop the backbone is relatively rigid, although the lumbo-sacral joint may show a certain degree of flexibility, and the axial musculature shows a marked reduction in the fleshy elements .and a better development of the tendinous ones; it is therefore adapted for resisting tension rather than for active contractions.

sci-hub.tw/10.1111/j.1096-3642.1956.tb02220.x

Spinal flexion and extension also occurs in smaller rodents and other carnivores, but is modest or absent in larger ungulates (horses, antelope, wildebeest, etc.) owing to scale constraints of size. A rigid backbone in large ungulates is necessary for effective support of the trunk, which is suspended between the hip and shoulder joints, and the need to transfer load between the fore- and hindlimbs during a gallop.

Reference->

[Dakotaraptor]

Seller et al. (2007) estimated top speed for 6 ton (certainly) adult T. rex of 29 km/h (8 m/s), which is quite reasonable. However if i am not wrong, they didn't include caudofemoralis muscles, which would increase the maximum speed estimates a bit. I think 30-40 km/h for 6-7 ton adults (MOR 555, BHI 3033) is still quite possible.

Ps. I wonder about the Acrocanthosaurus NCSM 14345 femoral length being estimated of 112 cm in recent Persons, Currie's paper rather than 128 cm like in most sources. I don't know... either 128 cm femur was overestimated or they made mistake in paper? Link: www.nature.com/articles/srep19828

Also i am quite suprised about Acrocanthosaurus having more cursorial limb proportions than Allosaurus.

[Infinity Blade]

Elephants are capable of moving at speeds of up to 6.8 meters per second (Hutchinson, 2006). This is not much slower than 8 meters per second proposed by Sellers and Manning and yet dinosaurs like Tyrannosaurus were significantly more adapted for high speed movement than elephants are (I've posted information comparing their respective adaptations for speed, mostly in appendicular anatomy). Therefore, 8 meters a second as a peak speed for Tyrannosaurus is (much) too low in my eyes. I obviously can't say with exact certainty, but I'd personally go with the speeds calculated in Christiansen (2000) as a "reasonable figure range" for the beast.

[Dakotaraptor]

I am really sceptical about Tyrannosaurus being barely faster or as slow as or even slower than elephant too. If the research about cursorial limp proportions is reliable than advanced tyrannosauroids in general probably didn't lose their speed ability compared basal tyrannosauroids*. Futhermore they might be significantly better built for speed. Also if Acrocanthosaurus had really more cursorial legs proportions than Allosaurus, then what about more advanced carcharodontosaurids?

*I mean: advanced vs basal tyrannosauroids, not juvenile vs adult.

[Infinity Blade]

Ceratopsid dinosaurs have traditionally been restored with sprawling forelimbs and were considered unable to run at high speeds. However, recent analyses on forelimb functional anatomy strongly suggest that their limbs operated in a near parasagittal manner, with elbows only moderately averted. As such, the allometric trends of their appendicular anatomy may be compared to those of mammals. The long bones usually scale with similar regression slopes to those of mammals, but in some instances (e.g. forelimb length) the intercept is slightly lower in ceratopsians. Ceratopsians have rather long limbs compared to extant large mammals, such as rhinos, especially hindlimbs, and their forelimbs are not proportionally as short as is usually assumed. Limb proportions indicate that the locomotory potential of ceratopsids could have been comparable to extant tapirs and rhinoceroses. Protoceratopsids appear to have been relatively more agile, which is to be expected from their smaller size alone. Analyses of bone strength confirm the similarity to extant large mediportal to subcursorial mammals, such as large bovids and rhinoceroses, indicating that even large forms were adapted to locomotor performances exceeding those of extant elephants. The running performance of even the largest ceratopsids is restored as significantly exceeding that of elephants, and being broadly similar to that of rhinos.

Christiansen, P.; Paul, G.S. (2001). Limb Bone Scaling, Limb Proportions, and Bone Strength in Neoceratopsian Dinosaurs. Gaia.

[Infinity Blade]

Speed for a sub-adult Edmontosaurus (not sure if the specimen in question counts as giant, I may need to look into the paper more).

"Gait reconstruction of extinct animals requires the integration of palaeontological information obtained from fossils with biological knowledge of the anatomy, physiology and biomechanics of extant animals. Computer simulation provides a methodology for combining multimodal information to produce concrete predictions that can be evaluated and used to assess the likelihood of competing locomotor hypotheses. However, with the advent of much faster supercomputers, such simulations can also explore a wider range of possibilities, allowing the generation of gait hypotheses de novo. In this paper we document the use of an 8000 core computer to produce mechanically and physiologically plausible gaits and trackway patterns for a sub-adult dinosaur (Edmontosaurus annectens), evaluating a large range of locomotor possibilities in terms of running speed. The anatomical reconstruction presented is capable of running and hopping bipedal gaits; trot, pace and single foot symmetrical quadrupedal gaits; and asymmetrical galloping gaits. Surprisingly hopping is the fastest gait (17 ms-1), followed by quadrupedal galloping (16 ms-1) and bipedal running (14 ms-1). Such a hopping gait is considered unlikely for this animal, which would imply that either our anatomical and physiological reconstruction is incorrect or there are important constraints such as skeletal loading and safety factor that are currently not included in our simulation. The most likely errors are in joint ranges of motion, combined with the lengths of muscle fibres and tendons since these values are difficult to reconstruct. Thus the process of gait simulation is able to narrow down our predictions of unknown features of the extinct animal using a functional bracket. Trackway geometries derived from the gait models are currently very basic due to the simplicity of the ground/foot contact model used, but demonstrate the future potential of this technology for interpreting and predicting trackway geometry."

palaeo-electronica.org/2009_3/180/

[Infinity Blade]

Would anyone else like to add their views here (especially on Tyrannosaurus speed)?

[Infinity Blade]

I know some of you know Paleo-King (Nima Sassani), who's on DeviantArt and has his own blog. I've talked with him quite a bit on giant dinosaur (namely Tyrannosaurus) locomotion on the former (namely his profile), just in case anyone's interested.

[theropod]

On Tyrannosaurus (and more generally giant land animal) speed:
The arguments that T. rex couldn’t run don’t really make sense, everything about its limb posture, musculature and physiology say it’s adapted to retain some degree of running ability. However it matters a lot how fast we are talking about.

The 35mph+ from your discussion with Nima are absurdly fast in my view, that’s 56km/h+. Now, even reliable speed figures for extant animals can be hard to get, so I’m not really able to confidently make a concrete comparison here, but that seems like the kind of speed much smaller animals max out at (i.e. modern carnivorans and ungulates, perhaps some ratites too depending on whether the figures I’ve seen are accurate). It may be slower than an ostrich, but think about it, in order to be just as fast as an ostrich T. rex would have to be way more adapted for speed and at the same time also for strength simply considering its size. At this point I doubt that kind of speed is even possible for a terrestrial animal that big.

Referring to the adaptions that it does have doesn’t help the point much either, smaller tyrannosaurs already have those adaptions (i.e. arctometatarsal condition, long distal limb segments, huge tigh muscles) and they didn’t get more pronounced in T. rex, quite the opposite is the case at least in big specimens. Long toes also provide a questionable benefit at best, why don’t we see cursorial animals developing particularly long toes today if they are so useful? In short, I don’t see where exactly tyrannosaurs trump ostriches that much in terms of cursoriality that this would allow a 6 ton Tyrannosaur to run almost as fast as a 60kg ostrich, and even if it did, that doesn’t take into account that at the same time they need weight-bearing ability that will necessarily reduce the effectiveness of those cursorial adaptions.

This is obvious and I don’t think I’m telling anyone anything new here, but the fact of the matter is, an animal’s stride length increases linearly, its strength is squared and its mass is cubed. So an animal can get faster by getting larger as long as it can increase its relative muscle mass and the strength of its skeleton to keep pace with its overall increase in mass and the resulting larger forces acting on it and necessary to move. As long as that’s possible, it can make use of the greater stride length to increase its speed. But you can’t keep up allometrically increasing your muscle mass and bone strength forever, otherwise at some point you’d be composed entirely of bones and muscles making you unable to function as an organism. It’s basically the same reason why there is a limit on the maximum size of terrestrial animals somewhere, albeit a very high one. As soon as musculature and strength cannot increase as much or at all any more it will get slower. So there is such a thing as an optimum size range for cursoriality, and while it’s difficult to pinpoint exactly (I read something about 50kg in some paper once, but obviously there are lots of physiological and anatomical factors to consider as to why the fastest animals may well be slightly above or below that mark) there can be little doubt that T. rex is far above it.
Let’s take a 2t Gorgosaurus and a 6t T. rex. We can all agree that Gorgosaurus has pronounced cursorial adaptions and that many of them are retained by an adult T. rex. But at the same time, if that adult T. rex runs at the same speed it is going to have to produce and withstand 3 times the force of the Gorgosaurus. But unless it disproportionately increases the strength of its bones and joints and the size of its muscles, it will only be able to deal with 2.08 times the force, which would dictate that it would be quite a bit slower. The bones are certainly allometrically thicker, and as for the muscles there’s debate whether they were positively or negatively allometric, which is really a key question in this context and needs more comprehensive studies. But in any case, are the muscles almost 50% larger?
And now, assuming an ostrich is approximately in the optimum size range for running speed, consider making that comparison between it and something 100 times more massive, not 3 times. That’s why I cannot swallow that a giant theropod would be anything but significantly slower than a reasonably cursorial extant ratite.

So yeah, T. rex has fairly impressive cursorial adaptions for its size, there’s little doubt about that, but cursorial adaptions can only get you this far, there are physiological and mechanical limitations on what is possible. I don’t think a 6t animal running as fast as an ostrich is possible at all, regardless of how speed-adapted it is, because some of the adaptions for speed would have to be so extreme they would simply be either physiologically or evolutionarily impossible (like devoting a ridiculous proportion of its body mass to leg muscles–may be possible to some degree, but would never provide a selective advantage and therefore never evolve).
A completely different situation with aquatic organisms, obviously.

30-40kph makes a lot of sense to me, and that’s still quite a bit faster than an elephant, which is a similar-sized but less cursorially adapted animal. Whether it sounds like much of a difference to you or like it’s too insignificant, I cannot decide for you, but in any case I would argue that this comparison makes sense. Comparisons to rhinos and hippos are more complicated, because yes, those animals have short and seemingly small legs, but they are also way smaller than both T. rex and the inevitable Triceratops analogue. So would a Ceratopsian run at least as fast as a rhino of similar size and would a similar-sized tyrannosaur be even faster? Yes, probably. But would a Triceratops, and by inference a T. rex fit into the same scheme even though they are three times as massive as a rhino? And it seems reasonable to assume that at extreme sizes like those of T. rex and elephants, because these animals have to converge on some form of graviportality, speed differences due to differences in cursoriality will get smaller, i.e. the animals are limited in their speed not by how cursorial their limb proportions are, but by how much power they can generate and how much force their bones can withstand.

Note that I have only skimmed the first couple of posts so far, so bear with me in case something I’m writing here was already addressed later on.

[Infinity Blade]

Great post as usual theropod.

Somewhere in my mind I did feel that speeds over ~40 km/h were pushing it quite a bit (despite the last thing I said in post #2), so I guess in that sense I agree with John R. Hutchinson. I can buy 40 km/h. 30 km/h is only* some 3 miles an hour faster than an elephant, which can apparently go up to 6.8 m/s (unless of course, someone can show me that even these are exaggerations). It's still faster than an elephant, so I guess I can still buy it.

Anything equivalent to or less than whatever equal-sized modern elephants reach remains ridiculous IMO. If, at this weight range, it's the power that can be generated and the stress that the bones can withstand that really matters, Tyrannosaurus still seems to fulfill these criteria with its enormous leg, hip, and tail muscles (proboscideans just don't compare in this regard as far as I can tell). As for bone strength, I think the second paragraph of this old post of yours (link) may sum it up adequately (not to mention the shock-absorbing, compacted arctometatarsals universal to tyrannosaurids; elephant metapodials are completely unlike these). Likewise, it seems to me that elephant limb joints (or at least some, like the ankle) aren't very flexible (though obviously not completely immobile), limiting their propulsion ability (this is not the case with flexed-legged tyrannosaurs).

I forgot to ask, though. When Tyrannosaurus ran at max speed, would it still have some sort of suspended phase?

*Or maybe I don't understand just how much faster that really is. If you were to put two cars with drivers in front of me and had one going at the speed of an elephant and one at 30 km/h, then I'd have an idea.

[theropod]

That joint mobility, bone strength and muscle power and moment arms are all vastly superior to elephants would definitely suggest to me that it did still have a suspended phase when running at full speed (hence properly running, and not just fast walking like what elephants do). Might be that moving at 30-40km/h isn’t even metabolically viable without one, but I’m no expert. Obviously Theropod legs have completely different capabilities to elephant legs, I think what you wrote about the joint flexibility might be the key here. Usually legs in a running animal act like a spring, we know Tyrannosaur metatarsals did this and it is one of their most well-known adaptions for speed, but the flexed joints have a similar effect too. Of course with collumnar legs, you lose most of that ability to store elastic energy, which makes a suspended phase in running impractical both because it takes too much muscular effort, and because the shock from impacting the ground can’t be absorbed effectively.

Of course the leg anatomy might just be a leftover feature from smaller, more cursorial subadults. But I tend to think an adult T. rex could run properly, yes. I would expect that the very largest individuals, like sue or other theropods its size, would probably use that ability pretty sparingly if they still had it though, and leave the chases to smaller individuals more often. When we look at that region between 6t theropods and 8t theropods the latter just seem to bulk up a lot and lose much of their legginess.

Completely agreed about the speed.
I consider anything in that range to be plausible. You’re right that 30km/h doesn’t sound like a lot, but compared to 24.5km/h it’s still noticeably faster. As long as it is faster than an elephant at all, I can roll with it, because as I said it’s difficult to say how much efficacy the cursorial adaptions would have at this scale. Perhaps they would really just make it a little bit faster, or perhaps a bit more than that. But I was also rather taking that range as a range for adult T. rex as a whole, so take the 30km/h as referring to a pretty large rex if you want.

[Infinity Blade]

What about Argentinosaurus? There was a publication that concluded it was only mechanically competent at 2 m/s (does that necessarily mean "restricted to 2 m/s"?), but on Carnivora broly made the argument that the study used a very inaccurate skeletal mount.

[theropod]

You mean Sellers et al. 2013?
Sellers WI, Margetts L, Coria RA, Manning PL (2013) March of the Titans: The Locomotor Capabilities of Sauropod Dinosaurs. PLoS ONE 8(10): e78733. doi:10.1371/journal.pone.0078733

The skeleton they used sure is weird, definitely quite far from the current scientific mainstream view of Argentinosaurus’ or other lithostrothian morphology (even as vague as that is).
They just digitized a mounted skeleton, which unfortunately is almost complete conjecture and doesn’t seem to have been constructed with a modern degree of understanding of Titanosaur anatomy. So The limbs belong to an animal that was probably 10m shorter and 10t lighter than they estimated, which would definitely have an impact. Aspects of the limb posture appear pretty strange to me. The ribcage is ridiculously narrow, which might have an influence on some muscle-attachment sites especially on the scapulocoracoid. And the authors themselves concede that they did not include passive support structures, which are immensely important because joints are very very far from being stabilized exclusively by muscle action, which I think is the biggest issue of many.
So really I don’t think much can be said from that. But to be fair, the author’s conclusion is not particularly far-reaching and does not deny that issue either.

We cannot really come up with a speed limit from a simulation that’s so incomplete. The primary thing that paper seems to be doing is proving that a giant sauropod could move at all.

[Deleted]

Yeah, the limbs being forced to support an oversized and anatomically messed-up skeletal frame is probably likely to mess up the speed estimate. By like, a lot, lol.

I bet that an actual ~80+ tonne sauropod with properly-proportioned limbs and real sauropod anatomy would move at a decent speed itself.

[Infinity Blade]

What I don't really understand is how giant theropods supposedly don't have limb shaft strength indicator values any higher than those of animals like elephants or sauropods (see the Encyclopedia of Dinosaurs* and Christiansen (2000) above). In the former source I just mentioned, an 8 ton Tyrannosaurus' femur has a strength indicator of 9 units. A 35 ton Apatosaurus? 6-14 units. A 2.5 ton African elephant cow? 7-11 units.

I understand giant theropods still had relatively long femora for their size (thus limiting their strength), but even then I can't see how they would be about as weak as the limb shafts of the animals mentioned above. We know the largest known Tyrannosaurus (for instance) actually has thicker femora than mammoths that were larger than itself (and
interestingly enough, mammoths had even thicker limb shafts than do modern elephants→), that the bent articulations of theropod hindlimbs would require and make them more resistant to bending stresses (which are incurred during high speed running), and IIRC some of the bones were somewhat curved to reduce bending stresses (like this Tyrannosaurus femur→, or this specimen→). By contrast, elephants and sauropods have columnar legs that don't require as much bending resistance and, to my understanding, even eccentric femoral/humeral cross sections that are much wider (and stronger) mediolaterally than anteroposteriorly. This cross sectional shape is perfect for withstanding compressional and mediolateral stress from your own massive body, but when running, anteroposterior bending stresses will make your limb shafts more likely to snap.

I asked Nima about this earlier too. He mentioned that femur shape (as opposed to raw circumference) is what really matters, that Tyrannosaurus had very strong condyles, and would have had a lot of shock-absorbing cartilage between its joints by modern mammalian standards.

One thing I should note is that I don't know which specimen this "8 ton T. rex" is, and therefore whether or not it would have truly weighed 8 tons (if it weighed less, its strength indicator values should go up). Likewise, the elephant examined was supposed to be significantly smaller than the T. rex (2.5 t vs. 8 t); it's possible a bull elephant weighing as much as a T. rex would have even lower strength indicators.

Anyone else want to weigh in?

*Padian, K.; Currie, P.J. Encyclopedia of Dinosaurs (1997) p. 667. Academic Press. hyperlink