Spinosaurus Wasn't Aquatic New Theory Suggests

[IrritatorRaji]

EDIT: For those wanting something more extensive, here's Henderson's paper on it which includes many more dinosaur and animal comparisons
https://peerj.com/articles/5409/





https://canoe.com/news/local-news/royal-tyrrell-research-blows-swimming-dinosaur-theory-out-of-the-water/wcm/da6cae8d-5a2c-4da2-b86d-03edde6edecf

Some snippets

"using different techniques that relied on physics-based testing methods, the Royal Tyrrell Museum's curator of dinosaurs, Donald Henderson, found that the 95-million-year-old species would not have been able to survive living in water.

Henderson created three-dimensional, digital models of Spinosaurus and other predatory dinosaurs in order to test their centres of mass buoyancy and equilibrium when immersed in water. He also tested the software using models of semi-aquatic animals such as an alligator and emperor penguin, for comparison."


"Henderson's models showed that Spinosaurus could float with its head above water. However, models of other dinosaurs demonstrated similar results."


"His models showed the Spinosaurus would have been able to float with its head above water and breath freely, just like other dinosaurs analyzed in the study.

But unlike semi-aquatic animals like alligators, which can easily self-right themselves when tipped to the side in water, the Spinosaurus rolled over onto its side when tipped slightly."

"Its centre of mass was also found to be close to its hips, between its hind legs, as opposed to the centre of the torso, which had been proposed by Ibrahim's 2014 research."


" "The combination of mass close to the hips, an inability to sink underwater, and a tendency to roll onto its side unless constantly resisted by limb use, suggest that Spinosaurus was not specialized for a semi-aquatic mode of life," the researchers stated."

The entire article is an interesting read, still not sure what to make of it yet. What are your thoughts?

[stargatedalek]

No mention of it's thickened bones, the neural structure in their simulation is practically 2D, and they use a dated reconstruction of Spinosaurus gastralia which has led to it being too narrow (Spinosaurus should be wider), I don't think there is much to be learned here...

[Sim]

The part of the news article that says it's suggested "that Spinosaurus was not specialized for a semi-aquatic mode of life" is misleading if viewed separately from the next thing the news article says, which is: "Spinosaurus may have been specialized for a shoreline or shallow water mode of life, but it would have still have been a competent terrestrial animal," added Henderson.

To me it appears the paper is suggesting that Spinosaurus wasn't specialised for swimming or floating, but that it would have still been a semi-aquatic animal in other ways.  These quotes are from the paper:

Despite the above problems with having Spinosaurus as an animal that spent substantial amounts of time immersed in water, it is still reasonable to interpret the animal as having some connection with aquatic environments. Charig & Milner (1997) noted the gharial-like aspects of the skull and dentition of another well-known spinosaurid, B. walkeri, and proposed that Baryonyx was wading in the shallows snatching fish with its specialized jaws. The very robust arms and manual claws of Baryonyx were also suggested as another way for the animal to procure aquatic prey without having to become fully immersed—similar to modern grizzly bears (Charig & Milner, 1997). Amiot et al. (2010) used stable isotope geochemistry analysis of oxygen in the teeth of spinosaurids to show that they must have spent significant time in water and must have included some aquatically derived prey as part of a more generalist diet. Ibrahim et al. (2014) made a series of observations of the skull and teeth of Spinosaurus that suggested it was well adapted to sense, pursue, and capture aquatic prey. However, given the findings of the present study, the more conservative, and more terrestrially linked, Baryonyx model of Charig and Milner would also seem to be the one for the interpretation of the mode of life of S. aegyptiacus.

The conclusion is that Spinosaurus may have been specialized for a shoreline or shallow water mode of life, but would still have been a competent terrestrial animal.

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No mention of it's thickened bones, the neural structure in their simulation is practically 2D, and they use a dated reconstruction of Spinosaurus gastralia which has led to it being too narrow (Spinosaurus should be wider), I don't think there is much to be learned here...

I'm not seeing the problems you mentioned..  By thickened bones, do you mean denser bones?  The paper does cover the denser bones.

[Lizerd]

I am in doubt of this, for one that torso looks pretty thin. We also have adaptations that would suggest it was fully aquatic, dense bones that were not hollow, barrel-shaped torso, shortened legs, etc. Or maybe I'm wrong, I have 0 qualifications for this 

[ITdactyl]

I like that a counterpoint has been published, but tend not to favor any one argument.  This is probably just one jab in what will likely be a decades long fencing match, so to speak.

However, since stargatedalek mentioned it - I never realized Spinosaurus' silhouette viewed from the top would be that slim.

[Lizerd]

My guess is that it was just something that was assumed on a skinny model, but then again, none of us have qualifications  for this

[Dinoguy2]

I like that a counterpoint has been published, but tend not to favor any one argument.  This is probably just one jab in what will likely be a decades long fencing match, so to speak.

However, since stargatedalek mentioned it - I never realized Spinosaurus' silhouette viewed from the top would be that slim.

It's not. In fact some paleontologists on Facebook are criticizing the paper for this reason. The rib cage of Spinosaurus is actually unusually wide and tube-shaped for a theropod. According to the paper itself, Henderson did not look at Spinosaurus bones to make the reconstruction. He looked at Greg Paul skeletals of Allosaurus and other theropods. Which in my opinion completely invalidates the entire paper. It is not logically possible to test if Spinosaurus had different buoyancy from other theropods by using the measurements of other theropods as your data! I'm not trying to call Henderson stupid or anything but that's a pretty fundamental science fail and I'm really struggling to come up with some explanation of how that happened and got through peer review.

[Sim]

I don't notice a difference between the width of Spinosaurus in the dorsal view from the new study, and "official" reconstructions based on the 2014 version such as the large skeleton in a swimming pose and the large model with the fish, among other points of comparison.  It could be that there is a difference though and I'm just not seeing it?  What source shows a wider Spinosaurus?

[Lizerd]

@Sim the skeleton is my guess
(this might be big)

Notice the torso is round, far more round that that of say a T.rex, similar to that of say a dolphin or most sea-going creatures. It suggests at least a semi-aquatic lifestyle, to a degree.

[Sim]

@Lizerd:

That skeleton is one of the things I compared the dorsal view in the paper to, and I don't see a difference.  I've also used the views of it shown in this video as a comparison point, and I don't notice a width difference: https://www.youtube.com/watch?v=S5Pf49nCdio

Spinosaurus does seem to have a rounded torso, but the torso of Tyrannosaurus to me looks just as round if not more round.  The torso of Tyrannosaurus looks like a barrel!

[Lizerd]

Actually I should correct my self before madly bashing my head into the key board:
The whole body of spinosaurus is rounded, like say an orca or a whale
(Random off topic thing but its really cool: orcas are called killer whales because: they kill whales, no joke. ok back on topic)
a t.rex chest looks like a barrel, but the whole body doesn't, so a spinosaurus would have a body type similar to an orca, but with arms and legs. Or again, maybe I am all wrong

[stargatedalek]

Viewed from the front Spinosaurus body should resemble a (very) smoothed rectangle, more like crocodilians, hippos, or even turtles than the traditional vertically flattened theropod form.

This papers strict adherence to the Ibrahim reconstruction in every minutia is actually a large part of its failings too. Since that paper not only have more remains been found* but numerous aspects of the Ibrahim reconstruction have been questioned, some more definitively than others, and none of these alternative reconstructions were even considered in this analyses.

*Yes MHNM.KK374 to MHNM.KK378 are incredibly fragmentary, but they do hold serious implications for either variation or growth patterns.

[Lizerd]

If it is allright and you have the time, can we see some of the new fossils as well as the reconstructions around them? It could help explain a lot of what is wrong about the paper.

[Huskies]

Just out of curiosity, how are the spinosaurus rib bones compared to the other species in the same family (such as baryonix, suchomimus, etc.).

[Lizerd]

I wish I knew, but I really don't. My guess is that they would be thicker and more rounded? I say go and research it! For science!

[Dinoguy2]

I don't notice a difference between the width of Spinosaurus in the dorsal view from the new study, and "official" reconstructions based on the 2014 version such as the large skeleton in a swimming pose and the large model with the fish, among other points of comparison.  It could be that there is a difference though and I'm just not seeing it?  What source shows a wider Spinosaurus?

I think they were using Stromer's photos. I'm not sure how to repost stuff from FB here but I believe it was Andrea Cau who posted the comparison? Or somebody in one of his threads. He also mentioned using the Ibrahim reconstruction as a basis for the measurements is inappropriate because it's heavily composited and a lot of the relative proportions are speculative and may be off compared to scaling from individual specimens.

In other words, was this paper a test of whether Spinosaurus was aquatic, or whether Ibrahim's specific reconstruction of Spinosaurus was aquatic? Those are VERY different questions.

[Sim]

In other words, was this paper a test of whether Spinosaurus was aquatic, or whether Ibrahim's specific reconstruction of Spinosaurus was aquatic? Those are VERY different questions.

That's true.  I agree.  I wonder if the paper didn't distinguish between those two things at times.  I think the paper was definitely testing how aquatic Ibrahim's reconstruction of Spinosaurus could be, based on for example this quote from the paper:

The new restoration of Spinosaurus by Ibrahim et al. (2014) is a composite derived from several specimens, and there will always be a level of uncertainty as to the actual dimensions and relative proportions of the various body regions. As the claims for a semi-aquatic mode of life for Spinosaurus were associated with this new restoration, it was the one used for model generation and buoyancy/stability testing.

I'm not sure it's possible to test how aquatic Spinosaurus could be due to how incomplete its remains are.  Unless more remains are found that give a good idea of what the complete skeleton of Spinosaurus is like, I think it will probably continue to be a matter of testing and thinking about specific reconstructions of Spinosaurus.


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I did some more comparing last night and I think I do now see a width difference in this paper's model.  It seems to me the torso of Spinosaurus would've been a bit wider in the area in front of the legs.

[Doug Watson]

I'm not sure it's possible to test how aquatic Spinosaurus could be due to how incomplete its remains are.  Unless more remains are found that give a good idea of what the complete skeleton of Spinosaurus is like, I think it will probably continue to be a matter of testing and thinking about specific reconstructions of Spinosaurus.
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I did some more comparing last night and I think I do now see a width difference in this paper's model.  It seems to me the torso of Spinosaurus would've been a bit wider in the area in front of the legs.

I found this on the Nat Geo website where Ibrahim, Holtz and Hone weigh in on the paper. Ibrahim points out more Spinosaurus bones have been found and are being formally described. Also I have to admit his point that Henderson did not work off of the actual bones is compelling.

P.S. As someone who spends a lot of time trying to get bipedal dinosaurs to balance on two legs I would like to see someone build an accurate (unweighted) model and have it stand on its own before I believe the paper on the center of balance. To my eye it still looks like it will take a nose dive.

From National Geographic web site
Life Aquatic
In a phone interview on Thursday, Ibrahim welcomed Henderson's study, but he also expressed some concerns.

For one, he says that Henderson didn't ground-truth his models with the bones themselves, a collection which Ibrahim co-curates. He adds that, like all of paleontology, computer modeling of ancient animals faces its own sources of error. Future models will benefit from more fossils; Ibrahim says that additional Spinosaurus bones have been found and are being formally described.

"It's always good to use modeling techniques, but we need more of this, and we need more modeling that's actually based on the fossils," he says. "At the end of the day, the truth lies in the bones, not in a computer."

Holtz adds that Spinosaurus may well have been in the early stages of evolving its semiaquatic lifestyle. "You don't necessarily have the equipment you want to do the behavior when you start doing that behavior," he says. These adaptations develop over time.

For his part, Henderson imagines the animal like a grizzly bear: a fish-eating machine that would have had no problem walking into and out of the shallows.

David Hone, a paleontologist at Queen Mary University of London, adds that swimming is by no means the litmus test for a life aquatic.

"Herons aren't very good at swimming, but they spend most of their time knee-deep in water, wading around the edge of rivers," he says. " 'Semiaquatic' might be a push, but you're definitely talking about an animal whose ecology is fundamentally linked to water."

[suspsy]

Adult hippos cannot swim at all, yet they spend most of their time immersed in water.

[Lizerd]

Adult hippos cannot swim at all, yet they spend most of their time immersed in water.

Off topic fun fact about that: they sort of moon walk, bouncing up and down.
Back on topic: my guess is even if, EVEN IF, spino could not swim, it could moon walk like a hippo would, bouncing up and down (and being the stuff of nightmares).