Swimming capabilities of Ankylosauria

[Brocc21]

I thought this would be an interesting topic as I haven't found any papers or articles on it. Does anyone know much of the aquatic capabilities of ankylosaurs and nodosaurs? The only video I've found is by Dinosaur George ( the guy that made Jurassic Fight Club and my childhood hero).  I've seen it suggested the walk across the bottom like hippos or armadillos, and that they would be buoyant enough to slowly float across. Discuss.

[Blade-of-the-Moon]

Like. a. Log.  lol sorry.  I would guess ok in shallow slow moving water.  I've seen art of them in swamps and marshes. Bakker used some in his Raptor Red novel, in a flood they just tucked in and let the water wash them where it may.

[Brocc21]

Like. a. Log.

This is not a bad comparison.

[stargatedalek]

They were probably quite great swimmers, but likely not much of divers. We think of them as heavy animals because of their armor but they are also just very broadly built animals in general which tends to make for strong swimmers that float relatively comfortably. They are also known almost exclusively from water rich habitats, everything from swamps to salt marshes but none of that dry land in between. More of a water buffalo than a hippopotamus.

[Patrx]

I remember reading about a genus of small ankylosaur, Liaoningosaurus, found with fish preserved in its stomach. It's not conclusive, but it could imply a certain degree of swimming ability.

This Tiny Ankylosaur Ate... Fish? (article from Scientific American)

^{Art By Fabrizio De Rossi}

[stargatedalek]

While equally possible (if not more likely) that it scavenged fish washed up on shore, or that the fish became trapped while feeding on the dead ankylosaur, it's still good evidence that they spent a great deal of time in and around water.

[SidB]

Yes, more likely scavenging. probably not the most nimble of fishers.

[austrosaurus]

They were probably quite great swimmers, but likely not much of divers. We think of them as heavy animals because of their armor but they are also just very broadly built animals in general which tends to make for strong swimmers that float relatively comfortably. They are also known almost exclusively from water rich habitats, everything from swamps to salt marshes but none of that dry land in between. More of a water buffalo than a hippopotamus.

I reckon this is a pretty good comparison, animals that were comfortable around slow-moving, shallow water and can swim okay in a pinch, but not doing anything particularly outlandish. I wonder if perhaps during or after floods, smaller animals would have used them as a raft the same way frogs etc. hitch rides on crocodiles. Food for paleoart thought.

[austrosaurus]

I remember reading about a genus of small ankylosaur, Liaoningosaurus, found with fish preserved in its stomach. It's not conclusive, but it could imply a certain degree of swimming ability.

I saw a post on Instagram recently by a guy who proposed a similar lifestyle for Minmi (he also gave it a large nasal boss that has no osteological correlates and also had it being attacked by bald Utahraptors that were the same size as it, so make of that what you will).

[Ravonium]

Could snapping turtles work as an analogue for how ankylosaurs swam? (at least for smaller species)

[Brocc21]

Here's an example:

https://www.youtube.com/watch?v=cW8_M8jfIno

[Killekor]

Wow, I didn't never thought that Ankylosaurs could had been swimmers! This makes them a lot more interesting to me!
In this case I have a question: if they passed part of their day in water, they weren't more vulnerable to prehistoric crocodiles during their swim? Or there weren't where they lived?
I ask this because (correct me if I'm wrong) ankylosaurs were armored in all the body except the belly, and crocodiles could had attacked them from below making them easy preys.

Killekor

[stargatedalek]

Crocodilians don't tend to attack animals many times their own size. All but the smallest ankylosaurs could likely have fended off most crocodiles with kicking alone if one was foolish enough to bother them.

The very large animals like Deinosuchus and Sarcosuchus, in addition to being rare, were heavily focused on attacking aquatic prey.

[CityRaptor]

And to think that older Dinosaur books aften describe them as sinking like rocks.

I remember reading about a genus of small ankylosaur, Liaoningosaurus, found with fish preserved in its stomach. It's not conclusive, but it could imply a certain degree of swimming ability.

This Tiny Ankylosaur Ate... Fish? (article from Scientific American)

^{Art By Fabrizio De Rossi}

Oh yes, this one. Is it weird that I want a toy of this cutie now?

[DinoToyForum]

Liaoningosaurus came to mind immediately to me as well. I think there was also a suggestion that armour plates on its belly were an adaptation to an aquatic lifestyle, protecting it from attack from below?

[Neosodon]

They were probably quite great swimmers, but likely not much of divers. We think of them as heavy animals because of their armor but they are also just very broadly built animals in general which tends to make for strong swimmers that float relatively comfortably. They are also known almost exclusively from water rich habitats, everything from swamps to salt marshes but none of that dry land in between. More of a water buffalo than a hippopotamus.

Saichania is believed to have lived in a dessert environment. There is also a strong preservation bias for aquatic environments so I'm not sure that means Ankylosaurs were an aquatic oriented group. Unless there are strong anatomical indicators of an semi aquatic lifestyle across the family I'd say it's more likely they were generalists.

[Brocc21]

Ankylosaurs are actually occasionally found in fossil beds from the Western Interior Seaway. Having died and sank to the bottom. It's unknown if this is because they were great swimmers and were bouffant enough in life, do to the mass amounts of gas produced in there stomach, to float in water. Or they died, were washed into the sea, and the decomposition bloated their corpses and they floated out to see.

[Loon]

This Tiny Ankylosaur Ate... Fish? (article from Scientific American)

^{Art By Fabrizio De Rossi}

Oh yes, this one. Is it weird that I want a toy of this cutie now?

No, I super want a toy of this guy, aquatic or not. I'm honestly surprised Paleo-Creatures hasn't come out with one.

[Flaffy]

I saw a post on Instagram recently by a guy who proposed a similar lifestyle for Minmi (he also gave it a large nasal boss that has no osteological correlates and also had it being attacked by bald Utahraptors that were the same size as it, so make of that what you will).

A @austrosaurus All creatures in the fan-artwork were based off designs seen in the video game "The Isle", and all depicted behaviours and designs are by no means meant to be scientifically accurate or plausible. The goal was to make a literal walking snack viable in an ecosystem where Allosaurus and Tyrannosaurus coexist.
As for why the "Utahraptor" is the same size as a Minmi, the dossier states that it is a sub-adult.

[Flaffy]

Regarding aquatic ankylosaurs, I've asked around paleo-communities and the general consensus seems to be that they wouldn't be particularly good swimmers per say. But their sheer girth alone would provide adequate buoyancy so that it wouldn't necessarily "sink like a rock".
There have been papers on the buoyancy/floating capabilities of dead ankylosaurs in an attempt to explain how so many ankylosaurs have been found fossilised overturned or in marine paleoenvironments. Here is one that comes to mind: https://www.sciencedirect.com/science/article/pii/S0031018217312452