One of the first videos to get really big on
this channel was my first video about Spinosaurus and that's because Spinosaurus is really good at
being in the news Honestly, it's probably too good at being in the news considering just how partial it is But regardless of all that, it's in the news again and largely again due to the same reasons as before and that's What was its lifestyle? And all of this really started in 2014
with a paper by Ibrahim et al which suggested, based on a new specimen of Spinosaurus, that Spinosaurus would have been primarily aquatic It would have swam through the water pretty quickly after prey and caught fish swimming away And there's been a lot of discussion about this since then even in scientific literature And that can take years sometimes... But that just means that since then, in 2014 there's some papers that have said 'no, it's not aquatic!' and then paper saying 'no, it is aquatic!'
and then 'no, it's not aquatic!' and then 'yes, it is aquatic!' And then in 2021 there's a paper by Hone
and Holtz so it's pretty rounded out that actually said no it's not aquatic
and here's a list of reasons why And this is the one that actually I did the video on
that did pretty well So if you want that information in that background,
you can check that out But since then again there's been more papers that say
'no, it is aquatic!' such as one earlier this year that looked
at the density of the bones and said yeah based on the density,
it is more like animals that would be swimming Specifically, secondarily aquatic tetrapods So these are just animals with four limbs and a
backbone that live on land that then moved back to the water So whales, mosasaurs, otters, but also even things like Spinosaurus... potentially It did have dense bones,
and we'll get more to that here in a moment And the reason we're getting to it here in a moment is because first I just want to show you the title of this newest paper that says it is not an aquatic dinosaur Like quite literally, the title is just
'Spinosaurus was not an aquatic dinosaur' They are not trying to beat around the bush here They are being very direct in what their ideas are
and what their conclusions are And they have a lot of reasons for this And essentially they break down the aquatic
hypothesis into three separate sections The first idea is that it would be quadrupedal
when on land Essentially, because it was so adapted to the water it would have needed to walk on all fours unlike any other theropod dinosaur And so theropod dinosaurs are everything from little Velociraptors up to giant Tyrannosaurus Rex And so again all those are just walking around on two legs it would be really weird for Spinosaurus to have changed But if it was doing that it's good evidence that
yeah maybe it was more aquatic The second step is taking on a 2020 paper by Ibrahim et al Which found that it had a more paddle-like tail that would have been great for trying to propel itself while I was actually swimming And they addressed that issue as well as a few others that had to do with the tail And the final idea has to do with large tetrapods that actually moved back to the water And when we're thinking about that we need to think of things over 30 feet so again really large animals like whales and mosasaurs Which have only been found in coastal sediments
and in marine sediments So unless we're only finding Spinosaurus
in those kinds of environments it's pretty safe to say it may not have been swimming as much I do want to be clear here before I go
straight into their arguments because they do take specific care
to define what an aquatic animal is and an aquatic animal is something that has adaptations specifically for water to a dramatic degree So essentially, it's almost functionless on land. So like otters- Otters are semi-aquatic because
they still get around on land pretty well So are many freshwater turtles
they still get around on land Sea turtles really struggle on land because they're really not designed to actually have their flippers support them and move them across the land very easily And so, in order to test many of these ideas, the authors set about making a model And this isn't a real life model, but it is a pretty good
3D model in a computer And this is different than what was done in the 2020
paper with the paddle-like tail which used a 2D model just to try and guess
what the propulsion of that tail might be This paper actually looked at what kind of muscle mass would have been there to try and understand that kind of propulsion And so let's get into what this 3D model says first by looking at how well it would have actually done on land So there's two marks on this model The one that's more forward is actually the center of buoyancy meaning when it's in the water,
that's the point it would pivot around But the center of gravity is different because lungs don't provide the same kind of buoyancy in air as they do in the water Which means the center of gravity would actually be like most other theropods, pretty much right over the hip bones Meaning it wouldn't really need its forelimbs
to actually be able to walk around So it's a really good piece of evidence that, no it wasn't doing this super specialized quadrupedal knuckle walking Instead, it was walking around like pretty much
any other theropod dinosaur And then moving on to that buoyancy point, it doesn't seem that important when
you're looking at it from the side Because like, okay yeah, that still kind of towards the middle of the animal... It could probably manage And it probably could manage to some degree The thing is, as soon as it tilted over
it would struggle to get back up This graph shows the amount of torque, or essentially rotational force, it would need if the sail actually ended up at a specific angle So essentially, as it rotates, you can see how much
energy the animal needs to try and right itself upright There's also one graph that looks at how
much drag the sail would have actually caused and a lot of people have actually compared this, online at least, to the sail in a sailfish which goes really really fast In fact, it's one of the fastest fish there is, if not THE fastest The thing is the sailfish though, when it's swimming really fast, it could actually retract its sail into
a flap of skin on the top of the body Spinosaurus just couldn't do this. It did not have a kind of folding sail instead it was very rigid Meaning no matter where this animal was swimming
it would cause drag And one of the authors on this, Frank Fish,
(relevant name for water mechanics) was able to show that animals actually experience more drag near the surface of the water And because of the size of the sail
in the animals like Spinosaurus, it would have actually needed to get as far as 10 meters in depth to avoid any kind of drag interactions with the surface And that I will get to later, but you can see
from the first part of the graph where the yellow thrust line intersects with those drag graphs Those are essentially going to be the best
amounts of speed that this animal can swim So under the water, it could potentially reach as high
as 1.4 meters per second The thing is, that's not very fast... and that's even under the best conditions more realistically when you're including the drag from the tail because only some of the tail propulsion is actually going to move into forward movement it was probably moving about 1.2 meters per second And we can compare this speed to the speed of Michael Phelps And let's be real, Michael Phelps while fast could not catch a fish Spinosaurus could not catch Michael Phelps So it really wasn't going that fast and we can really see that we can compare it to, not Michael Phelps, but other predatory swimming animals Now when we think about fast pursuit predators,
they're all going about 20 meters per second And this is things like Mako, or Tuna,
or again like I mentioned sailfish These fish are really really fast and it doesn't really make sense for something like Spinosaurus to be behaving in the same way,
because it just could not reach those speeds In fact, it seems like the sail would have
increased drag by about 33% It's a massive amount of weight to carry around that's also going to just cause extra drag moving through the water So it really wasn't some adaptation for swimming, and in fact would have been actively detrimental for swimming It would have been so detrimental in fact that it probably couldn't actually swim at 10 meters depth When they did the calculations with how much buoyancy Spinosaurus would have had how much force would be lifting it
to the top of the surface of the water They actually found that it would take more power
than that tail could actually generate So essentially, it would be permanently stuck
trying to swim down and making no progress It's really really not likely that it was swimming
underwater going after prey based on this. It's just the mechanics of the organism do not work in that way, at least based on this model And speaking of that model, they did find some differences
with the Ibrahim 2020 model Specifically, that it probably was about a meter shorter which isn't a ton, but it is a decent amount considering this is probably a sub-adult individual that we have these new fossils of And it is still important to note that this model
may not be totally correct In fact, all models are in some ways incorrect it's just some models are useful for telling us things And based on what we know of the animal's physiology,
this one is the most correct And one of the important things they do with that buoyancy is showing how it would have shifted forward
because of the lungs In large diving animals today, like whales, they can actually compress their chest and their lungs and that makes their lungs more dense which makes it easier for them to sink in the water Spinosaurus had a very rigid torso, it could not necessarily compress its lungs in the same way So it wouldn't be able to actually make those lungs more dense And that comparison to whales brings up
the question where do we find them? Do we find them in Marine and Coastal sediments like we do with whales, or with mosasaurs, or plesiosaurs? Sometimes, sure But specifically still only in coastal environments And this is across a broad swath of spinosaurs
including things like Baryonyx, the many species from Spain,
as well as some from South America The thing is though, we've also found them
inland in River environments Meaning that they're not near a coast and this is especially true of some new material of Spinosaurus that some of the authors found coming from Niger and Algeria And these ones were distinctly inland-
they were very much in river environments And again, this is all attributable to the same genus Spinosaurus Meaning it's not some other Spinosaurus that's inland,
it is Spinosaurus that is also inland So it's really looking pretty weak for for the idea that
this thing was actually out swimming as a pursuit predator And so really these authors are just trying to address the idea that it was aquatic and they do run a few more tests they look at things like the feet of Spinosaurids and compare them to the feet of modern day semi-aquatic and aquatic tetrapods So like crocodilians, but also things with proper flippers And their conclusions are, yeah it really wasn't swimming in the water. Not that it couldn't swim But that that's not its primary mode of life It was instead probably living somewhat like a heron does Hanging around the edges of waterways, including coasts where even I've seen herons And then striking quickly at fish or potentially even small crocodilians and eating those as its main source of prey Additionally, it could have also moved on land
and hunted things on land too I mean, I've seen herons hunt things like gophers and certainly a gopher would be too small for a Spinosaurus but there may be prey out there that we just haven't found yet that Spinosaurus would be able to feed on on land as well And so that's it for Spinosaurus, for now at least... I'm sure it'll get back into the news because it
always ends up coming back to Spinosaurus and I've also seen some tweets by some of the other authors on some of those more aquatic papers saying that they had some issues and concerns about this paper And this just means they generally still think
that it was probably more aquatic And that means they're going to try and find evidence for that, and the other authors are going to try
and find evidence against that and it's going to go back and forth and back and forth until we have a really really good body of data for Spinosaurus Problem is... it's just sometimes it's so exhausting
waiting for all that data to come out
