New Spinosaurus Paper

[suspsy]

It's officially out! This research study concludes that Spinosaurus was most likely not aquatic and did not dive or swim after its prey like an otter or a seal. However, it still would have lived in and around water, and fed primarily on fish and other aquatic life.

And in terms of size, the study finds that an adult Spinosaurus achieved achieved about 14 metres in length and 7400 kg(7.4 US tons) in mass. By comparison, Giganotosaurus and Tyrannosaurus rex both achieved up to 13 metres in length and 8.5 tons and 9.8 tons in mass respectively. So while Spinosaurus was indeed the longest theropod, it was *not* the heaviest or the most powerful.

https://elifesciences.org/articles/80092?fbclid=IwAR1Fd6J8rEQ0O_8bjaVjwzQg-wSgTH8UeYPpqna8tH0Q-aI4DxWf7u8PVG0

[bmathison1972]

I always envisioned Spinosaurus living around water, wading and maybe paddling in deeper waters, with the ability to catch fish within a few meters of the surface of the water. But I never really envisioned it as a diver (like a grebe, penguin, or seal); but I am not and never had been an expert on this group. My Safari 2019 model is still technically outdated but I am not replacing it for now

[Faelrin]

The new sail reconstruction is interesting, and quite different from the iterations before. Looks more like the classic interpretation, like on older toys and such.

Glad the paper is open access, and not behind a paywall, especially something this rigorous as it appears. Based on the material used in the new reconstruction, it may be safe to say that Spinosaurus is not as fragmentary as it seemed. Incomplete still (especially as the forelimbs and a portion of the spine goes), but nowhere near as scant in prior years.




I'll have to give this a read later, maybe tonight even.

[Remko]

I'm reading this now.
Very interesting article, and Sereno makes a strong case for a non-aquatic lifestyle.

Basically the article comes down to this: Spinosaurus couldn't dive, or even swim upright. Body density was less than that of water (salt or sweet), so it would have floated awkwardly. The sail isn't helping either. And the hindlimbs weren't much use for swimming either, in fact, they had more drag than the hindlimbs of Tyrannosaurus or Carcharodontosaurus.

The tail doesn't resemble anyhting we know with an aquatic lifestyle either, and was probably for display.

I'm looking forward to how this discussion among both the scientific world, and the public will evolve in the comming years.

[suspsy]

Here's a summary of the findings, along with some nice artwork by James Gurney:

https://biologicalsciences.uchicago.edu/news/features/spinosaurus-not-aquatic?fbclid=IwAR1nd0ELdMCPYql4pptxjBm1ACRZMi0cOSZC-fREz6EnxnKdXD1NedH4CsI

[Pliosaurking]

It's always interesting to see how are understanding of Spinosaurus changes. That paper does make a good argument against an aquatic lifestyle, I always envisioned Spinosaurus as semi aquatic but not a full blown diver which this paper explains very well.

[andrewsaurus rex]

An interesting niche for a large predator.  I wouldn't have thought it would get enough food along a shoreline to sustain itself.

Also interesting is S. tenerensis, which i hadn't heard of.   The lack of any dorsal sail is very curious.  What happened over a 15 million year period that caused S. aegyptiacus to develop its large sail?

[Blade-of-the-Moon]

I recall in reading Bakker's Raptor Red he painted a shoreline as a buffet area for scavengers and hunters alike.

[dinofelid]

Also interesting is S. tenerensis, which i hadn't heard of.   The lack of any dorsal sail is very curious.  What happened over a 15 million year period that caused S. aegyptiacus to develop its large sail?

They refer to Suchomimus tenerensis as an "older related species", not an ancestor, so it wouldn't tell us how long Spinosaurus took to evolve its sail. That said, if the sail was primarily about some kind of sexual or social signaling rather than some non-social function, I wonder if those kinds of features (like peacock tails or dramatic crests on hadrosaurs, frills and horns on ceratopsians etc.) have a tendency to evolve more quickly due to some kind of feedback loop where once the species develops a preference for that differentiating feature, then the more exaggerated, the more successful the individual with the exaggerated variant, at least up until some limit where it gets too unwieldy.

[Remko]

After reading the entire article, the conclusion is that Spinosaurus was a semi-amphibious ambush predator. It makes sense.

But I've got questions. If it preyed on fish, it would have preferred larger species, and there were plenty in its environment. But the article also states, it would have been able to walk only in water that's about 2,6 meters deep.

For the giant coelacanths, lungfish and sawfish around there, that would have been very shallow. If you compare Spinosaurus to similar fish stalking birds today (herons and storks) they all have very long legs. Not short stubby legs.

As an ambush predator on land, it would be very slow, unless it preyed on slow and small animals.

Perhaps it would lay in the shallows and wait for the unsuspecting dinosaur coming in for a drink. But it wouldn't have been as fast as a croc (nevermind its inability to stay submerged). And the billboard sail wouldn't help hide it either.

I have a feeling there's much to learn about Spinosaurus, and this paper is far from the definitive work on this incredible animal.

[andrewsaurus rex]

I can't see it being any kind of an ambush predator on land, not with that huge sail on it's back, unless the sail was incredibly well camouflaged.

and I've had exactly the same reservations about it in the water......it would only be able to get small fish from the shallows, hardly enough for a 45 foot predator.   Not to mention it would be difficult for such a large animal to catch small, quick moving fish...it would burn a lot of energy in the attempt.  And  since deep water swimming seems to be out of the question......how did it get enough to eat?

[Gwangi]

I think people here are assuming that shallow water means small fish and that's not really how it goes. 2.6 meters of water is plenty deep enough to hold large fish, especially fish like sawfish and lungfish which still live in shallow water habitats in modern times. It's a requirement for lungfish, for obvious reasons. And with tidal flats, mangrove forests, marshes, estuaries, you can get vast amounts of shallow water.

We know what kind of fishes lived alongside Spinosaurus and most of them would not appear out of place in shallow water. In fact, the biggest fish appear to be those most adapted to shallow water.



I hate to share an image from the Pterosaur Heresies but...



So yeah, I find it easy to envision Spinosaurus chilling in some shallow water, standing there waiting for a fish to swim close enough to its arms. And maybe the short legs are an adaptation to bring the arms closer to the bottom because Spinosaurus is hunting shallow water, bottom dwelling fishes. The paper does state that Spinosaurus has adaptations in the hands for grabbing prey. A heron is probably not a good Spinosaurus analogy, it's not hunting with its hands.

[suspsy]

Yeah, where are some people getting the bizarre notion that 2.6 metres is somehow too shallow for large fish to swim in? Have any of you ever actually been in water that deep?

[bmathison1972]

I think people here are assuming that shallow water means small fish and that's not really how it goes. 2.6 meters of water is plenty deep enough to hold large fish, especially fish like sawfish and lungfish which still live in shallow water habitats in modern times. It's a requirement for lungfish, for obvious reasons. And with tidal flats, mangrove forests, marshes, estuaries, you can get vast amounts of shallow water.

We know what kind of fishes lived alongside Spinosaurus and most of them would not appear out of place in shallow water. In fact, the biggest fish appear to be those most adapted to shallow water.



I hate to share an image from the Pterosaur Heresies but...



So yeah, I find it easy to envision Spinosaurus chilling in some shallow water, standing there waiting for a fish to swim close enough to its arms. And maybe the short legs are an adaptation to bring the arms closer to the bottom because Spinosaurus is hunting shallow water, bottom dwelling fishes. The paper does state that Spinosaurus has adaptations in the hands for grabbing prey. A heron is probably not a good Spinosaurus analogy, it's not hunting with its hands.

perfect, this is exactly how I always envisioned Spinosaurus, at least since the aquatic connection became more mainstream

Yeah, where are some people getting the bizarre notion that 2.6 metres is somehow too shallow for large fish to swim in? Have any of you ever actually been in water that deep?

And I have been in 2.6 meter water many times (kinda a requirement for competitive triathlon LOL)

[andrewsaurus rex]

sure I've been in 8 foot deep water.  All the time when I was a kid up north, fishing with my dad...more than 8 feet deep most of the time.  The water was full of perch, bass, sunfish, trout, catfish, some pike...all fairly small fish.  Ok for the bbq for supper that night but not really big enough for a 45 foot Spinosaurus to eat.     

Mind you I haven't been in 8 feet of water in every locality on earth and from every time period in earth's history, so I wouldn't have known about all the large fish living in shallow water.  I guess not everyone has your worldly experience, suspsy. 

That's an interesting picture from Pterosaur Heresies....it brings home the environment much more clearly.  BTW what is wrong with Pterosaur Heresies?

[suspsy]

sure I've been in 8 foot deep water.  All the time when I was a kid up north, fishing with my dad...more than 8 feet deep most of the time.  The water was full of perch, bass, sunfish, trout, catfish, some pike...all fairly small fish.  Ok for the bbq for supper that night but not really big enough for a 45 foot Spinosaurus to eat.

Every single animal in the first image that @Gwangi posted is known to have coexisted with Spinosaurus. Your own personal experience in a totally different environment on a totally different continent at a totally different time does not constitute an argument at all.

Mind you I haven't been in 8 feet of water in every locality on earth and from every time period in earth's history, so I wouldn't have known about all the large fish living in shallow water.  I guess not everyone has your worldly experience, suspsy. 

Is there really any need for such a tone?

[GiganotosaurusFan]

No arguments here, we're all chill right(I'm sorry, I feel tension going on)?
Ok, I agree with some points. Maybe 2.6 isn't really a realistic number, but really, there is also a chance that Spinosaurus was faster than thought.
For example, some really big and tall but lanky people can actually run quite fast, and wade well. That's just my hypothesis.

[andrewsaurus rex]

Yeah, where are some people getting the bizarre notion that 2.6 metres is somehow too shallow for large fish to swim in? Have any of you ever actually been in water that deep?

suspsy.....if you're going to make comments like that, you have to expect people are going to take exception to it.  I could say more, but this is my last word on the subject.  No need to bicker in public...nobody wants to read it.  Happy to continue in pm if you like.

[suspsy]

Yeah, where are some people getting the bizarre notion that 2.6 metres is somehow too shallow for large fish to swim in? Have any of you ever actually been in water that deep?

suspsy.....if you're going to make comments like that, you have to expect people are going to take exception to it.  I could say more, but this is my last word on the subject.  No need to bicker in public...nobody wants to read it.  Happy to continue in pm if you like.

Take exception to what exactly? The fact that 2.6 metres of water is enough to accommodate any of the prehistoric fish shown in the diagram above? Modern arapaima grow up to 200 kg and three metres in length and they regularly inhabit rivers that are even shallower than that. Please don't get offended just because I refuted your argument.

[dinofelid]

That's an interesting picture from Pterosaur Heresies....it brings home the environment much more clearly.  BTW what is wrong with Pterosaur Heresies?

I don't think there's anything wrong with that picture specifically, but for general problems with Pterosaur Heresies see this post from Darren Naish.