Spinosaurus new look!

[Blade-of-the-Moon]

Forgive me if I'm mistaken, but isn't Hartman's reasoning dependent on whether you agree with him about the limb proportions?
The point about the acetabulum does throw a wrench in the loon idea though.

But... wouldn't all this also be dependent on how aquatic Spinosaurus was?

I'm thinking more loon-like in the water, on land I honestly don't know..if the limbs are as reported then I doubt it came on land very often at all except when it had to.

Now if the back legs are longer then the problem is moot as you said.

Spinosaurus for all the bluster seems to me a fragile animal.  The jaws are thin, the sail/spine prevents it from rolling over on land, and it's big too. making every issue it has to deal with that much harder.  It's living in a complicated eco-system as well, something goes wrong in it and things fail everywhere.

[Kovu]

I'm thinking more loon-like in the water, on land I honestly don't know..if the limbs are as reported then I doubt it came on land very often at all except when it had to.

Now if the back legs are longer then the problem is moot as you said.

Spinosaurus for all the bluster seems to me a fragile animal.  The jaws are thin, the sail/spine prevents it from rolling over on land, and it's big too. making every issue it has to deal with that much harder.  It's living in a complicated eco-system as well, something goes wrong in it and things fail everywhere.

I'm more inclined to believe the published proportions in Ibrahim et al as I personally feel that measurements from the actual fossils should trump measurements from pictures, which would lead to the assumption of a largely aquatic lifestyle. Coupled with the histology/isotope analysis and the bone's densities, I think we are looking at a largely aquatic animal. And if that's the case, its terrestrial locomotion being awkward and clumsy is more believable since its not using it that much.

Just from my layman's understanding obviously.

[Simon]

I'm more inclined to believe the published proportions in Ibrahim et al as I personally feel that measurements from the actual fossils should trump measurements from pictures, which would lead to the assumption of a largely aquatic lifestyle. Coupled with the histology/isotope analysis and the bone's densities, I think we are looking at a largely aquatic animal. And if that's the case, its terrestrial locomotion being awkward and clumsy is more believable since its not using it that much.

Just from my layman's understanding obviously.

I agree with your analysis about it being a largely aquatic animal

I still think that the proportions of the legs as reconstructed by Ibrahim, et al, are most likely incorrect and stretch the bounds of credulity.

[Blade-of-the-Moon]

Same here bud, I just read what's written and form an opinion based on it. Just like many others.

I trust Scott quite a bit but it does seem they did a fair amount of research before releasing anything. I'm pretty conflicted there.  Anyone who does the research and puts in the time deserves respect.

[Kovu]

Same here bud, I just read what's written and form an opinion based on it. Just like many others.

I trust Scott quite a bit but it does seem they did a fair amount of research before releasing anything. I'm pretty conflicted there.  Anyone who does the research and puts in the time deserves respect.

Haha, that's all we really can do, right?

Ibrahim and some of the other authors respond to Scott's new proportions. I agree with you bro, I have mad respect for him, but in this case, I agree with the original authors. I was on the fence for a bit, but after reading their response, yeah. Taking osteological measurements from anything but the actual bone, I feel like the margin for error is too great.

Here's the link the response btw, sorry if its already been posted.
http://www.skeletaldrawing.com/home/aquatic-spinosaurus-the-authors-responsd9182014

[Yutyrannus]

Same here bud, I just read what's written and form an opinion based on it. Just like many others.

I trust Scott quite a bit but it does seem they did a fair amount of research before releasing anything. I'm pretty conflicted there.  Anyone who does the research and puts in the time deserves respect.

Scott actually doesn't disagree with the leg proportions anymore, he just thinks that the torso was depicted as a bit too long by Ibrahim et al. and that the sail shape may be incorrect. Oh, and he said he is working on updating his Spinosaurus skeletal.

[Blade-of-the-Moon]

I'd like to see what he comes up with.  Just about every dinosaur I've built here is based on Scott's work.

[Concavenator]

I was wondering this, but creating a new thread is unnecessary, so I'll  just post here (sorry if you entered thinking new material has been found  )

If we take into consideration Spinosaurus' really low slung proportions, wouldn't it have been a completely aquatic animal?It has always been believed that it was "semi-aquatic", until the 2014 discovery.However, the way Spinosaurus is portrayed now,it wouldn't have had any sense for a creature like that to venture into land.Why would it even go to land if it was a piscivore,and also there was the possibility of being attacked (and thereby killed, as such an animal would have been pretty vulnerable on land) by a Carcharodontosaurus or any other theropod?

The comparison with Ambulocetus is inevitable.Makes me wonder what would have happened if spinosaurids woudn't have become extinct,they would have probably became whale like creatures 

[Newt]

Two major reasons that I can think of:


1) laying eggs. It's always possible that Spinosaurus became viviparous, like plesiosaurs, ichthyosaurs, and mammals, but there is no evidence to indicate that it did. Amniote eggs do poorly in water.


2) getting from site to site. Estuarine environments, like those Spinosaurus fossils come from, are a complex mosaic of water of various depths, dry land, and intermittently inundated intertidal areas. Some fairly large fully aquatic animals use such areas today - dolphins, sirenians, various sharks - but nothing in Spinosaurus's size range. Such an animal would be at a great disadvantage in getting about in an estuary, frequently getting standed by outgoing tides (and then being vulnerable to predation by land-based predators such as Carcharodontosaurus) and unable to get to many prime feeding areas. If it moved further out to become fully pelagic, it would need to be able to swim well enough to catch prey and avoid predators "on the fin", and nothing about its morphology makes it seem like an effective swimmer.


So - I'm not saying Spinosaurus could not have been fully aquatic, but it had some serious hurdles to overcome.

[Tyto_Theropod]

Two major reasons that I can think of:


1) laying eggs. It's always possible that Spinosaurus became viviparous, like plesiosaurs, ichthyosaurs, and mammals, but there is no evidence to indicate that it did. Amniote eggs do poorly in water.


2) getting from site to site. Estuarine environments, like those Spinosaurus fossils come from, are a complex mosaic of water of various depths, dry land, and intermittently inundated intertidal areas. Some fairly large fully aquatic animals use such areas today - dolphins, sirenians, various sharks - but nothing in Spinosaurus's size range. Such an animal would be at a great disadvantage in getting about in an estuary, frequently getting standed by outgoing tides (and then being vulnerable to predation by land-based predators such as Carcharodontosaurus) and unable to get to many prime feeding areas. If it moved further out to become fully pelagic, it would need to be able to swim well enough to catch prey and avoid predators "on the fin", and nothing about its morphology makes it seem like an effective swimmer.


So - I'm not saying Spinosaurus could not have been fully aquatic, but it had some serious hurdles to overcome.

I know the comparison to crocodilians is cliche, but for some reason this makes me think of saltwater crocodiles: a large, formidable coastal species, mainly aquatic but equally capable on land.

[Lynx]

This is a strange concept but, what if spino was all three? Belly slider, quad, and bipedal. I know this is an old thread but I don't wanna make a new one.

Belly slider near shores, bipedal for short amounts of time, mainly for displaying or intimidation, and quad for faster land movement, but very rarely due to it mainly being an aquatic animal and quad movement likely being exhausting.

Since spino likely couldn't walk in the bipedal position presumed, it would be good for displays/making spino seem even larger than it is. The quad position would be clumsy and only for very short amounts of time to cross land faster, and belly sliding in muddy areas very close to the water, to get in and out faster.

[andrewsaurus rex]

I think the crocodilian lifestyle analogy for Spinosaurus is very realistic.  Not that it would mirror crocodiles in every way, but still similar.  Largely aquatic, wide ranging diet, comes on shore to sun itself and lay eggs, reasonably good swimmer etc.

I read lots of comments about all the things that Spinosaurus couldn't do, how it was fragile here and lumbering there and highly vulnerable in other ways.  Maybe so, but the fact is it did live, it thrived for a time and was quite successful as evidenced by it's huge size.  So it was a successful animal, regardless of precisely how it made a living, which we may never know because we may never fully understand all the nuances of its environment.

As far as predation by land theropods....how often do lions and hyenas attack and kill crocodiles?  I'm sure it happens but i'd bet it's pretty rare.   Even though Spino  may have been awkward on land it was still large, had big jaws and perhaps a tough hide?  Land predators may have had an abundance of easier game to hunt and would rarely bother to go after a Spinosaurus.  Besides, maybe it tasted awful.  So I don't think the threat of predation by terrestrial carnivores should be a factor in trying to figure out how Spinosaurus lived.

[Sim]

Planet Dinosaur showed there is a Spinosaurus vertebra that's broken which has been interpreted as being bitten by a Carcharodontosaurus.

[suspsy]

Jaguars regularly prey on caimans and lions and tigers have been documented killing crocodiles on land.

Also, carnivores generally don't care that much about the actual taste of meat so long as it's not too rotten. Survival is what's important.

[Pliosaurking]

Jaguars regularly prey on caimans and lions and tigers have been documented killing crocodiles on land.

Yes that's true but there either they are smaller or of a similar size, after a crocodilian reaches 14+ feet the tables turn. Spinosaurus was a fair bit larger than carcharodontosaurus, although these animals had different weapons and fighting styles than big cats and crocodilians, but ultimately it could go either way in my opinion.

[stargatedalek]

Jaguars regularly prey on caimans and lions and tigers have been documented killing crocodiles on land.

Also, carnivores generally don't care that much about the actual taste of meat so long as it's not too rotten. Survival is what's important.

Jaguars hunt caimans by planting their feet on the riverbed and lifting the caiman. Charcarodontosaurus was in no position to do anything equivalent to Spinosaurus.

[suspsy]

Jaguars regularly prey on caimans and lions and tigers have been documented killing crocodiles on land.

Also, carnivores generally don't care that much about the actual taste of meat so long as it's not too rotten. Survival is what's important.

Jaguars hunt caimans by planting their feet on the riverbed and lifting the caiman. Charcarodontosaurus was in no position to do anything equivalent to Spinosaurus.

Didn't say that it did, I was merely responding to the question as to whether land carnivores ever prey on crocodilians.

[Bread]

Slight confusion that may just apply to me.

Are we saying that Spinosaurus is the caiman/crocodile and Carcharodontosaurus is the tiger/jaguar? in these types of scenarios?

Maybe it is the way I am seeing it, because I don't find this a valid comparison. Extinct individuals built entirely different than extant individuals don't seem to be able to commit the same actions or hunting behaviors.

I just find it more acceptable to assume both therapods avoided each other at all costs. But of course I could be entirely wrong.

Edit: Of course they would interact if necessary but not casually hunting each other.

[andrewsaurus rex]

as I said in my earlier post, i'm sure there are examples of large predators hunting crocodiles, but it's not the norm.   Many herbivores eat meat once and a while when they need a boost of energy or nutrients, but it's not the norm either.  Pretty much anything that can happen, does happen in nature, but may time they are unusual occurrences.

I guess my point was that given that Spino did survive and thrive and was able to evolve to great size suggests that predation by terrestrial carnivores was not a big problem.  And given the fact that it was not ideally suited for an exclusively aquatic life, that implies it probably came on land for periods of time.  How did it avoid predation?   Maybe the sail was more than for display, maybe it was to intimidate predators and other rivals by making the animal look even larger.....much the same purpose that ceratopsian frills may have served..  Maybe the sail was covered in sharp barbs of some kind making Spino more awkward and dangerous to attack..  Maybe Spino was poisonous.   Or maybe it simply dashed into the water every time it got the whiff of a predator.

The subtleties of animal behaviour can sadly rarely be determined from skeletal remains, especially scant skeletal remains and thus much of animal's lifestyles and behaviour will always be a mystery, unfortunately.

At least until i finish my time machine.  I've got a long way to go though, it's proving to be a tricky problem to solve.

[Sim]

A @andrewsaurus, I doubt the sail of Spinosaurus was covered in sharp projections since, as I mentioned, there's a Spinosaurus vertebra which has been interpreted as being broken by the bite of a Carcharodontosaurus.  @Bread, this also suggests the two animals weren't avoiding each other at all costs.