Spinosaurus new look!

[Balaur]

It doesn't seem like Spinosaurus would use its sail for attracting fish. It seems like an animal that actively hunts for fish rather than attract fish. Sensory pits on the snout would help it detect fish, then swim to them, and eat them.

Those are some cool pictures Gwangi. I like to think that Unenlagina employed a similar method.

[amanda]

Is it a done deal that it was a sail? I seem to remember some thought it could have been more of a hump than a sail?

[tyrantqueen]

They look like grisette mushrooms



Or maybe umbrellas.

[Lythronax]

What a mess,

We will have to wait until independent people do their own reconstructions (e.g. Scott Hartman). It is issues like these that make it obvious how scientists use headlines for self-promotion very often. The present work has it all:

1)   A popular dinosaur
2)   A popular paleontologist (Sereno), who has already made questionable claims to get headlines a few times before. We are still waiting for resolving the doubts about the Raptorex/Tarbosaurus baby based on dubious stratigraphical data. Sereno makes me remind about our Iberian Indiana Jones, Eudald Carbonell, who described Homo antecessor, though Sereno hasn't reached his level yet.
3)   National Geographic. To me, the scientific credibility of this magazine dangerously approaches that of Discovery Channel, because they favor image over real knowledge.
4)   Science. Here they say it much better than I will ever do. http://markwitton-com.blogspot.com.es/2014/09/the-spinosaurus-reboot-sailing-in.html
Where they make this devastating claim: "the suitability of their journal choice"

What's curious is that is seems to me that video reconstructions from National Geographic and the model of Geomodel have longer legs than the skeletal reconstructions. I personally like the model of Geomodel as a functional biped.

Transition forms can only survive as long as the ecological niche remains unnocupied, thus they tend to disappear with the passing of evolutionary time, being displaced by forms more adapted to the niche.

Mark Witton now says that it seems that the proportions are correct: http://markwitton-com.blogspot.com.es/2014/09/the-spinosaurus-hindlimb-controversy.html

[Lythronax]

According to the researchers, the proportions are those of the skeleton. If they are so convinced about this, it would be interesting to hear them say: "we will have to find an answer to the questions facing us, namely, how such a transitional form like this can exist, one that is not able to walk efficiently on the ground (quadruped theropod), in an environment full of terrestrial superpredators, and one that is a worse swimmer than coetaneous aquatic superpredators." (Besides, a mega-crocodile would certainly walk on the ground more efficiently than a quadruped Spinosaurus). Instead, the researchers say that this finding helps explain a lot of things about the biology of this group of dinosaurs, and that is enables us to know how these animals walked around the muddy environments of their habitat, they even talk about an evolutionary trend in the family Spinosauridae.

So, dear people, there exists an ichnite trail that may shed light on spinosaurid locomotion when going into and out of the water. Some of the most important ichnite sites from the Lower Cretaceous are found in the province of La Rioja, in Spain (Southern Europe), in an estuarine environment similar to that where Spinosaurus lived. One of these sites is "El Villar Poyales", where trails from various small theropods can be found, there is even a track of a theropod going into the water (which gives us an indication on the placement of the shore). There is also a trail of a large theropod going out of the water. Its footprints are webbed and plantigrade. The ichnospecies is called Theroplantigrada encisensis. The footprint has large interdigital membranes between the four fingers, similar to those of a duck. Here you have the holotype.



The trail begins inside the water, with footprints that are set apart more than it is usual for a theropod, and that gradually get closer to one another as the track moves away from the water. The whole track is bipedal and has no marks from either the belly or the tail whatsoever. Thus this theropod didn't glide on the mud, but walked clumsily with outwardly pointed feet in order to go into and out of the water. Here you have the trail. In green you can see the trail of a theropod that was obviously going into the water (there are even marks of the moment the pond becomes too deep for the dinosaur to touch the bottom).



I first knew about this track ten years ago and back then it was not known which theropod group it belonged to. It is clear that this theropod could not walk on the ground as good as typical theropods, so it may be a species tightly associated to aquatic enviroments. Some years have gone by and at the moment the single group of large theropods that are linked to aquatic environments are Spinosaurids. Thus, to me, it is most probable that this track belongs to a Baryonyx or to a similar species. I know that Baryonychinae are not entirely equal to Spinosaurinae and so their mode of locomotion could be somewhat different. However, I have read in more than one place people claiming that because Baryonychinae have a long trunk, they would certainly tend to move by gliding on the mud and that with the passing of evolutionary time, this mode of locomotion would become more efficient by a reduction in leg length until Spinosaurus. Therefore, if the trail of "El Villar de Poyales" belongs to a Baryonyx, this argument becomes invalid.

And if this trail hasn't been mentioned before, it is surely the fault of the people studying these sites, which is another example on how Spain works.

[Lythronax]

I agree with people like Scott Hartman. Overall, the content of the article is ok. I'm waiting for new reconstructions. To me, the sailess tail makes more sense than a normal sail running along the spine, because the tail has more freedom to move and can fulfill its function of maintaining the balance. Besides, copulation would certainly be easier, because the tail would be easier to move. Before this finding I thought that the reconstruction of the large sail was not entirely adequate, and that it should certainly be divided into two smaller parts, as in Ichthyovenator. This would allow for the separation of the movements between tail and trunk, as it happens nowadays with Basiliscus plumifrons. But this idea must now wait until new reconstructions come out, we will whether researchers decide to shift the position of the vertebrae again.

In opinion, webbed feet and the shape of the neck fit very well into a hunting mode similar to one depicted below: The Spinosaurus would be waiting semi-submerged, with the back outside the water to capture heat from the sun. In this respect, I think the shape of the neck fits better into this lifestile than into the lifestyle of a theropod that captures fish while swimming. Webbed feet would allow Spinosaurus to jump suddenly to capture larger prey.


http://dontmesswithdinosaurs.com/?p=402

The hunting method shown in the illustration is also compatible with a reduction in leg length, but still being a functional biped.

If I may, I attach a picture that I modified to think about a color outline to paint a dinosaur model I plan to buy soon. I took some inspiration on Ardeidae birds. Spinosaurus would have a white belly to camouflage itself from prey fish from below, and grey-brown flanks because it probably fished in turbid waters. It also had a black back that allowed it to warm up under the sun. Such an animal may thus be mesothermic and spend long hours among waters colder than their corporal temperature without incurring high energy costs. According to this interpretation of my own, if Spinosaurus used the sail as a thermoregulatory organ, it may be possible that it was able to change the hue (from dark to light) to avoid hyperthermia, just as wall geckoes do (Tarentola sp.)



With regard to sexual selection, it seems that Spinosaurus retains the primitive condition in theropods, that of using cranial elements as a secondary sexual character to attract individuals from the opposite sex. Now, evolutionary biology has proved that a structure that first evolved with a given function it can acquire additional functions later on that have nothing to with the original one. Thus, because the sail is an elevated surface that can be seen from a distance and that is able to show the size of the individual, it is not entirely crazy to imagine that in the reproductive season the sail would show spectacular colors that would indicate the body condition of the individual, as a sexually selected honest character. However, I made this drawing one year ago, and since then I have been thinking about it and now I don't like it. Now I think that there is another pattern of spots that would be better at indicating the size of the animal and so would be a better honest character.

Another sailed dinosaur named Ouranosaurus (from the same area of Spinosaurus) may have had a sail due to similar evolutionary pressures than Spinosaurus. It could be that this euornithopod fed on subaquatic vegetation for long hours and thus the sail evolved to avoid excessive cooling. This would be nice to study with dental isotopes, as it has been done in Spinosaurus.

[Balaur]

Is it a done deal that it was a sail? I seem to remember some thought it could have been more of a hump than a sail?

I'm still not totally sold on the idea that it is a sail. The spines are thicker than those that made the sail of Dimetrodon, more like the humps seen in bison.

Maybe it had multiple functions.

[DC]

Is it a done deal that it was a sail? I seem to remember some thought it could have been more of a hump than a sail?

I'm still not totally sold on the idea that it is a sail. The spines are thicker than those that made the sail of Dimetrodon, more like the humps seen in bison.

Maybe it had multiple functions.

National Geographic exhibit describes the new material showing muscle attachments that would indicate the long back bones were tightly covered with a layer of skin.

[Lythronax]

Is it a done deal that it was a sail? I seem to remember some thought it could have been more of a hump than a sail?

I'm still not totally sold on the idea that it is a sail. The spines are thicker than those that made the sail of Dimetrodon, more like the humps seen in bison.

Maybe it had multiple functions.

National Geographic exhibit describes the new material showing muscle attachments that would indicate the long back bones were tightly covered with a layer of skin.

A part from what DC says, if Spinosaurus had a hump it would shift the center of gravity so much forward that the animal would need to become strictly quadruped and that the arms would receive too much weight to support the animal (we must remember that Spinosaurus lacks adaptations int he arms for quadruped locomotion). This would not affect Ouranosaurus in its day-to-day movements, because it usually walked on 4 legs, but ornithopodans ran away in a bipedal position (which would be impossible with the hump).

A dinosaur where the hump makes more sense is Concavenator, because the hump would be just above its center of gravity. This way, neither the mode of locomotion nor the ability to turn while running are affected. Concavenator's hump was certainly useful in a time of the year when prey were not abundant. Or it could be that Covenator need not feed that much during the reproductive season.

[amargasaurus cazaui]

Add another dinosaur that had a sail from the same geographical arena Amargasaurus...a sauropod , iguanodont and a thera-something or other all using the same or similar structures. This is something that has had me puzzled for years......what was the one thing they all shared? The same or similar location....which also happens to be where the only sauropods seemed to thrive well into the Cretaceous.

[Sim]

Add another dinosaur that had a sail from the same geographical arena Amargasaurus...a sauropod , iguanodont and a thera-something or other all using the same or similar structures. This is something that has had me puzzled for years......what was the one thing they all shared? The same or similar location....which also happens to be where the only sauropods seemed to thrive well into the Cretaceous.

As far as I'm aware, it's not known if there was anything between Amargasaurus' spines.

[stargatedalek]

-a shrink wrapped sail is unlikely, the supporting structures are nothing alike to those of pelycosaurs
-a thick hump was equally unlikely, bison and rhinoceros humps are supported all the way to the top of the neural 'spines', whereas those of spinosaurus get narrower as they rise
-a chameleon is the only analogue that really works, the 'spines' are very similar in how they narrow as they rise, spinosaurus most likely had a structure similar in thickness to a chameleon

-the most likely option it would have been a thick ridge, starting with the thickness of the back and rising in a way that it would narrow as it rises, a cross-section of the ridge would resemble a triangle

[Scipionyx]

I finally understand: Spinosaurus was a sailboat that was also the loch ness monster!

[amargasaurus cazaui]

Add another dinosaur that had a sail from the same geographical arena Amargasaurus...a sauropod , iguanodont and a thera-something or other all using the same or similar structures. This is something that has had me puzzled for years......what was the one thing they all shared? The same or similar location....which also happens to be where the only sauropods seemed to thrive well into the Cretaceous.

As far as I'm aware, it's not known if there was anything between Amargasaurus' spines.

I quite agree with your comment there , however it would seem possible or perhaps likely once you consider the other animals. Aside from that, you could argue there is no definite proof anything covered Spinosaurus spines although conventional logic seems to suggest so. It is a huge puzzle but I think a piece is still missing somewhere.
  Myself I think the sail was for used to perserve body temperature , and the animal was not a true warm blood.

[Sim]

Add another dinosaur that had a sail from the same geographical arena Amargasaurus...a sauropod , iguanodont and a thera-something or other all using the same or similar structures. This is something that has had me puzzled for years......what was the one thing they all shared? The same or similar location....which also happens to be where the only sauropods seemed to thrive well into the Cretaceous.

As far as I'm aware, it's not known if there was anything between Amargasaurus' spines.

I quite agree with your comment there , however it would seem possible or perhaps likely once you consider the other animals. Aside from that, you could argue there is no definite proof anything covered Spinosaurus spines although conventional logic seems to suggest so. It is a huge puzzle but I think a piece is still missing somewhere.
  Myself I think the sail was for used to perserve body temperature , and the animal was not a true warm blood.

The spines on Amargasaurus' neck are circular in cross section, while Spinosaurus' and Ouranosaurus' spines have flattened cross sections.  This might mean there's a physical difference that isn't limited to the bones.  It makes me think Amargasaurus neck spines had a more direct role in defense than Ouranosaurus and Spinosaurus spines.  Wait, you're an Amargasaurus aren't you?  You can end our speculation on what an Amargasaurus looks like! 

[stargatedalek]

there is no evidence that spinosaurus wasn't a "true warm blood"
no direct evidence that it was either, but the point still stands

[Dinoguy2]

People are questioning how a fully aquatic spino could compete with "super crocs" but which super crocs lived inhe same time and place? Sarcosuchus is several million years older and lived alongside Suchomimus, not Spinosaurus. Many species of smaller crocs lived alongside Spino and yet somehow they managed not to all kill each other off.

Arguments like this seem to rely on the fallacy of the Mesozoic as a life or death struggle of constantly warring monsters when in reality animals can have subtle niche partitioning not necessarily obvious from anatomy alone, and that predators tend to avoid conflict wih each other whenever possible.

The large size of adult spino alone may have been enoughto deter attack from carchs, much like sauropods. I'm not saying the ungainly Spinosaurus never got killed by more agile carnosaurs, just that it may have been rare enough to not have had a major impact or as everyone optionally pressure.

He fact is the bloggers were wrong and have admitted such public ally, the published proportions are right, and we just need a hypothesis to explain how spino actually lived. I personally don't agree it was a quadruped, I think it could have walked pangolin or Godzilla style just fine on two legs. But it would have been relatively awkward on land and certainly was not capable of running.

[HD-man]

People are questioning how a fully aquatic spino could compete with "super crocs" but which super crocs lived inhe same time and place?

Semi-aquatic: http://www.sciencemag.org/content/early/2014/09/10/science.1258750

[stargatedalek]

there were a few large crocodilians living alongside spinosaurus, however they were extremely specialized, and likely wouldn't have even competed for prey let alone fought

[Balaur]

there were a few large crocodilians living alongside spinosaurus, however they were extremely specialized, and likely wouldn't have even competed for prey let alone fought

Seems like most of the animals that lived with Spinosaurus were extremely specialized. It's a very interesting ecosystem. I don't think there is something quite like it today. Also, what about Aegisuchus, the giant shieldcroc? What niche did it fill?

I'm thinking that Spinosaurus may have occasionally fed on the smaller crocs, like Elosuchus, and subadult Lagonosuchus. I doubt that they competed for food though.