Dimetrodon's sail

[Stegotyranno420]

not to mention it somewhat breaks rules 4 and 6

back on the main topic, A @andrewsaurus , i know this idea may seem outlandish and unsupported by evidence, but you know how chameleons change their colors to communicate or show signals, maybe dimetrodon might have used its sail as some sort of biological billboard. I'm not a fan of this theory, but it's still interesting and I thought you might want to know. (and I don't mean complex language, but rather simple things like if they are sick or if they are ready to mate, based on the shade of the sail)

[andrewsaurus rex]

I don't think it's that far fetched an idea....I mentioned it in one of my posts above.  Sail colour (or pattern) could vary for anger, fear, excitement, come hither etc.

[Stegotyranno420]

True, I was more caught up in the other sub topic than the actual topic so I didn't realize . Sorry

[andrewsaurus rex]

no worries, I wasn't accusing you of stealing my idea or anything....just pointing out that great minds think alike...lol.

I got the notion from a post that was prior to mine or that I saw somewhere else and just expanded on it a bit.  I think it's a very reasonable concept.  The sail on the collecta Edaphosaurus figure has a pinkish cast to it which I interpret as sending a message to fellow Edaphosauruses,  maybe 'danger' or something.

[Faelrin]

Come to think of it, I'm pretty sure Edaphosaurus (a different synapsid) and Platyhystrix (a temnospondyl), lived with at least one species of Dimetrodon if not more. Some kind of interesting selection pressures were going on in the late Carboniferous to early Permian to lead to several different genera that all share a similar feature what with having a sail. Some even from the same locality I believe (such as the Texas Red Beds)? Some weird case of convergent evolution or something more going on? Kind of something I forgot to mention earlier, but it's been on my mind on and off a bit now.


Edit: @Stegotyranno420 I think it is an interesting idea. Would certainly look interesting in an illustration or something at least. I too wonder how plausible that could be though, now that you've brought that up.

[Newt]

There were multiple contemporary sail-backed synapsids  - not only the famous Dimetrodon and Edaphosaurus, but Ianthasaurus, Ctenospondylus, Lupeosaurus, Gordodon, and everybody's favorite, Secodontosaurus. Platyhystrix also had a lower-sailed cousin, Astreptorhachis, that lived beside "Edaphosaurus" raymondi in the Late Pennsylvanian of Ohio.

[andrewsaurus rex]

which to me, suggests there was some purpose to the sail, aside from being for display, that caused so many animals to sprout them around the same time...the only other instance of that i'm aware of was when Ouranosaurus and Suchomimus co-existed.

[Faelrin]

@Newt Thanks for pointing all those out. I knew about them but forgot at the time of making my post (been doing a lot of that recently unfortunately). A shame as some of those are on my figure wishlist too (such as Gordodon and Secodontosaurus). So I appreciate the reminder. I however was not aware of Astreptorhachis, so I'll need to do some research on that one.

[Bowhead Whale]

Well, even after having read all that discussion, I still think this sail is for thermoregulation. Consider it: stegosaurids had back plates, ceratopsians had frills and many ancient animals had sails. Dinosaurs like Spinosaurus and Ouranosaurus also had sails and Acrocanthosaurus may have had one as well, even if it was smaller. Plus, Ouranosaurus and Spinosaurus were found in about the same areas, which probably means they developped sails for the same reason, in a convergence. And I think frills, sails, vertical plates all had thermoregulation for first function. The animals who had no frills/plates/sails/ may have been the way they were simply because they thermoregulated in another way, maybe simply by a faster metabolism. What do you think?

[Newt]

Stegosaurid plates and ceratopsian frills would have been fairly ineffective as thermoregulatory devices, as they were only modestly vascularized (you can tell because blood vessels leave grooves on bone covered by thin soft tissue); if you want a good radiator or heat collector, you need to be able to pump a lot of blood through it, as blood circulation is what moves heat through the body (that's why you get flushed when you're hot - your body is pumping blood into your dermal capillaries to give it a chance to shed heat into the atmosphere).

You could argue that the vertebral sails of various taxa might have been more heavily vascularized, but that the blood vessels were concentrated in the membrane between the bones, therefore not marking the bones - but I think that would be special pleading without other evidence to back up this line of reasoning.

Another important point is how variable sail shapes are. If they were for thermoregulation, taxa with the same bauplan ought to converge on similar sail shapes due to the mechanics of thermoregulation. Instead, even species within the same genus have wildly varying sail shapes and proportions (for example, larger species of Edaphosaurus had proportionally lower sails, while larger species of Dimetrodon had proportionally higher ones). Stegosaur plates and ceratopsian frills are even more marked in their variation. Similar variation can be seen in hadrosaur crests, elephant tusks, artiodactyl horns and antlers, and the display plumage of birds - all structures used primarily in intraspecific display and agonism.

One last thing to keep in mind is that not all sails were the same - Acrocanthosaurus' so-called sail, for instance, has all the hallmarks of a mechanical support for muscles and tendons, like the withers of a horse or bison. So there is no one-size-fits-all answer for "what are sails for".

[stargatedalek]

We know why Spinosaurus and Ouranosaurus have sails, they are muscle attachments. And unless something is seriously about to shake up how we picture it I don't think Ouranosaurus has a giant tail for underwater propulsion it used those muscles for, meaning it was pure chance they lived together.

[andrewsaurus rex]

why did Ouranosaurus, or Spinosaurus for that matter, have such enormous spines for muscle attachment along the torso?  What were the muscles attached to the spines doing?  Seems a very odd location to have huge muscles attached  Big spines over the shoulders makes sense if the animal has a heavy head.  Big spines over the hips would make sense to move a big powerful tail.

But big spines in the middle of the back don't make any sense.....what is the need for huge muscle attachments there? 

[stargatedalek]

why did Ouranosaurus, or Spinosaurus for that matter, have such enormous spines for muscle attachment along the torso?  What were the muscles attached to the spines doing?  Seems a very odd location to have huge muscles attached  Big spines over the shoulders makes sense if the animal has a heavy head.  Big spines over the hips would make sense to move a big powerful tail.

But big spines in the middle of the back don't make any sense.....what is the need for huge muscle attachments there?

Well, Spinosaurus has both an undulating tail and a very long neck with a large head, with the enlarged columns pointing towards each direction. Ouranosaurus spines however are only forward facing, not in the middle of the back but possibly even well within the musculature of the neck.

[Brocc21]

why did Ouranosaurus, or Spinosaurus for that matter, have such enormous spines for muscle attachment along the torso?  What were the muscles attached to the spines doing?  Seems a very odd location to have huge muscles attached  Big spines over the shoulders makes sense if the animal has a heavy head.  Big spines over the hips would make sense to move a big powerful tail.

But big spines in the middle of the back don't make any sense.....what is the need for huge muscle attachments there?

Well, Spinosaurus has both an undulating tail and a very long neck with a large head, with the enlarged columns pointing towards each direction. Ouranosaurus spines however are only forward facing, not in the middle of the back but possibly even well within the musculature of the neck.

I think It's also worth mentioning that if your an animal who spends a lot of time submerged. If may be benificial that you have a gigantic hard to miss piece of you that stays out of the water, just to let everyone know who you are and what your territory is.

[andrewsaurus rex]

it may also have benefits of keeping you warm when you're submerged.  However a sail is not useful if you are an ambush predator nor is it really useful for swimming under water, as it would act like a big, upside down keel creating resistance during lateral movement.

Stargatedalek: I looked at the Ouranosaurus skeleton and it seems to have long spines running the entire length of the back; maybe i'm just not understanding what you mean by 'forward facing'.

[Reuben03]

bruh i dont care about all these smurfs and terfs i just wanna learn about my favorite animal

[stargatedalek]

bruh i dont care about all these smurfs and terfs i just wanna learn about my favorite animal

What are you talking about? You mean the talk of Spinosaurus and such?

If so, I concur. There is nothing similar about the structures of them and Dimetrodon aside from just being a dorsal structure in general.

[Bowhead Whale]

it may also have benefits of keeping you warm when you're submerged.  However a sail is not useful if you are an ambush predator nor is it really useful for swimming under water, as it would act like a big, upside down keel creating resistance during lateral movement.

Stargatedalek: I looked at the Ouranosaurus skeleton and it seems to have long spines running the entire length of the back; maybe i'm just not understanding what you mean by 'forward facing'.

The sail is not a problem of ambush when you eat fish: fish do nont necessarily look at what is above water, unless they feed on insects. Spinosaurus skull has many holes on it like sharks and crocodiles. These holes were pressure sensors, like those of those modern animals. That means Spinosaurus ate fish, not land animals. No?

As for talking about Spinosaurus, well, I don't think we can understand the frill of Dimetrodon if we don't compare it with sails of other animals. When we want to understand a feature, we look at other animals with a similar feature. No?

[stargatedalek]

it may also have benefits of keeping you warm when you're submerged.  However a sail is not useful if you are an ambush predator nor is it really useful for swimming under water, as it would act like a big, upside down keel creating resistance during lateral movement.

Stargatedalek: I looked at the Ouranosaurus skeleton and it seems to have long spines running the entire length of the back; maybe i'm just not understanding what you mean by 'forward facing'.

The sail is not a problem of ambush when you eat fish: fish do nont necessarily look at what is above water, unless they feed on insects. Spinosaurus skull has many holes on it like sharks and crocodiles. These holes were pressure sensors, like those of those modern animals. That means Spinosaurus ate fish, not land animals. No?

As for talking about Spinosaurus, well, I don't think we can understand the frill of Dimetrodon if we don't compare it with sails of other animals. When we want to understand a feature, we look at other animals with a similar feature. No?

These are not similar features. Spinosaurus had very large broad extensions of its vertebrae. These are broad as they are in bison and rhinoceros because they are attachments for musculature. Dimetrodon and kin have tiny thin shafts extending from the vertebrae, not large segments extending vertically. They are like the sail supporting structures of basilisks and similar lizards.

[Reuben03]

bruh i dont care about all these smurfs and terfs i just wanna learn about my favorite animal

What are you talking about? You mean the talk of Spinosaurus and such?

If so, I concur. There is nothing similar about the structures of them and Dimetrodon aside from just being a dorsal structure in general.

no i mean dimetrodon haha its my faaavourite
didnt see we were back on track i was still on page one and didnt know there was a page two of this discussion where everyone was back on subject