Dimetrodon and Other Pelycosaurs May Have Lacked Sails

[Yutyrannus]

Very interesting stuff, unfortunately the paper is not open-access:
http://www.bioone.org/doi/abs/10.3158/2158-5520-5.1.104

An illustration by Traheripteryx on deviantart:

[Takama]

WTF is this legit?

[DinoLord]

From the abstract I get the impression that this finding only makes a specifically thermoregulatory sail unlikely.

[Balaur]

Well, from what we know about early non mammalian synapsids, I always thought of them as warm blooded animals, so having a sail for thermoregulatory purposes seems unnecessary. However, as display goes, yes, I find it likely.

[Yutyrannus]

WTF is this legit?

My thoughts exactly .

[SBell]

The spines of Edaphosaurus have small cross bars that connect the long vertebral processes. They would have required a connected covering, because only one type of bone remains outside of connective tissue permanently (teeth). And of those processes are connected, then then there would need to be flesh covering them. Can't speak to the kind.

It's unlikely that these enormous skeletal structures were not covered by muscle and tissue--like a bison, whose muscular shoulder hump is just very long vertebral processes.

Is it a sail, as oppose to a ridiculous fleshy ridge? Who knows. Part of the abstract even hints that the spines may have formed the basis for fat-storage, like a camel hump--which means it's important to ignore the Deviant Art reconstruction, because it clearly did not take that into account. They aren't just Sphenacodon with Longisquama frills on their backs.

[CityRaptor]

Giant spiky rats come to mind upon seeing that pic. Or Dimetrodons as they appear in Turok: Dinosaur Hunter.
http://turok.wikia.com/wiki/Dimetrodon

@Balaur: Actually large ears help an elephant to thermorgulate.

Given the abstract, it would probably mean that the sail is mainly for display.

[Saurian]

thanks for the info

[alexeratops]

[amargasaurus cazaui]

working on getting around the paywall..hang tough a minute.There , see if this works...There, full version free as a download of view only. Enjoy




https://app.box.com/s/rxzykp2qr5zuj7cd3b50d4vsg1j1zx9h

[HD-man]

Well, from what we know about early non mammalian synapsids, I always thought of them as warm blooded animals,

Source(s)? Last I checked ( http://www.academia.edu/4708990/Long_bone_histology_indicates_sympatric_species_of_Dimetrodon_Lower_Permian_Sphenacodontidae_ ), Dimetrodon was ectothermic.

[Yutyrannus]

working on getting around the paywall..hang tough a minute.There , see if this works...There, full version free as a download of view only. Enjoy




https://app.box.com/s/rxzykp2qr5zuj7cd3b50d4vsg1j1zx9h

Thank you !

[Plasticbeast95]

Now we should grab our popcorn and watch as everyone makes up some convoluted reason for a row of exposed vertebral spines.

[Dinoguy2]

Very interesting stuff, unfortunately the paper is not open-access:
http://www.bioone.org/doi/abs/10.3158/2158-5520-5.1.104

An illustration by Traheripteryx on deviantart:

Having read the paper, this image is still inaccurate. In complete specimens, the ends of the spines curl around in random directions, as the paper says, like Howard Hughes' fingernails This plus bone microstructure leads them to suggest that the sail didn't extend all the way to the spine tips but stopped with the straight part. IF this is correct, I'm assuming that means any restoration of Dimetrodon with straight spines is wrong. Those specimens must be restored based on Edaphosaurus. At least some species of Dimetrodon had bare curly-cue spines with straight, webbed bases.

[stargatedalek]

I wouldn't say that's inaccurate. Dimetrodon weren't born with damaged and bent spines, this happened either from injury or as they grew. And there's no necessity of a sail at all, the sail was always a presumption.

Edaphosaurus is something that I can't imagine possibly having a sail, it makes so much more sense without one.

[Tyrannosauron]

I wouldn't say that's inaccurate. Dimetrodon weren't born with damaged and bent spines, this happened either from injury or as they grew. And there's no necessity of a sail at all, the sail was always a presumption.

But Dinoguy has a point: all the paper argues is that the sail probably didn't extend to the tips of the spines. That doesn't imply that there wasn't any sail at all. If I say that my shirtsleeves don't extend all the way to my wrists, would it follow that I'm not wearing any shirt at all?

Edaphosaurus is something that I can't imagine possibly having a sail, it makes so much more sense without one.

Edaphosaurus is the sort of animal I have trouble imagining, period, but on what basis would say it makes more sense to imagine it without a sail? Like SBell said earlier in the thread: with the exception of teeth, all bones in all animals are covered by tissue. Edaphosaurus would be incredibly weird if its spines weren't covered by some sort of sail. With the sail the animal is merely weird. Why does "incredibly weird" make more sense than just "weird"?

[Dinoguy2]

I wouldn't say that's inaccurate. Dimetrodon weren't born with damaged and bent spines, this happened either from injury or as they grew. And there's no necessity of a sail at all, the sail was always a presumption.

Edaphosaurus is something that I can't imagine possibly having a sail, it makes so much more sense without one.

The damage to the spines and their bent nature are two different things. The spines that are the subject of the paper had a fracture, but their bent tops were natural. That's the reason the authors think the bent parts didn't have a sail.

As for Edaphosaurus, the authors of this paper say the bottom of Dimetrodon spines look more like edaphosaur spines, and therefore that part probably DID have a sail. Implying that Edaphosaurus had more sail than bare spines, or at least a bigger webbed portion of the spines.

[SBell]

I wouldn't say that's inaccurate. Dimetrodon weren't born with damaged and bent spines, this happened either from injury or as they grew. And there's no necessity of a sail at all, the sail was always a presumption.

Edaphosaurus is something that I can't imagine possibly having a sail, it makes so much more sense without one.

I'm not sure why this:



Makes more sense without some sort of sail. Those cross bars would only exist to support something, because otherwise they wouldn't have evolved--bones are metabolically expensive.

[Plasticbeast95]

I wouldn't say that's inaccurate. Dimetrodon weren't born with damaged and bent spines, this happened either from injury or as they grew. And there's no necessity of a sail at all, the sail was always a presumption.

Edaphosaurus is something that I can't imagine possibly having a sail, it makes so much more sense without one.

I'm not sure why this:



Makes more sense without some sort of sail. Those cross bars would only exist to support something, because otherwise they wouldn't have evolved--bones are metabolically expensive.

If Eddy did have a sail, it likely was very different to Dimetrodons sail.

[stargatedalek]

That's exactly what I mean, looking at those branch-lets I can't see how they would have supported a sail.