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Extinct Animal Questions
Topic Started: Nov 26 2013, 10:24 PM (193,293 Views)
CyborgIguana
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So I take it that no one knows the answer to my question? No big deal, it only relates vaguely to palaeontology in any case.
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Acinonyx Jubatus
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I AM THE UNSHRINKWRAPPER!

CyborgIguana
May 4 2016, 03:28 PM
So I take it that no one knows the answer to my question? No big deal, it only relates vaguely to palaeontology in any case.
I'm sorry, I'm not very familiar with radiometric dating. :( I'd be interested to know the answer, though.

In addition to my earlier question, what is the likelihood of Dimetrodon having fur or proto-fur in any amount on its body?
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heliosphoros
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Hard to say. The only well established non-therapsid synapsid integument we know is from varanopsids, which are as closely related to Dimetrodon as they are to us.
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CyborgIguana
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Well, it was a Facebook comment so I probably shouldn't take it too seriously.

Anyway, IIRC we have skin impressions from Dimetrodon that show a leathery, rhino-like hide but it's a known fact that skin of that type can easily support hair so I'd say there's a decent possibility of it.

EDIT: Ninja'd.
Edited by CyborgIguana, May 4 2016, 04:32 PM.
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Acinonyx Jubatus
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Acinonyx Jubatus
May 4 2016, 03:08 PM
So I understand Dimetrodon's spines were figure-8 shaped in cross-section, with a groove running down each side. I believe it was said that this structure strengthened the spine and prevented bending. What I want to know is, in which planes were bending restricted? Would it have been rather flexible from side-to-side and stiff front-and-back, or stiff all 'round? And would the groove have housed some sort of soft tissue or vascularization?

Actually, does anyone have a complete, detailed diagram of an entire Dimetrodon vertebra, including the spine?
And also:

-I can't see an Infraorbital Foramen on Dimetrodon's (or any non-mammalian synapsid) skull. Does this mean they lacked the nerves required for mobile, mammalian lips?
-What would the flight pattern of a Meganeuropsis have been like? I presume the energy required to lift 2 or 3 pounds of insect off the ground would be significantly different than that of a modern dragonfly. Would it have flapped slower or faster? Would it have had to glide more often, resting its wing muscles? Have any studies been done on this?
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Yi Qi
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heliosphoros
May 4 2016, 04:29 PM
Hard to say. The only well established non-therapsid synapsid integument we know is from varanopsids, which are as closely related to Dimetrodon as they are to us.
Wrong

http://www.tandfonline.com/doi/abs/10.1080/10420940.2012.702549#.VyqHL4QrKUl
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2736118/pdf/joa0214-0441.pdf
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2288685/

Apparently what we have is.

-Most of the body covered by leathery, mammal like bare skin
-Belly and at least sections of the tail being covered in dermal keratinous structures similar to those you'd find today in the tail of a mouse or an opossum.
-Some pelycosaurs (Mainly Edaphosaurs) had weird keratinous osteoderms on their sails
-The extent of the pelycosaur sail is actually highly debateable and apparently very varied (It seems complete in Edaphosaurus but incomplete in atleast one species of dimetrodon).

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heliosphoros
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Two of thoese references reffer specifically to varonopsids, not Dimetrodon, as I said.
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Incinerox
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heliosphoros
May 4 2016, 04:29 PM
The only well established non-therapsid synapsid integument we know is from varanopsids, which are as closely related to Dimetrodon as they are to us.
Not sure if serious or blatant hyperbole.
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heliosphoros
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I am serious. Varanopsids are outside the clade that includes sphenocodontids + therapsids.
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Yi Qi
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heliosphoros
May 5 2016, 02:50 PM
I am serious. Varanopsids are outside the clade that includes sphenocodontids + therapsids.
Varanopidae are part of the greater Eupelycosauria, being sister clades to Both Edaphosauridae and Sphenacodontia. They may be outside of the later, but they are close enough in that we can probably infer their integument in the earliest of Sphenacodontians by parsimony.
Edited by Yi Qi, May 5 2016, 07:34 PM.
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Paleop
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Paleopterix

my turkeys and chickens grow their wing feathers before any of their chick-fuzz gets replaced by body feathers would dromaeosaurs (particularly deinonychus) also grow their feathers out in the same way?
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heliosphoros
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Yi Qi
May 5 2016, 07:33 PM
heliosphoros
May 5 2016, 02:50 PM
I am serious. Varanopsids are outside the clade that includes sphenocodontids + therapsids.
Varanopidae are part of the greater Eupelycosauria, being sister clades to Both Edaphosauridae and Sphenacodontia. They may be outside of the later, but they are close enough in that we can probably infer their integument in the earliest of Sphenacodontians by parsimony.

Yet sphenacodontians not only are closer to therapsids, but also display traits absent in varonopsids (upright gaits, heterodont dentition, et cetera), so it's entirely possible that several factors in regards to their integument don't match up.

For all we know, sphenocaodontians might have already developed fur
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Yi Qi
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heliosphoros
May 5 2016, 10:39 PM
Yi Qi
May 5 2016, 07:33 PM
heliosphoros
May 5 2016, 02:50 PM
I am serious. Varanopsids are outside the clade that includes sphenocodontids + therapsids.
Varanopidae are part of the greater Eupelycosauria, being sister clades to Both Edaphosauridae and Sphenacodontia. They may be outside of the later, but they are close enough in that we can probably infer their integument in the earliest of Sphenacodontians by parsimony.

Yet sphenacodontians not only are closer to therapsids, but also display traits absent in varonopsids (upright gaits, heterodont dentition, et cetera), so it's entirely possible that several factors in regards to their integument don't match up.

For all we know, sphenocaodontians might have already developed fur
If by Sphenacodontians you mean Therapsids then yes, we know that atleast SOME therapsid groups most definately had fur by studies of late and middle permian coprolites IIRC

We also know some therapsids like Dinocephalians were mostly covered on bare, hippo like skin, like Estemmenosuchus, pushing the development of fur to somewhere on the post dinocephalian horizon.

However if you mean Sphenacodontid then, its unlikely, the pressure for the development of fur was likely the sudden mid to early late permian cooling of the earth (Megawhaiitsia,Inostrancevia and Scutosaurus's habitat looked VERY differently than what the media depicts, it was by all means a very cold, temperate and high altitude habitat.), long after Dimetrodon and its ilk have gone extinct.

Vibrissae (Whiskers) however, which by all accounts likely preceded fur by at the very least a few tens of millions of years, could very likely be present in both Sphenacodontids and most therapsid groups though.
Edited by Yi Qi, May 5 2016, 11:41 PM.
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Incinerox
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Āeksiot Zaldrīzoti

heliosphoros
May 5 2016, 10:39 PM
Yi Qi
May 5 2016, 07:33 PM
heliosphoros
May 5 2016, 02:50 PM
I am serious. Varanopsids are outside the clade that includes sphenocodontids + therapsids.
Varanopidae are part of the greater Eupelycosauria, being sister clades to Both Edaphosauridae and Sphenacodontia. They may be outside of the later, but they are close enough in that we can probably infer their integument in the earliest of Sphenacodontians by parsimony.

Yet sphenacodontians not only are closer to therapsids, but also display traits absent in varonopsids (upright gaits, heterodont dentition, et cetera), so it's entirely possible that several factors in regards to their integument don't match up.

For all we know, sphenocaodontians might have already developed fur
By your logic, Megalosauroids were more closely related to chickens than they were to basal ceratosaurs.

But clearly, two branches are much further apart than the roots of a tree and its crown.
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stargatedalek
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I'm not slow! That's just my moe!

Paleop
May 5 2016, 09:53 PM
my turkeys and chickens grow their wing feathers before any of their chick-fuzz gets replaced by body feathers would dromaeosaurs (particularly deinonychus) also grow their feathers out in the same way?


It's possible that that might even be a growth pattern inherited from feathered dinosaurs developing wings while still being mainly covered in down, as all birds develop that way. Don't quote me on that though as I don't recall where I heard it from.
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