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| Extinct Animal Questions | |
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| Topic Started: Nov 26 2013, 10:24 PM (193,440 Views) | |
| DinoBear | Nov 18 2014, 07:03 AM Post #811 |
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Wasn't aware of Tianyulong and Kulindadromeus fluff being completely different than that of theropods. |
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| CyborgIguana | Nov 18 2014, 07:51 AM Post #812 |
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I wasn't aware of this either, though it doesn't exactly surprise me. |
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| Incinerox | Nov 18 2014, 08:25 AM Post #813 |
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Āeksiot Zaldrīzoti
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Kulindadromeus: http://reptilis.net/wordpress/wp-content/uploads/2014/07/Filament_Interpretations.jpg http://2.bp.blogspot.com/-Eah44zYAiZM/U9a1NvDue4I/AAAAAAAAERg/I-yN-bbdBKo/s1600/Kulindadromeus+feathered+scales.jpg https://33.media.tumblr.com/f2dd61435b53e85646cecc5dd697fb82/tumblr_n9dkux2Ssl1tglztmo2_400.jpg Tianyulong: http://romangm.com/wp-content/uploads/2014/08/Tianyulong_Fossil_detail.jpg Tianyulong's wiry, bristly integument seems to match that of Psittacosaurus's tail, which was fundamentally more like iguana spines than theropod feathers under a microscope. Interesting in that those bristles were the only things to have been preserved, with no scales or feathers preserved in any kind of impression or outlined halo around the thing or anything like that. I suppose this would be one of the few examples where scaly or feathered integument based on phylogenetic bracketing is equally possible. But what I'm more interested in is Kulindadromeus's integument. The theropod feather condition seems to be like those seen on owl feet. Kulindadromeus, if those diagrams from papers interpreted the fossils right, suggest that it was literally doing something WEIRD, their filaments seem to be fraying in rows from the scales themselves rather than between the scales and in branches. Also, it's interesting to note that the scales they're sprouting from are like those small, rounded ones you see on theropod feet, but filaments themselves are behaving differently between the clades. Perhaps its these small rounded scales so prone to filamentous growth which were the norm across ornithodirans? Given the dormant genes for fluff in curotarsans, which show similar, albeit larger scales, it could be that this was THE archosaur integument. Bear in mind, I am more versed on theropod integument than I am on ornithischian integument. I suppose that's the general trend among paleontologists given the scarcity of ornithischian soft integument data, and how recently the data's been popping up. But anyway, I have a more pressing issue. Does anyone know where I'd be able to find pics (with scale bars) of the bones we know of for adult Megaraptor specimens, other than its thumb claws, ulna and scapula? I kinda need them for a personal project which actually might prove to be of genuine scientific importance. Edited by Incinerox, Nov 18 2014, 08:30 AM.
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| Even | Nov 18 2014, 09:19 AM Post #814 |
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Yeah, I think archosaurs as a whole are inherently prone of having some sort of integument... In this regard, theropod and ornithopod integument might be homologous after all... The original Megaraptor paper is sadly paywalled.. You might want to request for a copy from somewhere, like the Hell Creek forums... |
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| Incinerox | Nov 18 2014, 10:04 AM Post #815 |
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Āeksiot Zaldrīzoti
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I feel so ignored... ; ; |
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| CyborgIguana | Nov 18 2014, 01:18 PM Post #816 |
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NVM, I just realized how stupid this comment is. Edited by CyborgIguana, Nov 18 2014, 01:48 PM.
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| Luca9108 | Nov 18 2014, 02:22 PM Post #817 |
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Master of Dinosaurs
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Question: Is it possible that Postosuchus and coelophysis lived also in Europe? |
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| CyborgIguana | Nov 18 2014, 03:28 PM Post #818 |
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Not likely IMO, considering that their ecological niches were already filled there by related animals (such as Teratosaurus and Liliensternus, respectively).
Edited by CyborgIguana, Nov 18 2014, 03:29 PM.
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Nov 18 2014, 04:24 PM Post #819 |
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All I could find was a juvenile skull. ![]() I have no idea what the scale bar is representing but I'd think maybe 1cm because it's a juvenile.
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| Incinerox | Nov 18 2014, 05:10 PM Post #820 |
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Āeksiot Zaldrīzoti
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I am in possession of the juvenile's paper. Unfortunately it doesn't really help me with my planned composite reconstruction which currently requires Megaraptor's hands. |
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| stargatedalek | Nov 18 2014, 05:26 PM Post #821 |
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I'm not slow! That's just my moe!
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you failed to give me convincing evidence that there was no common ancestor you basically just said "they are different, I win" and then started dictating to people without giving any valid reasons to rule out a common ancestry |
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| Incinerox | Nov 19 2014, 04:37 AM Post #822 |
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Āeksiot Zaldrīzoti
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I felt I could safely claim victory there because the information I provided should've been self explanatory given what past posts have explained. But anyway, I have been asked to explain, so I shall... First things first, since we're referring to archosaurs as a whole regarding the integument battle, lets just quickly eliminate curotarsans from the fluffy equation. Every curotarsan with any sort of known integument shows them to be scuted to hell and back. Details hiddento save space It's pretty safe to say that the curotarsans as a whole were not endowed with any soft integument. And with that, its more likely that the common ancestor of the curotarsans was just as scaly. And yet even modern crocodilians has a dormant feather gene, and as a result, the type of keratin that forms feathers can be found in developing croc scales. That gene, and indeed that type of keratin, was most likely homologous throughout archosaurs. But given that the ancestor of curotarsans themselves was most likely scaly (abiding by the rules of phylogenetic bracketing), we have to assume that the ancestral feather did not originate this far back in the archosaur lineage. If we're looking for the ancestral dinofluff, we probably should narrow down our focus into the only clade of "reptiles" known to have had such integument - The Avemetatarsalia. So, you might wonder, pterosaurs and both dinosaur lineages had fuzzy integument of some kind, so SURELY their common ancestor had soft integument, right? Wrong. Pterosaur pycnofibers were short, flexible filaments and other than a central canal, there wasn't much to their internal structure. These fibers were arranged in dense mats like mammal fur on the face and the body, but not their wings, suggesting a thermoregulatory function for when small pterosaur ancestors started living more active, aerial lifestyles. But the kicker is that these pycnofibers were so different from either fur or dinosaur fluff that it actually warranted a new name to start with, and were UNIQUE to pterosaurs. Interestingly enough, the feet of pterosaurs have small tubercular scales like those on some dinosaurs (remember this bit, it'll be useful later). Before I focus on dinosaurs specifically, let me just sum up that because of the unique nature of pycnofibers, the differences between them and dinosaur feathers, and how they're not found outside pterosaurs at all, we have to conclude that dinosaur feathers and pterosaur fluff are not directly related. Therefore the ancestral Avemetatarsalia was likely just as scaly as the ancestral archosaur, following a baseline towards the dinosauromorphs. So. Dinosaurs. It gets a bit complex with dinosaurs because we're seeing two separate lineages, both sporting scaled and fluffy clades. We all know the story with the theropods as of the coelurosaurs. Soft integument consisted of a single shaft which frayed and brached until they formed complex downy feathers, which then evolved to zip together with barbules to create the complex structures known across the maniraptorans. We know the drill. But obviously it all has to get complicated. Ornithischian skin impressions are currently baffling scientists like theropod fluff did back in the 90s. Kulindadromeus's skin suggests that rather than fraying in barbs, filaments frayed from their tubercles arranged in odd rows. Then you've got the long quills of Psittacosaurus and Tianyulong which, under a microscope, are structured more similarly to an iguana's spines than to the quills of theropods. Then of course while the saurischians seem to have a nice, smooth transition between scaly and feathered integument, the ornithischians, through lack of data, still remains a bit of a cluster****. BUT. Once again we have something to tie them all back together. Two things in fact: 1) That specific keratin type. 2) Small, tubercular scales seen on pterosaur feet, theropod feet AND Kulindadromeus. Using phylogenetic bracketing to guide us on our path to enlightenment, we can safely justify that species anywhere between curotarsans and theropods had the gene coding for the keratins seen in both pterosaur and dinosaur fluff, and that everything in the Avemetatarsalia shared those small tubercular scales. And it's these scales, homologous among the Avemetatarsalia, which were the roots of all archosaur soft integument. If you want your common ancestor integument... LOOK NO FURTHER! I honestly do not know what further explanation is required. So in other words: "They are different. I win".
Edited by Incinerox, Nov 19 2014, 04:40 AM.
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| Iben | Nov 19 2014, 04:57 AM Post #823 |
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There'll be no foot-walking! Just air-flying!
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Is there a paper or an article on this actually ? It all sounds interesting, so I'd really want to read more about this. |
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| Incinerox | Nov 19 2014, 05:22 AM Post #824 |
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Āeksiot Zaldrīzoti
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Here ya go. Most of the info you'll need is the last few paragraphs just before the discussion on page 4. |
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| DinoBear | Nov 19 2014, 07:16 AM Post #825 |
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A relevant article. Not super new (2009), but it does deal with the subject. Also, does a skeletal or something similar exist for Goyocephale? Edited by DinoBear, Nov 19 2014, 07:17 AM.
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