Talk:Dromaeosauridae

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I have copied the following from Talk:Dinosaur with the thought that this side issue might be more directly relevant here. I'm not competent to discuss this myself. --Wetman 18:01, 20 Nov 2004 (UTC)

There are two very famous (or if you will, infamous) theories about non-flying dinosaurs being the descendants of flying forms. The "weak" version is from Gregory S. Paul who holds that dromaeosaurs (and probably other Maniraptora) are a sistergroup of Aves (or Avialae), rather than Aves being within dromaeosaurs (the mainstream theory). He already predicted this in 1988. Since then most new evidence confirmed his hypothesis, especially that from China: theropods did have feathers (and indeed the earlier they had feathers, the more likely his conjecture); some basal dromaeosaurs were small and could at least glide (Microraptor, Cryptovolans pauli (got it? ;o)). Nevertheless, cladistic analysis still shows that this alternative possibility is somewhat more unlikely, though not implausible. Perhaps the most elegant explanation of the facts would be that Maniraptora had a flying ancestor that wasn't a bird. This thought is taken to the extreme by the "strong" version by George Olshevsky that claims that all dinosaurs are decendants of small flying, or at least gliding, or certainly treeliving small forms in the Triassic. This version is called BCF (Birds Came First): the main engine of dinosaur evolution is supposed to be a hidden lineage of small arboreal forms. These wouldn't be birds of course, they would just be feathered, warmblooded, flying eh..."birds". The problem with this theory is that early dinosaurs don't show clear flight adaptations (but then do dromaeosaurs show these? Yes.) so real flight is unlikely before the node of Tetanurae. Arboreality though is not and more and more theories go in this direction in combination with a "trees-down" explanation of flight - although Olshevsky is rarely credited for it. Well, whoever said life is fair? If you would like to know more about these things, I heartily recommend Paul's Dinosaurs of the Air, being well worth its (not inconsiderable amount of) money. MWAK--84.27.81.59 09:56, 20 Nov 2004

Contents 1 What this page needs 2 Clarification Issues 3 "Almost Certain" 4 Microraptoria 5 Class

[edit] What this page needs

• A taxobox
• Some greater clarity about exactly which dinosaurs belong in this group

The Singing Badger 18:23, 25 Nov 2004 (UTC)

Agreed, but the whole clade is kind of topsy-turvy. Here is an interesting (and current) analysis: [1] 68.81.231.127 05:18, 26 Nov 2004 (UTC)

Removed the sinornithosaurs--will add them to their own family, Microraptoria, per most current research. Dinoguy2 05:40, 10 December 2005 (UTC)

[edit] Clarification Issues

From the article:

This also leads to the question whether all dromaeosaurids bore feathers, which at this point is uncertain.

Given that much more primitive dinosaurs like Dilong and Sinosauropteryx had feathers, the fact that basal maniraptoran Pedopenna had dromaeosaur-like hind wings, and the fact that even primitive dromaeosaurs had fully developed wings, I don't think there is any uncertainty that all dromaeosaurs had feathers, at least to some extent. Even the few researchers who still believe that birds are not theropods include dromaeosaurids as birds, not dinosaurs. This sentence is misleading. Dinoguy2 20:46, 8 December 2005 (UTC)

[edit] "Almost Certain"

From history: 20:36, 26 January 2006 Kazvorpal "almost certain", let's be real. That's a ridiculously strong statement for almost any paleontological premise which lacks hard evidence) At what point will it be certain, then? When we discovery every sub-species of dromaeosaur and confirm that they had feathers? The fact is that very few skin impressions of early birds are known, and every single one has feathers. Why dromaosaurs should get a qualifier simply because they used to be thought of as more basal reptiles is beyond me. Were some naked? It's remotely possible, but even naked mammals today still have some hair (humans, mole rats, elephants, rhinos).

So, while not technically incorrect, it is very misleading. I propose either using "almost certain", omitting the general discussion of feathers altogether since it is taken for granted that they were present, or adding the phrase "it is entirely plausible that all __________ bore feathers of some type" on the entries for Confuciusornis, Hesperornis,Dromornithidae, Moa, and any other bird species which do not preserve fossil feathers.The Thagomizer 21:11, 26 January 2006 (UTC)

Your phrasing implies that there's significant evidence of many dromaeosauridae having feathers, but there is not. In fact, ONLY microraptors have hard evidence of being feathered. There is not a single, vague impression of a feather belonging to any other Dromaeosaur. Not one. To conclude, because a subset with a very exclusive range of traits has feathers, they ALL must have feathers is a huge leap. It's entirely possible that they did...in fact, even their more distant relatives, like the T-Rex, may have (though T-rex skin impressions have so far been scaley)...but it's also significqantly possible that the feathers were SOLELY a trait of microraptors.

In fact, one can almost see the desire to make such a completely unsupported statement as "almost certain" as being a preemptive defense of a very weak premise. Kaz 17:49, 28 January 2006 (UTC)

You don't seem to understand. Every single maniraptor ever found with any kind of skin impressions have shown feathers. None have shown scales (exept on the feet), or naked skin. At present there is no good reason to believe any maniraptor lacked feahter,s and you have yet to present one. Absence of evidence is not evidence of absence. I could see the argument here if you were a creationist, but to believe dromaeosaurs lacked feathers simply becasue we haven't found them on all species yet implies a severe lack of knowledge about how evolution works. Let me illustrate- you wrote "it's also significqantly possible that the feathers were SOLELY a trait of microraptors". If this is true, then feahters evolved multiple times in different branches of dinosaurs. It implies that dinosaurs evolved feahters at the Sinosauropteryx grade, retained them up through oviraptorosaurs and therizinosaurs, then they LOST feathers (and re-evolved scales or something...?), then Microraptorians evolved feahters *again*, and then birds also evolved feahters *again*. Your premise would have a very specific structure evolve not once but three times in very closely related animals. That's rediculous. There's no evidence to suggest feahters didn't evolve one, in compsognathids, and then stay there in all lineages all the way up to birds.The Thagomizer 00:46, 29 January 2006 (UTC)

Also, you ignored my point in my earlier post. You said-"Your phrasing implies that there's significant evidence of many dromaeosauridae having feathers, but there is not." There is zero evidence of any kind that Hesperornis had feathers either. Why is this case any different?The Thagomizer 00:49, 29 January 2006 (UTC)

Are you claiming that there are feather impressions for the ancestors of the Deinonychosauria and Oviraptorosauria? As far as I know, ONLY microraptors, of the dromaeosauria, have been found with feather impressions. It's quite a leap to assume that just because some microraptoria were around before Velociraptor mongoliensis, they must therefore have been their ancestors. The premise that a fully winged bird devolved its wings and become a predator with fully adapted front legs is at best an interesting supposition, with no hard evidence that I know of.

In fact, that's really what you need to do here; present some links to some serious science saying that fully winged, flying raptors were the ancestors of the big, terrestrial dromaeosaurs like deinonychus and mongoliensis. Not that they're more primitive or were around first, but are actual ancestors. It's far more likely that they were separate offshoots.

It is, by the way, entirely plausible for relatives within a group to separately evolve a similar trait, because of course the traits tend to be within the genome, but simply "turned off" by default. Kaz 03:28, 30 January 2006 (UTC)

"Are you claiming that there are feather impressions for the ancestors of the Deinonychosauria and Oviraptorosauria?" Yes, Yixianosaurus is a basal maniraptoran, and furthermore, Pedopenna is not only a basal Paravian (an ancestor of birds and deinonychosaurs) but it shouws the same type of feathers as Microraptorians, suggesting that the entire group evolved from microraptor-like ancestors.

• BZZZZZ...wrong. Utahraptor is as old as Yixianosaurus, and more than ten times its size. There's no reason, whatsoever, to assume Utahraptor had feathers. It may even be specifically unlikely.

This shatters your entire Original Research about all dromaeosaurs being descended from microraptors AND being almost certainly feathered. --Kaz 17:26, 31 January 2006 (UTC)

You're using the flase chronoly argument that the anti-birds-are-dinosaurs crowd used to use (before they decided that droameosaurs are birds). Just because Utahraptor is older does not mean it did not evolve from earlier microraptor-like ancestors (which exists in Archaeopteryx anway). An analogy is chimps and humans. Human evolved from the chimp family, yet chimps arealive today, and if humans were to go extinct, chimps would be around *after* their descendants! Studies show that, despite being around later, microraptors are more primitive than Utahraptor. This is possible because the fossil record is incomplete. Microraptorians MUST have existed before Utahraptor (or else all the research on these animals or their time periods is wrong), we just haven't found them yet. The presence of troodontids and dromaeosaurs in the Jurassic implies this, as does all morphological data. I cite these claims in the article. If you have published sources stating otherwise, please cite them. I have sources, you don't seem to, so you are engaging in original reseach.Dinoguy2 18:21, 31 January 2006 (UTC)

Utahraptor certainly descended from some ancestor...to assume that it was a feathered microraptor is ridiculous, since no evidence of microraptors exists before Utahraptor. Both could easily have evolved from a common ancestor, which may or may not have been feathered. And archaeopteryx was almost identical to compsognathus, not a raptor at all. It's entirely possible that microraptors and the archeopteryx-type birds were an example of parallel evolution.

"...the new feathered fossils are from a time after that of Archaeopteryx, the first bird (which lived about 147 million years ago, before Caudipteryx and Protarchaeopteryx). This suggests that perhaps the fossils' resemblance to birds could be a case of convergent evolution and that their feathers evolved for insulation, not flight, indicating a warm-blooded physiology.[2] "

Oh, and you are...not surprisingly...wrong about chimps. Humans did not evolve from "the chimp family", chimps are "devolved" homonids. Our common ancestor looked more like a human than chimps do. Chimps are a new ape from hominids, not a remainder of our ape ancestor.Kaz 19:32, 31 January 2006 (UTC)

Where are you getting this information about "devolved" chimps? I've studied anthropology and never come across this idea. Do you have a cite? As for the whole common ancestor and feathers issue, I don't know what to tell you. All the arguments about how we can infer the nature of common ancestry, figure ou relationships, etc comes from phylogenetics analyses with cladistics, and you obviously either reject these principals or don't understand them. Look- Utahraptor and Microraptor share a common ancestor with each other that is not shared with, say, Jinfengoptertyx. That's what defines the clade dromaeosauridae. If this common ancestor was NOT feathered, it means Microraptor evolved feathers independantly of Jinfengopteryx. It also means that almost *every single* other known feathered maniraptor evolved feathers with a central rachis, vanes, barbs, etc, independently of each other. This is simply an implausbly enormous amount of convergance. What makes the feathers of Miroraptor distinc from other dinoaurs, to the point where you assume they must have evolved seperately? The web site you link to proposes that the morphological similarities to birds are convergant, not the presence of feathers. No scientist has ever proposed that avian-style feathers evolved more than once. You need to find a paper that says otherwise. If you want to claim that Utahraptor lacked feathers, you need a cite for that too, since all available evidence from other maniraptors show feathers and ZERO show otherwise.Dinoguy2 20:20, 31 January 2006 (UTC)

"And archaeopteryx was almost identical to compsognathus, not a raptor at all. " If you'll look in any relevent literature publushed since te 1970s, you'll see that Archaeopteryx is only diffeentrom dromaeosaurs in trivial aspects, and profoundly different from compsognathids. A quick glance at the skeleton will show this. The tail is stiffened by rods, like dromies and unlike compies, the arms are long, with long feather-supporting digits (GSP goes into the characteristics of feather-bearing 2nd digits in DoA, showing that dromaeosaurs have this as well), unlike the very short, stout forelimbs of compsognathids. Features of the shoulder girdle (possibly adaptations for flight, see Paul and Mackovicky, etc) are shared by Archaeopteryx and dromaeosaurs and not Compsognathids. The hyperextendible second toe of Achaeopteryx, dromaeosaurids, and troodontids are obviously not present in compsognathids (an exhastive anatomical overview of Archaeopteryx and its similarities to droameosaurids can be found in Paul, 2002). No phylogenetic analysis has ever found a close relationship between Archie and compsognahtus. You're probably remembering the widely-known story of one Archie specimen that was initially mistaken for compsognathus, a spcimen which was very fragmentary to begin with, and as soon as it was looked a closely, the obvious mistake was caught.Dinoguy2 20:44, 31 January 2006 (UTC)

"The premise that a fully winged bird devolved its wings and become a predator with fully adapted front legs" Nobody is claiming that dromaeosaurs "devolved" their wings, their forearm structure is *exactly the same* as that of Archaeopteryx! "Not that they're more primitive or were around first, but are actual ancestors." First of all, cladistics assumes that we will never find actual ancestors. It displays relationships as sister gropus, and whether one sister group is the direct ancestor of another can't be known for certain without DNA evidence (obviously impossible for dinosaurs). "In fact, that's really what you need to do here; present some links to some serious science saying that fully winged, flying raptors were the ancestors of the big, terrestrial dromaeosaurs like deinonychus and mongoliensis." Some of those citations are already in the article. For example, Makovicky 2005 finds Rahonavis (a sickle-clawed, non-microraptorian dinosaur that nobody doubts could fly) to be an ancestral Unenlagian, and they find Unenlagiinae to be a subgroup of dromaeosauridae. Therefore we have Rahonavis and Microraptorians as *primitive* dromaeosaurs giving rise to the ground-dwelling later forms (this paper suggests that dromies became flightless *twice*, first the standard dromaeosaurs in the norths, then the unenlagiines in the south). Gregory Paul presents further evidence in Dinosaurs of the Air (2002) that Archaeopteryx is more primitive than/ancestral to dromaeosaurs, and this is supported by the sickle-clawed "Thermopolis specimen" discovered last year. One or two more finds like this and paleontologists will most likely make droameosaurs a sub-family within Archaeopterygidae and then we'll have to move them out of Dinosauria here and into Aves. Either way, here's a challange for you. Go onto the Dinosaur mailing List and ask any paleontologist there whether they think dromaeosaurs had feathers. Even the scientists who think birds are NOT dinosaurs think that dromaeosaurs and oviraptorosaurs are birds and not dinosaurs. I gauruntee you no serious scientist will disagree with "almost certain".The Thagomizer 14:36, 30 January 2006 (UTC)

Oh, and I keep forgetting to remind you of Jinfengopteryx, a short-armed, ground-dwelling deinonychosaur that didn't magically lose its feathers when it lost flight (if its ancestors indeed flew). To think that oviraptors, troodonts, unenlagiines, microraptorians, basal paravians, and basal maniraptorans were feathered while somehow only dromaeosaurids proper were not is, again, laughable.The Thagomizer 14:43, 30 January 2006 (UTC)

Kazvorpal maintains, on his talk page, that we should allow for the possibility that raptors never had feathers in their evolutionary history. Therefore, the feathers found in each of the various maniraptor lineages would not be homologous with one another, that is, feathers would have had to evolve independently at least 6 times. I've thrown together a handy chart to illustrate this point. It shows the relationships between maniraptoran dinosaurs and is color-coded. I'm not sure I can make it any more clear than this. The likelyhood that dromaeosaurines never had feathers is equal to the likelyhood that Hesperornis never did. Furthermore, if feathers had evolved seperately in each blue lineage, as Kaz's hypothesis requires, there should be some difference in their structure, when published studies show that they are homologous. Note that this is not original research, I've already cited most of the relevent papers in the article. Another important source is Prum and Brush, 2002 (Prum, R. & Brush A.H. 2002. The evolutionary origin and diversification of feathers. The Quarterly Review of Biology 77: 261-295.)Dinoguy2 14:33, 1 February 2006 (UTC)

Your chart, itself, is surely original research...I'd hope that no serious paleontologist would be either sloppy or ignorant enough to put Yixianosaurus, which lived 125 million years ago, near the base of the tree and then the Dromaeosarinae in question at the very end of one branch when one of their representatives, Utahraptor, lived...get this...125 million years ago.

It was contemporaneous with Yixianosaurus, which on your chart is THE first, genetically, example of fossil feather impressions. Which means that Utahraptor, which was TWENTY FEET LONG, and probably lacking in feathers, was almost certainly divergent from your first feathered example. Then again, the entire tree seems misarranged. Why is archeopteryx listed as being descended from creatures which lived millions of years after it? It may have been around as many as 150 million years ago, and some of its "ancestors" are more recent than that. --Kaz 06:10, 22 February 2006 (UTC)

I suggest you read up on cladistics before continuing in this discussion, it is obvious you don't know how to read a simple cladogram. That's what this is, a cladogram, not a phylogram (which shows relationships over time including ghost lineages). A cladogram shows genetic relationships inferred from morphology and independent of time. Yixianosaurus at the base of maniraptora does not mean it was *earlier*, it means it was *more primitive*. For example, the ancestor of humans and lemurs was primitive and lived in the beginning of the cenozoic. Yet the primitive lemurs still exist today, along side humans, just as the primitive Yixianosaurus still existed alongside the more advanced Utahraptor. This is better illustrated with your archaeopteryx example. Archie lived in the LJ. The probably more primitive Utahraptor lived in the EK. Troodontids, which were equal in advancement to both, lived in the MJ. Therefore, the ancestor of all three must have lived *at least* in the MJ, and we just haven't found remains of the transitional forms from back then. "the entire tree seems misarranged" My tree is identical to every dinosur family tree in every dinosaur book I own bublished since the 80s. I'm looknig through them now. The only difference is that new species have been added, and their positions are based on published research. Have you even read a *book* on dinosaurs, let alone a scientific paper, or are you just making stuff up?Dinoguy2 13:50, 22 February 2006 (UTC)

Ok, I've made two phylograms to hopefully make this more clear. This one [3] is the traditional view of maniraptor relationships over time. Blue represents known specimen ranges, dark blue is for groups that lack feather impressions. (Please excuse the crudity of this model, I didn't have time to make the individual stages to perfect scale). The second one [4] is only fully accepted by a few scintists, like Greg Paul, but I prefer it as it more closely matches the timeline and evidence we have at the moment. Note that in the second chart, if correct, all maniraptors except Yixianosaurus (which should have a "?" since Paul didn't include it) are true birds, being more advanced than Archaeopteryx. Dinoguy2 14:49, 22 February 2006 (UTC)

And just to make sure you know i'm not making this up, here's Paul Sereno's phylogram [5], Mickey Mortimer's cladogram [6], a cladogram from Jeff Poling's Dinosauria.com [7], and a cladogram from little kid's site Enchanted Learning [8] Here's a site from the AMNH on how to read a cladogram [9]. And just for your own edification, here's a google image search on "cladogram dinosaurs" [10], try to find one that differs from mine.Dinoguy2 15:12, 22 February 2006 (UTC)

[edit] Microraptoria

I just removed: Discussion about the relationship between birds and dinosaurs has mostly narrowed to whether bird ancestors lie within Dromaeosauridae or not. In order to exclude them, one recent cladistic analysis (Senter, 2004) has gone so far as to remove these three genera from Dromaeosauridae in the strict sense, and the authors created a new closely related taxon Microraptoria for them. Thus under this re-classification, it can still be claimed that there have been no reports of fossil feathers in Dromaeosauridae. This is not the case. Senter named the clade Microraptoria because, while he found them to be a subfamily in dromaeosauridae, there's a fair possibility that this will change in futture phylogenies. Thereofre, he used a non-family ending just in case (-ia instead of -inae). This was not a concious decision to "remove" them from dromaeosaurs, just an admission that they might remove themselves naturally with more evidence.The Thagomizer 01:01, 29 January 2006 (UTC)

Also, the only published phylogenetic definition of Dromaeosauridae is the last common ancestor of Velociraptor and Dromaeosaurus, plus all descendants. This almost certainly excludes microraptorians, unenlagiines, etc. Most of the content on this page should probably be relocated to Deinonnychosauria, but that's a big task, and many researchers do use the family as if it includes everything closer to Dromaeosaurus than to Aves or Troodon, even though that definition has never, to my knowledge, been published.--TMKeesey

[edit] Class

If dromaeosaurids are indeed true birds, which seems to be the current paleontological consensus, then why are they all listed under Class Sauropsidia and not Class Aves? Crotalus horridus (TALK • CONTRIBS) 05:22, 3 March 2006 (UTC)

It's a reletevile new hypothesis, and has not been published in many science journals. Even though at least two published papers find that Oviraptorosaurs are true birds, we're holding out on putting them in class Aves until something closer to a majority of scientists supports that idea. Same with dromaeosaurs--best just to mention the possibility, and wait for more evidence before actually changing anything.Dinoguy2 14:01, 3 March 2006 (UTC)

Yet another excellent case for using clade lists instead of (or at least alongside) Linnaean categories.--TMKeesey