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Member (Idle past 2521 days) Posts: 2965 From: Los Angeles, CA USA Joined: |
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Author | Topic: Archaeopteryx and Dino-Bird Evolution | |||||||||||||||||||||||
arachnophilia Member (Idle past 1372 days) Posts: 9069 From: god's waiting room Joined: |
You're right in saying the dromaeosaurid line did not produce birds. It is commonly argued that the deinonychosaurs (dromaeosaurids + troodontids) are the sister taxon to the birds. my opinion is that either the ancestor of dromeosaurs, or a very early dromeosaur spun off into birds, but that the dromeosaurs we commonly associate with the group (velociraptor, deinonychus, and maybe even archie) are from the "dinosaur" line, not the "bird" line.
But maybe after reading Paul's book, you will change your mind. That book is terribly out of date, mind you. I'm just impressed that you were able to pick up PDW at a used book store -- that thing is very hard to come by. i was suprised, too. the amount of actual data and reconstructions in it is just incredible. i imagine it probably is a bit out of date -- it was written in 1988. but it does seem to be of quite modern thought, at least. there's lots of depictions and reconstructions that show running, warm blooded, and feathered dinosaurs. obviously, it couldn't have incorporated the very recent discovery that tyrannosaurids had feathers. but that's science: always changing and updating itself. amazingly, it was MORE up-to-date than another newer book i looked at, and a fraction of the price.
Is it any wonder creationists continually cite him for support? ...well, actually, it kind of. granted, they cite ANYONE who disagrees with mainstream evolutionary theory, but in the process they tend to prop up people who still obviously understand something about evolution. feduccia is NOT saying that birds were created, or didn't evolve. he's saying they evolved from something besides theropod dinosaurs. it's just an excuse to write off archaeoptryx as "not a transitional species."
I think he has even changed his tune now and argues that neither birds NOR deinonychosaurs are theropods, but evolved instead from a drepanosaurid-like ancestor. There was a paper on this recently... ok, that just makes my brain hurt. how are deinonychosaurs NOT theropods? granted, drepanosaurids are another oddity. i mean, if someone looked at ONLY the skull and neck of one, they might see some similarity to birds, especially in megalancosaurus (the other "ridiculous" example i mentioned above). but the rest of the body is pretty typical lizard. i mean, if i had to pick an ancestor for this guy: would i go with: or? birds aside, the ancestry of deinonychosaurs is, um, blindingly obvious. his changing his tune to include deinonychosaurs (if true) is an obvious sign that EVEN feduccia recognizes the similarity between birds and dromeosaurs.
If memory serves me, the Reisz paper is available on his lab website for download. ok, i'll look a little harder edit: found it, i'll give it a read. This message has been edited by AdminJar, 02-21-2006 05:55 PM This message has been edited by arachnophilia, 02-21-2006 06:57 PM
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Mallon Inactive Member |
quote:If you ever find out, let me know! The answer is beyond fathom.
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arachnophilia Member (Idle past 1372 days) Posts: 9069 From: god's waiting room Joined: |
If memory serves me, the Reisz paper is available on his lab website for download. that was a much shorter article than i expected. here's the important part of the article:
quote: he seems to say that feduccia says they are highly modified scales, not feathers. maybe i should track down feduccia's paper too...
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AdminBuzsaw Inactive Member |
Jar, my friend, this is not a sufficient response to AdminNosy. You need to either refrain from these kinds of comments or bring forth a substantive response as to why you think it is bogus (better word than crap) . You know we don't let folks like Randman do stuff like this so to be fair and balanced, I suggest that you either offer an apology or post a substantial response (abe: with reasons why you think it is false). Thanks.
This message has been edited by AdminBuzsaw, 02-21-2006 07:38 PM
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AdminBuzsaw Inactive Member |
I see some fairly new members here in this thread. We welcome you to EvC Forums. Thanks for our input.
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jar Member (Idle past 422 days) Posts: 34026 From: Texas!! Joined: |
Off Topic response removed and moved to the proper forum.
This message has been edited by jar, 02-21-2006 06:56 PM Aslan is not a Tame Lion
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arachnophilia Member (Idle past 1372 days) Posts: 9069 From: god's waiting room Joined: |
jar, it was quite a waste of space for a post (even four months ago). no real argument. you'll noticed i posted a very lengthy and detailed refutation of his points. a post of "crap!" doesn't do much for the argument, either way.
and we've got some interesting bird evolution discussion going here right now. you know where to take administration complaints. This message has been edited by arachnophilia, 02-21-2006 07:47 PM
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jar Member (Idle past 422 days) Posts: 34026 From: Texas!! Joined: |
You are correct. I should not have responded here. My apology. It does not belong here. I will edit my response to move it elsewhere.
Aslan is not a Tame Lion
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arachnophilia Member (Idle past 1372 days) Posts: 9069 From: god's waiting room Joined: |
i was poking around your site, and i noticed some of that outdated information from the gregory paul book i'm reading show up:
quote: now, i don't mean to call you on this to be rude or anything -- this is a pretty persistent idea and probably still very debatable. but i'd like to make an argument, on topic to this thread, about possible deinonychosaur hunting methods. a recent study showed that velociraptor claws would have been poor slicing blades. i think these were the same guys who did a similar study on the teeth of sabre-toothed cats. in both studies, they made the case that these similarly-shaped weapons were good at precision puncturing, not tearing or slicing. if we think about it for a second, it makes sense. nearly every other theropod hunted with its teeth, and used them to tear out a large gouge in the prey. they would probably circle and wait for the prey to die, like sharks do. their teeth are designed for slicing, like knives. but deinonychus does something different. it hunts with it's feet, as well as (maybe) its teeth. two basic bits i think everyone agrees on. 1) that the claws were hunting weapons, not dominance-fighting weapons. too much risk in breaking such a large claw. 2) to use them, deinonychosaurs had to be airborn. now, if we compare a velociraptor skeleton to our friend archaeopteryx, we find lots of similarities. enough that most people now consider it a dromaeosaur. we also have the raptor named after paul, which is even more closely related. both have full flight-feathered, lift-generating wings. both (iirc) lacked the ability to fly. the study above suggests that velociraptors used precision, and went for the jugular. this approach makes more sense over the brute-force "gut the victim" idea for such a small animal. the claws, aimed correctly, would deliver a fast, fatal, and low-contact wound to the prey. there is actually evidence supporting this idea, too. modern raptors hunt with their feet, in a similar, precise way. and the famous velociraptor/protoceratops fight scene:
quote: the velociraptor has its claw hooked into the protoceratops' neck, as this picture shows. i'd like to make an additional suggestion: that deinonychosaurs had lift-generating wings, which they would use to assist in jumping attacks, slow air-speed for precision kills, and intimidate/distract prey from biting important parts of their bodies. this is probably why the protoceratops has grabbed onto an arm: he got lucky and found a bone amid all the feathers. i would imagine that the wings were probably also brightly colored to draw the victims attention (presuming color vision in the prey, anyways). it would make for good maiting/rivalry displays, too. anyways, think this is a reasonable idea? i'm not well versed enough in the area to know some of the specifics of arm anatomy and movement. what do you think? could raptors "flap?" This message has been edited by arachnophilia, 02-22-2006 09:10 PM
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MangyTiger Member (Idle past 6382 days) Posts: 989 From: Leicester, UK Joined: |
a recent study showed that velociraptor claws would have been poor slicing blades. A two part TV show (The Truth About Killer Dinosaurs) with one of the episodes based on this work was shown over here in August/September last year. It was reasonably interesting but a bit dumbed down for my taste, like all recent BBC shows with any science content. The Beeb appears to have taken a policy decision not to produce science shows as such any more, rather it produces entertainment shows with a fairly minimal amount of science in them I wish I didn't know now what I didn't know then
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arachnophilia Member (Idle past 1372 days) Posts: 9069 From: god's waiting room Joined: |
A two part TV show (The Truth About Killer Dinosaurs) with one of the episodes based on this work was shown over here in August/September last year. It was reasonably interesting but a bit dumbed down for my taste, like all recent BBC shows with any science content. The Beeb appears to have taken a policy decision not to produce science shows as such any more, rather it produces entertainment shows with a fairly minimal amount of science in them there was one i saw recently, as a spin off from "walking with dinosaurs." it was all about one specific allosaurus fragilis specimen, and the life it led. it had considerably more science content than i was expecting. they showed the actual skeleton (gasp!) and examined the various evidences of wounds. they explained how they how old (from time of death) each was, too. in fact, they gave some half-decent science backing for nearly everything they said. still quite dumbed-down of course. but a vast improvement over "walking with dinosaurs." i think it was an effort to say "we're not making this stuff up wholesale." i dunno, it's like they think poking around in the sand and chiselling rock all day under the hot badlands sun isn't interesting or something. This message has been edited by arachnophilia, 02-22-2006 11:10 PM
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Mallon Inactive Member |
quote:It's not rude at all. I always appreciate it when someone points out my mistakes. I invite it on my site. quote:Yes, I'm familiar with the study. Just haven't really had the chance to update it on my website. In fact, to be honest, I forgot that I had written anything that implied the contrary of the study's findings. There's probably lots more on my site that is out of date (including my bio). I need to do a major content update. Otherwise, I agree with everything you say. Except the bit out Velociraptor having brightly coloured feathers to get the prey's attention. If you're a predator, I think the last thing you want to do is to get your prey's attention (that's what made those WWD shows such a tragedy -- the big theropods would run up to their prey, roaring all the while and scaring them away).
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arachnophilia Member (Idle past 1372 days) Posts: 9069 From: god's waiting room Joined: |
Otherwise, I agree with everything you say. Except the bit out Velociraptor having brightly coloured feathers to get the prey's attention. If you're a predator, I think the last thing you want to do is to get your prey's attention (that's what made those WWD shows such a tragedy -- the big theropods would run up to their prey, roaring all the while and scaring them away). yes, that's probably a good point.
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jar Member (Idle past 422 days) Posts: 34026 From: Texas!! Joined: |
But don't dismiss coloration entirely. There is also the possibility of vaiable coloration and uses. There could be colored feathers used as camouflage but others might be brighter and used for display and courtship.
Aslan is not a Tame Lion
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arachnophilia Member (Idle past 1372 days) Posts: 9069 From: god's waiting room Joined: |
well, sexual dimorphism is also a possibility. males could be brightly colored and females dull, or vice versa. i was also thinking of bright spots on the wings that would be concealed in stalking mode...
but short of "it's not good hunting strategy" it's really all idle speculation.
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