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Author Topic:   Archaeopteryx and Dino-Bird Evolution
arachnophilia
Member (Idle past 1344 days)
Posts: 9069
From: god's waiting room
Joined: 05-21-2004


Message 46 of 200 (289334)
02-21-2006 6:52 PM
Reply to: Message 45 by Mallon
02-21-2006 11:34 AM


drepanosaurs? is feduccia nuts?
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 That book is terribly out of date, mind you.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 i imagine it probably is a bit out of date -- it was written in 1988.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


This message is a reply to:
 Message 45 by Mallon, posted 02-21-2006 11:34 AM Mallon has replied

Replies to this message:
 Message 47 by Mallon, posted 02-21-2006 7:01 PM arachnophilia has not replied

  
Mallon
Inactive Member


Message 47 of 200 (289337)
02-21-2006 7:01 PM
Reply to: Message 46 by arachnophilia
02-21-2006 6:52 PM


Re: drepanosaurs? is feduccia nuts?
quote:
ok, that just makes my brain hurt. how are deinonychosaurs NOT theropods?
If you ever find out, let me know! The answer is beyond fathom.

This message is a reply to:
 Message 46 by arachnophilia, posted 02-21-2006 6:52 PM arachnophilia has not replied

  
arachnophilia
Member (Idle past 1344 days)
Posts: 9069
From: god's waiting room
Joined: 05-21-2004


Message 48 of 200 (289341)
02-21-2006 7:12 PM
Reply to: Message 45 by Mallon
02-21-2006 11:34 AM


Re: more on longisquama
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:
There are no feather-like features on the distal portion of the appendage. Here, two corrugated membrane-like surfaces touch along their leading and trailing edges to form wide, smooth bands. The two membranes were apparently supported by a median veinlike structure extending the length of the appendage. This has been proposed as the homologue of the rhachis of avian feathers2. On either side of this ”vein’, the external surfaces of the appendage are corrugated. This corrugation varies along the appendage: proximally, individual rugae are relatively large and widely spaced, but in the distal portion they are smaller and densely packed. The densely arranged distal corrugations have been compared to the pinnae of avian feathers2, but the fossils indicate that these are formed on a membrane-like structure on either side of the ”vein’.
The fossils were split into part and counterpart during collecting, and most of the appendages are now preserved as impressions of their left and right sides, without the intervening sediment core. The surfaces of both the part and counterpart impressions of individual appendages are concave, an indication that these structures are three-dimensional. In contrast, the parts and counterparts of feather impressions in Archaeopteryx are concave and convex, respectively.
We believe that the dorsal appendages of Longisquama are highly modified scales, as suggested previously1,3, rather than feathers.
Examination of the holotype of L. insignis (PIN 2584/4) suggests that they were anchored in the skin or epaxial muscles.
1. Sharov, A. G. Paleontol. Zhur. 1970, 127-130 (1970).
2. Jones, T. et al. Science 288, 2202-2205 (2000).
3. Feduccia, A. The Origin and Evolution of Birds (Yale Univ. Press,
New Haven, 1996).
http://www.utm.utoronto.ca/~w3reisz/pdf/Longis.pdf
he seems to say that feduccia says they are highly modified scales, not feathers. maybe i should track down feduccia's paper too...


This message is a reply to:
 Message 45 by Mallon, posted 02-21-2006 11:34 AM Mallon has not replied

  
AdminBuzsaw
Inactive Member


Message 49 of 200 (289344)
02-21-2006 7:24 PM
Reply to: Message 17 by jar
10-10-2005 9:20 PM


Re: Inadequate support for an assertion
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

This message is a reply to:
 Message 17 by jar, posted 10-10-2005 9:20 PM jar has replied

Replies to this message:
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AdminBuzsaw
Inactive Member


Message 50 of 200 (289347)
02-21-2006 7:35 PM


New Posters Welcome
I see some fairly new members here in this thread. We welcome you to EvC Forums. Thanks for our input.

  
jar
Member (Idle past 394 days)
Posts: 34026
From: Texas!!
Joined: 04-20-2004


Message 51 of 200 (289349)
02-21-2006 7:43 PM
Reply to: Message 49 by AdminBuzsaw
02-21-2006 7:24 PM


Re: Inadequate support for an assertion
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

This message is a reply to:
 Message 49 by AdminBuzsaw, posted 02-21-2006 7:24 PM AdminBuzsaw has not replied

Replies to this message:
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arachnophilia
Member (Idle past 1344 days)
Posts: 9069
From: god's waiting room
Joined: 05-21-2004


Message 52 of 200 (289350)
02-21-2006 7:47 PM
Reply to: Message 51 by jar
02-21-2006 7:43 PM


both of you go away
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


This message is a reply to:
 Message 51 by jar, posted 02-21-2006 7:43 PM jar has replied

Replies to this message:
 Message 53 by jar, posted 02-21-2006 7:49 PM arachnophilia has not replied

  
jar
Member (Idle past 394 days)
Posts: 34026
From: Texas!!
Joined: 04-20-2004


Message 53 of 200 (289354)
02-21-2006 7:49 PM
Reply to: Message 52 by arachnophilia
02-21-2006 7:47 PM


Re: both of you go away
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

This message is a reply to:
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arachnophilia
Member (Idle past 1344 days)
Posts: 9069
From: god's waiting room
Joined: 05-21-2004


Message 54 of 200 (289640)
02-22-2006 9:07 PM
Reply to: Message 45 by Mallon
02-21-2006 11:34 AM


speaking of velociraptors
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:
V. mongoliensis (and deinonychosaurs in general) is most revered for its two sickle-shaped claws, each of which extended from the second toe of the hind foot. It could latch onto inauspicious prey with its grasping hands and use these talons to kick into the bellies of its victims, cutting deep lacerations into the animal's flank (Paul, 1988).
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:
One of the most complete skeletons of V. mongoliensis was found intertwined with the remains of Protoceratops andrewsi, an early horned dinosaur. The fossilized specimen, commonly referred to as the "fighting dinosaurs," reveals that the two contenders died in combat; the predator's hind foot embedded in the thorax of its victim, while having its own arm bitten in turn (Glut, 1997; Novacek, 1996). It is not known exactly why these animals were fighting, although recent evidence suggests that the victims died as a result of an intense rainstorm (Novacek, 2002).
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


This message is a reply to:
 Message 45 by Mallon, posted 02-21-2006 11:34 AM Mallon has replied

Replies to this message:
 Message 55 by MangyTiger, posted 02-22-2006 9:40 PM arachnophilia has replied
 Message 57 by Mallon, posted 02-23-2006 9:41 AM arachnophilia has replied

  
MangyTiger
Member (Idle past 6354 days)
Posts: 989
From: Leicester, UK
Joined: 07-30-2004


Message 55 of 200 (289642)
02-22-2006 9:40 PM
Reply to: Message 54 by arachnophilia
02-22-2006 9:07 PM


Re: speaking of velociraptors
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

This message is a reply to:
 Message 54 by arachnophilia, posted 02-22-2006 9:07 PM arachnophilia has replied

Replies to this message:
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arachnophilia
Member (Idle past 1344 days)
Posts: 9069
From: god's waiting room
Joined: 05-21-2004


Message 56 of 200 (289653)
02-22-2006 11:08 PM
Reply to: Message 55 by MangyTiger
02-22-2006 9:40 PM


the bbc and "walking with dinos"
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


This message is a reply to:
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Mallon
Inactive Member


Message 57 of 200 (289733)
02-23-2006 9:41 AM
Reply to: Message 54 by arachnophilia
02-22-2006 9:07 PM


Re: speaking of velociraptors
quote:
now, i don't mean to call you on this to be rude or anything
It's not rude at all. I always appreciate it when someone points out my mistakes. I invite it on my site.
quote:
a recent study showed that velociraptor claws would have been poor slicing blades.
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).

This message is a reply to:
 Message 54 by arachnophilia, posted 02-22-2006 9:07 PM arachnophilia has replied

Replies to this message:
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arachnophilia
Member (Idle past 1344 days)
Posts: 9069
From: god's waiting room
Joined: 05-21-2004


Message 58 of 200 (289845)
02-23-2006 3:52 PM
Reply to: Message 57 by Mallon
02-23-2006 9:41 AM


Re: speaking of velociraptors
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.


This message is a reply to:
 Message 57 by Mallon, posted 02-23-2006 9:41 AM Mallon has not replied

Replies to this message:
 Message 59 by jar, posted 02-23-2006 4:05 PM arachnophilia has replied

  
jar
Member (Idle past 394 days)
Posts: 34026
From: Texas!!
Joined: 04-20-2004


Message 59 of 200 (289846)
02-23-2006 4:05 PM
Reply to: Message 58 by arachnophilia
02-23-2006 3:52 PM


coloration
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

This message is a reply to:
 Message 58 by arachnophilia, posted 02-23-2006 3:52 PM arachnophilia has replied

Replies to this message:
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arachnophilia
Member (Idle past 1344 days)
Posts: 9069
From: god's waiting room
Joined: 05-21-2004


Message 60 of 200 (289851)
02-23-2006 4:16 PM
Reply to: Message 59 by jar
02-23-2006 4:05 PM


Re: coloration
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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 Message 59 by jar, posted 02-23-2006 4:05 PM jar has not replied

Replies to this message:
 Message 61 by DBlevins, posted 02-23-2006 5:27 PM arachnophilia has replied

  
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