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Post by Horridus on Jul 27, 2011 17:17:46 GMT
Abstract from a new paper by Xu et al: " Archaeopteryx is widely accepted as being the most basal bird, and accordingly it is regarded as central to understanding avialan origins; however, recent discoveries of derived maniraptorans have weakened the avialan status of Archaeopteryx. Here we report a new Archaeopteryx-like theropod from China. This find further demonstrates that many features formerly regarded as being diagnostic of Avialae, including long and robust forelimbs, actually characterize the more inclusive group Paraves (composed of the avialans and the deinonychosaurs). Notably, adding the new taxon into a comprehensive phylogenetic analysis shifts Archaeopteryx to the Deinonychosauria. Despite only tentative statistical support, this result challenges the centrality of Archaeopteryx in the transition to birds. If this new phylogenetic hypothesis can be confirmed by further investigation, current assumptions regarding the avialan ancestral condition will need to be re-evaluated." Paper is here: www.nature.com/nature/journal/v475/n7357/full/nature10288.htmlNew Scientist have an article about it: www.newscientist.com/article/mg21128234.400-archaeopteryx-knocked-off-its-perch-as-first-bird.htmlNot too surprising really, but still quite a big deal. Thoughts? (Maybe Velociraptor will become a bona fide bird! I'm sure certain people will be delighted. Of course it all depends on whether other people agree with this conclusion.) |
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Post by itstwentybelow on Jul 27, 2011 17:48:00 GMT
Hmmmm I think they may be jumping the gun with this reclassification, but we'll see...
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Post by paleofreak on Jul 27, 2011 21:37:44 GMT
Not too surprising really, but still quite a big deal. Thoughts? (Maybe Velociraptor will become a bona fide bird! I'm sure certain people will be delighted. Of course it all depends on whether other people agree with this conclusion.) It depends on what definition of Aves are you following. If you follow Sereno 2005 (The least inclusive clade containing Archaeopteryx lithographica and Passer domesticus), or other similar definitions, then the new tree would make Velociraptor a member of Aves. |
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Post by dyscrasia on Jul 28, 2011 2:47:57 GMT
Xiaotingia zhengi  Kinda reminds me more of Anchiornis (which is reclassified as a member of Archaeopterygidae according to the paper / previously classified as a Troodontid)....
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Post by DinoLord on Jul 28, 2011 3:36:08 GMT
The leg feathers are wrong!  But I do wonder if the colors are speculative, or if they used the same pigment studying process they did for Sinosauropteryx and Anchiornis. |
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Post by arioch on Jul 29, 2011 13:10:41 GMT
Interesting finding...but I´m not really sold on the reclassification. So, now dromaeosaurs would be avian, but Oviraptorids and alvarezsaurs don´t? Why not reestructure the whole clade?
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Post by Griffin on Jul 29, 2011 17:42:16 GMT
I saw this in the paper. From what I read they said it could still be re-reclassified back to the way it was after they do some more research. I have no clue lol
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Post by Horridus on Jul 29, 2011 18:42:20 GMT
So, now dromaeosaurs would be avian This isn't what the paper said - the paper just said that, when including the new taxon in a systematic analysis, Archaeopteryx was shifted to the Deinonychosauria (from being a basal avian before). However, remove the new taxa and it's a basal avian again. The whole thing makes it clear that basal avians and basal deinonychosaurs are very hard to tell apart. Some people have proposed that 'birds' apply to Paraves as a whole. But no one's published on it yet. |
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Post by arioch on Jul 29, 2011 19:23:35 GMT
I think Archaeopteryx would still be considered a basal bird. We have no reason to think it actually wasn´t, right?
On the other hand I would be very happy if Paraves become part of aves. But again, would they leave out Oviraptorosaurs or alvarezsaurs? why not include in aves the whole maniraptora except maybe the more primitive comsognathids or ornitholestes?
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Post by Horridus on Jul 29, 2011 19:33:32 GMT
I think Archaeopteryx would still be considered a basal bird. We have no reason to think it actually wasn´t, right? On the other hand I would be very happy if Paraves become part of aves. But again, would they leave out Oviraptorosaurs or alvarezsaurs? why not include in aves the whole maniraptora except maybe the more primitive comsognathids or ornitholestes? Well, the latter two aren't maniraptorans. They're more basal coelurosaurs. Xu et al, by way of a cladistic analysis that includes the new taxon they described, do have reason to believe that Archaeopteryx is not a basal avian, but a basal deinonychosaur. However, with the new taxon removed Archaeopteryx reverts to being a basal avian. Either way, birds remain just another dinosaur group. Allow me to shamelessly self-promote: chasmosaurs.blogspot.com/2011/07/i-like-birds-o.html |
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Post by arioch on Jul 29, 2011 19:43:14 GMT
I think Archaeopteryx would still be considered a basal bird. We have no reason to think it actually wasn´t, right? On the other hand I would be very happy if Paraves become part of aves. But again, would they leave out Oviraptorosaurs or alvarezsaurs? why not include in aves the whole maniraptora except maybe the more primitive comsognathids or ornitholestes? Well, the latter two aren't maniraptorans. They're more basal coelurosaurs. Really? another wrong/outdated cladogram in wikipedia. How surprising. Already knew and enjoyed the blog. ;D |
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Post by Horridus on Jul 29, 2011 19:47:46 GMT
Just checked Wikipedia and Compsognathus and its ilk aren't there! I'll admit, Ornitholestes may be a basal maniraptor, according to some. (Forgot that, whoops...)
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Post by arioch on Jul 29, 2011 20:59:54 GMT
Its mentioned that compsognathids are sometimes included, though not very often...
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Post by paleofreak on Jul 30, 2011 0:09:02 GMT
However, with the new taxon removed Archaeopteryx reverts to being a basal avian. From being a basal avialian (Avialae). And the authors use a definition of Avialae that explicitly excludes the Deinonychosauria. With exactly the same tree, different authors could have yield different classifications, with Archie being an avian, and an avialian, and the "raptors" being avians too. |
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Post by neovenator08 on Jul 30, 2011 6:47:15 GMT
So if Archaeopteryx is a dromeosaur, what is the new earliest bird?
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bfler
Junior Member
Posts: 97
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Post by bfler on Jul 30, 2011 9:54:53 GMT
Why not simply switch Deinonychosauria to avians? The nothing would change, instead such a muddle.
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Post by dinoguy2 on Jul 30, 2011 14:55:36 GMT
So if Archaeopteryx is a dromeosaur, what is the new earliest bird? Depends on what you mean by bird. Aves was traditonaly defined to include Archaeopteryx by default. Now, scientists are starting to use Aves to mean only MODERN birds (Neornithes), and 'bird' itself to mean Avialae, which is why this headline is "Archaeopteyrx no longer a bird" and not "Velociraptor now classified as a true bird." If 'bird' means Avialae, then Epidexipteryx and Scansoriopteryx are the earliest known birds. If 'bird' means Aves, then the first birds is Gallornis, from the early Cretaceous. Why not simply switch Deinonychosauria to avians? The nothing would change, instead such a muddle. I agree, this would have been better and less confusing (and Xiaotingia would have gotten the title of first bird!). But theere seems to be some psychosis around the 'older' generation of paleontologists that says raptors must not ever been considered birds under any circumstances, and even if all available evidence and studies force us to admit that they are, we must therefore change the very meaning of the word 'bird' to avoid it! |
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Post by paleofreak on Jul 30, 2011 15:26:15 GMT
Now, scientists are starting to use Aves to mean only MODERN birds (Neornithes) scientists. Others use a bigger clade Aves, thus including the enantiornithes -and of course Archie. One example (but you could find lots): www.tandfonline.com/doi/abs/10.1080/14772019.2010.512614 |
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Post by Horridus on Jul 30, 2011 15:36:45 GMT
However, with the new taxon removed Archaeopteryx reverts to being a basal avian. From being a basal avialian (Avialae). Right, sorry. For some reason I had it in my head that the two are synonymous. Well, they sometimes are...depends on the definition being used. |
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Post by pylraster on Sept 17, 2011 16:12:29 GMT
Archaeopterix being not a bird doesn't really bother me lol. I never thought of dinosaurs as extinct anyway... I just had one for dinner at KFC. ^^
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But I do wonder if the colors are speculative, or if they used the same pigment studying process they did for Sinosauropteryx and Anchiornis.
