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Re: Archaeopteryx



Ivan Kwan wrote:
Throughout the history of discussions on dinosaur-bird relationships, almost every person comes to a foregone conclusion that _Archaeopteryx_ is THE first bird, with all the others (confuciusornithids, enantiornithes, _Iberomesornis_, _Eoalulavis_, _Shenzouraptor_, _Rahonavis_, etc) all falling behind it. It puzzles me that almost every cladogram I can think of relies very heavily on a species that is to date known by just 7 2-dimensional specimens & a single feather (tentatively referred to Archie as well.)


Hey, don't discount those 2-D specimens, they can be pretty useful at times. :-)


I'm very ignorant about all this avian cladistics & stuff, but consider this: what if we've been wrong all along? could it be that _Archaeopteryx_ was NOT the first bird? What if it was actually an 'aberrant' offshoot that evolved from maniraptors before the other birds branched off or was actually more derived than other so-called 'birds'? What if we eventually discover that 'birds' as we know them may be diphyletic or paraphyletic (unlikely, but what if we find out that some of the early birds turn out to be one lineage of dromaeosaurs that evolved more birdlike features?) Does _Archaeopteryx_ still retain its "first bird" status? Or what if others find that once & for all, that dromaeosaurs (or troodonts or oviraptorosaurs) actually evolved after Archaeopteryx split off the maniraptor lineage? Would that put the dinosaur-bird debate in a whole new perspective?


It really wouldn't change anything. Aves is defined most commonly as Archaeopteryx + Neornithes (or some neornithine species), so Aves would just expand and take on new taxa. It wouldn't be all that surprising if Rahonavis were found to be perhaps a derived dromaeosaurid or perhaps a basal one.


Somehow every phylogenetic analysis seems to assume that because _Archaeopteryx_ is the oldest bird discovered to date, it is the Ur-bird (_Protoavis_ notwithstanding). I think we need people to scrutinise every feature of _Archaeopteryx_ from every angle, to note every detail, and compare it with EVERY (and i mean every) other Mesozoic bird species & non-avian maniraptor.


When did phylogenetic analyses start incorporating assumptions about time? The only time this problem should occur is if the analysis were rooted on Archaeopteryx, to which I recall, none are.


I believe the disagreements on coelurosaur & avialan phylogeny will be around for quite a while, & I do hope that things get resolved as quickly as possible, but I just wish we had more specimens of _Archaeopteryx_ to give more solid proof that it is the "First" bird.


There probably were volant taxa more basal than Archaeopteryx, we just haven't found them yet. However, it is possible that Archaeopteryx truly is the first volant maniraptor, but it would be difficult to prove in my honest opinion.


Nick Gardner

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