RE: on-line fossil birds list

[Tim Williams <twilliams_alpha@hotmail.com>]

Ian Paulsen wrote:

> http://www.answers.com/topic/fossil-birds

My 2.5c, on the first few sections....

> Proto-birds
> Taxa usually considered to be non-avian feathered dinosaurs, but which may 
> be true birds.
>
> "Protoavis" (Late Triassic) - probably invalid

_Protoavis_ is perhaps a valid taxon, although the hypodigm widely regarded 
as a composite of two or more taxa - theropod(?), drepanosaurid(?), etc.  
Chatterjee's interpretation that _Protoavis_ is a bird (avian) more derived 
than _Archaeopteryx_ has not received much support.  Hardly any, in fact.  
That's not to say he's wrong, however.  _Protoavis_ requires further study.

> Alvarezsauridae

Most likely non-avian.  Derived alvarezsaurids like _Mononykus_ and 
_Shuvuuia_ show avian characters not seen in basal forms, like 
_Alvarezsaurus_ and _Patagonykus_

> Oviraptorosauria, Troodontidae, Dromaeosauridae

And therizinosaurs too.  The chances that these four groups are secondarily 
flightless (or at least had ancestors that were capable of some form of 
aerial locomotion) are about 50:50, IMHO.  However, this is different to 
saying that they belong in Aves (i.e., contained within the clade defined by 
_Archaeopteryx_ and modern birds).  The first is an ecomorphological 
hypothesis, the second is a phylogenetic hypothesis.

> Rahonavis (Late Cretaceous)

The phyogenetic analysis of Makovicky et al. (2005) certainly recovered 
_Rahonavis_ as a flighted dromaeosaurid, outside of Aves.  I doubt that this 
is the last word on _Rahonavis_'s relationships, however.

> Scansoriopterygidae, Epidendrosaurus (Early Cretaceous)

Might be Middle or Late Jurassic; this hinges on the age of the Daohagou 
Bed.  The affinities of _Scansoriopteryx_ and _Epidendrosaurus_ have yet to 
be pinned down with confidence.  The juvenile nature of the specimens do not 
help this cause.  You can certainly discount anything Czerkas and Yuan 
(2002) have to say on the topic.

> Yandangornis

At the current time, there's no reason to consider this *not* a bird.  The 
original description is not overly helpful in this regard.  Zhou and Zhang 
(2006) do not regard _Yandangornis_ as an avian, but do not elaborate on why 
not.

> Basal Aves
> The most primitive birds, usually still possessing a long bony tail with 
> generally unfused vertebrae.
>
> Unresolved forms Dalianraptor (Jiufotang Early Cretaceous of Liaoning, 
> China), Jixiangornis (Early Cretaceous),
> Shenzhouraptor (Early Cretaceous)

"Basal avian" seems to be about right for these guys.  Some taxononomic 
springcleaning is needed for this collection of long-tailed birds, given 
that _Jeholornis_ might actually be the valid name for _Shenzhouraptor_ 
(according to Zhou and Zhang [2006], who give reasons - 
http://dml.cmnh.org/2006Apr/msg00228.html); and _Jixiangornis_ may also 
prove to be referrable to this taxon.

> Hebeiornis (Yixian? Early Cretaceous? of Hebei, China)

Might be a _nomen nudum_.

> Hulsanpes (Late Cretaceous)

This critter was recently said to be a dromaeosaurid after all (I think I 
saw this in the _Atrociraptor_ description).

> Archaeopterygidae Archaeopteryx (Late Jurassic) Wellnhoferia (Late 
> Jurassic) - may be synonym of Archaeopteryx

Indeed.

> Omnivoropterygiformes
> Omnivoropterygidae Omnivoropteryx (Early Cretaceous)

Your guess is as good as mine.  Needs a proper description.

> Sapeornis (Jiufotang Early Cretaceous of Chaoyang City, China)

I wouldn't put _Sapeornis_ in Omnivoropterygidae etc quite yet.  This needs 
to be tested by phylogenetic analysis.

> ?Basal Pygostylia
> The earliest birds with a modern pygostyle: a reduction and fusion of the 
> tail vertebrae.
>
> Placement unresolved Abavornis (Late Cretaceous) - enantiornithine?, 
> Catenoleimus

No idea.

> "Paleopteryx"

_Palaeopteryx_ is known from a broken-off piece of the radius, which could 
come from a bird or a deinonychosaur.  The genus is valid in the 
nomenclatural sense (Jensen, 1981), but probably invalid in the taxonomic 
sense (i.e., it's a nomen dubium).  The specimen comes from the Late 
Jurassic of Colorado.

> Confuciusornithidae Proornis (Sinniju Late Jurassic/Early Cretaceous of 
> Sinnuiju City, North Korea)
> Changchengornis (Early Cretaceous of Chaomidianzi, China) Confuciusornis 
> (Early Cretaceous) Jinzhouornis

_Jinzhouornis_ is a Liaoning taxon, from the lower Yixian Formation.  The 
genus needs a more in-depth description.  Ditto for _Proornis_ from the 
Sinuiju Series of Kim Jong-Il's utopian socialist paradise.  The Sinuiju 
Series may belong to the Jehol Group.  _Changchengornis_ is certainly a 
confuciusornithid.

Cheers

Tim