[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Chaoyangia redescribed with new phylogeny of Mesozoic birds

Mickey Mortimer <mickey_mortimer111@msn.com> wrote:

> Well, hesperornithines do preserve some forelimb elements (humeri in 
> Hesperornis and Parahesperornis; humerus, radius and ulna in Baptornis; 
> humerus, radius, ulna and
> carpometacarpus in Pasquiaornis; humeri in Enaliornis).

The forelimb/wing bones (including carpometacarpus) of
_Parasquiaornis_ are mostly based on the abundant but undescribed
Bainbridge River material.  I know you know this... :-)   But neither
this undescribed material, nor any _Pasquiaornis_ material_, was
included in the _Chaoyangia_ phylogenetic analysis.  The fact that a
carpometacarpus is known at all for _Pasquiaornis_ is significant in
itself.  It's been thought that _Baptornis adventus_ retained carpal
bones, based on the shape of the distal articulations of the radius
and ulna.

Still, the wings of known hesperornitheans were *very* small.  Hence,
it's surprising that a putative volant bird like _Limenavis_ would
cluster with hesperornitheans.

> The Chaoyangia paper is excellent, btw.  It's surprising just how poorly 
> preserved Songlingornis is.  I hope she plans to tackle Hou's other birds 
> (Cuspirostrisornis, Longchengornis,
> Largirostrornis, Cathayornis? caudatus) soon.

I'll second that.  The paper also makes the interesting point that
Jehol enantiornitheans show arboreal adaptations, whereas
ornithuromorphs were better adapted for the ground.  Many of the
latter appear to have been ground foragers, or lived in or around
water.  I know this Enantiornithes-Ornithuromorpha ecological
dichotomy is not as simple as that.  Nevertheless, it may help explain
why the Ornithuromorpha produced multiple secondarily-flightless
lineages in the Cretaceous, but (so far) no secondarily flightless
enantiornitheans have been found.  Unless you include _Elsornis_,
which does at least appear to have been a ground forager (based on
pedal unguals); but it might have been a weak flier, rather than
completely flightless (http://dml.cmnh.org/2011May/msg00237.html)