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RE: Cathayornis paper in Geological Bulletin of China

It should be noted that not only is Cathayornis a junior synonym of Sinornis 
(Sereno et al., 2002- ignored by all Chinese works so far), but the evidence 
for referring chabuensis to that genus is problematic.  Of the characters 
listed by Li et al. (2008) in its original description, the longitudinal radius 
groove is present in all enantiornithines more derived than Longipteryx. 
Sinornis actually has a broad intermetacarpal space (contra Li et al.), with 
the illusion of a nearly absent space in some enantiornithines due to 
postmortem distortion of the flattened third metacarpal. Several other 
enantiornithines have only one phalanx on manual digit III (Alethoalaornis, 
Concornis, Eoalulavis, Eoenantiornis, Gobipteryx, Hebeiornis), which is similar 
to Sinornis' in being closely appressed to phalanx II-1 when articulated (e.g. 
Eoalulavis, Hebeiornis) and is actually fused in Alethoalaornis based on its 
figure. Finally, Li et al. state "proportions of limb bones" are similar 
between Sinornis and chabuensis. The ulnohumeral ratios are indeed quite 
similar (98% vs. 97%), but so are those of "Cathayornis" caudatus (100%), 
Rapaxavis (100%) and Longirostravis (98%). The humerofemoral ratio of 
chabuensis (113%) is similar to Sinornis (114-117%), but so are "Cathayornis" 
caudatus (113%) and Eoenantiornis  (111%). The tibiofemoral ratio of 127% is 
again close to Sinornis' (124-126%), but so are Dapingfangornis (126%), 
Jibeinia (126%), Shanweiniao (128%) and Longirostravis (129%). The 
tarsometatarsofemoral ratio of 63% is actually very low compared to Sinornis 
(70%), with many enantiornithines having ratios closer to Sinornis (67-73% in 
Alethoalaornis, Dapingfangornis, Hebeiornis, Jibeinia, Largirostrornis, 
Liaoxiornis, Shanweiniao, Longirostravis, 
  Longipteryx, Iberomesornis and Cuspirostrisornis). Thus there are no unique 
shared characters with Sinornis and while the limb proportions are mostly 
similar, they are not necessarily derived. It is here excluded from Sinornis, 
though further study will be needed to determine which taxa it is most closely 
related to.

Mickey Mortimer

> Date: Sun, 19 Sep 2010 11:57:48 +0000
> From: bh480@scn.org
> To: dinosaur@usc.edu
> Subject: Cathayornis paper in Geological Bulletin of China
> From: Ben Creisler
> bh480@scn.org
> Just came across this ref (sorry--don't have pdf). In
> case it has not been mentioned here:
> ZHANG Yu-guang, ZHANG Li-fu, LI Jian-jun, LI Zhi-heng,
> 2010. New discovery and flying skills of Cathayornis from
> the Lower Cretaceous strata of the Otog Qi in Inner
> Mongolia, China. Geological Bulletin of China. 2010 7:
> 988-992.
> This paper describes a new fossil named Cathayornis
> chabuensis discovered in 2008,from Chabu,Otog Qi in Inner
> Mongolia, which also represents the second Cathayornis
> found in this area. The specimen preserves a complete
> sternum and furcula with some other clear skeleton
> impressions. A comparison of the new material with
> Eocathayornis walkeri, C.yandica and C.chabuensis shows
> that except the similarity between C. yandica and C.
> chabuensis,the later one displays some more advanced
> characteristics than E.walkeri and C. yandica.
> Besides,the functional morphological analysis related to
> flying skills supports that C. chabuensis is not only
> capable of flapping flight as C.yandica in the Early
> Cretaceous,but also possesses an advanced flying system
> indicating a stronger flying capability.
> http://apj1.cnki.net/kcms/detail/detail.aspx?
> QueryID=25&CurRec=3&dbCode=CJFD&filename=ZQYD201007005&dbn
> T0=