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

Re: Details on Caudipteryx



 
Diagnosis- [...] only two phalanges present on manual digit III; [...]
There are only two phalanges in manual digit III.  They are both very small, the second smallest, and do not reach past the midpoint of phalanx II-1.  There is no ungual.
:-o :-o :-o What? Why? How? ??? Bizarre convergence to Ornithothoraces...
Holotype- (NGMC 97-4-A) (890 mm) skull (76 mm), lower jaws, cervical vertebae, cervical ribs, dorsal vertebrae, dorsal ribs, gastralia, twenty-two caudal vertebrae, chevrons, coracoid, sternal plate (36 mm), humeri (69 mm), radii, ulnae, mani,
Unfortunately "manus" again, allegedly with a longer u... manus belongs to the u declination, which has plural on -us, whereas most other words (humerus, radius, astragalus, tarsus...) on -us belong to the o declination, which has -i.
Teeth are serrationless and constricted at the base.
=8-)
    Ruben and Jones (2000) support the hypothesis Caudipteryx is a secondarily flightless bird.  They argue against the theropod status of Caudipteryx by refuting the three "unambiguous characters" cited by Ji et al. (1998) that birds have and it lacks.  They say the quadratojugal cannot be proven to have been sutured with the quadrate, as they do not contact in the holotype and show a photo of the specimen which differs in this aspect from the figure in Ji et al..  Oviraptorid specimens GIN B and ZPAL MgD-I/96 (Maryanska and Osmolska, 1997) show a cotylar articulation between the two bones and Velociraptor has a reduced loose contact (Barsbold and Osmolska, 1999), so the character wouldn't mean much even if they are correct (the cranial elements of Caudipteryx are loosely articulated and sutures between most cannot be seen).
A cotylar articulation without cranial kinesis?
- reduced hypopubic cup.  Plesiomorphic and present in nearly all dinosaurs anyway....
What exactly is a hypopubic cup?
ball-shaped femoral head.  Plesiomorphy only absent in Archaeopteryx and Rahonavis.
- greatly shortened tail with evidence of pygostyle formation.  See above.
So they have got this idea, too?
In conclusion, "shortened tail" is the only character presented by critics that is a potential Caudipteryx-pygostylian synapomorphy.  Several new discoveries surprisingly add evidence to this hypothesis,
=8-)
including the possible low dorsal vertebral count
which is odd, considering the 5 sacral vertebrae (don't other oviraptorosaurs have 7 and birds 8 or more?)
 
Is it possible that all known specimens (that stretches it, of course) are immature, which could explain the unfused sterna (sutured in Velociraptor, fused AFAIK in other oviraptorosaurs, Pelicanimimus, tyrannosaurids, Sinraptor...) and the 5 sacrals?
* Adding four characters
mmmm... which ones?
Bambiraptor, Sinornithosaurus, Microraptor, Unenlagia, Rahonavis and Archaeopteryx are successive outgroups to Yandangornis and pygostylians (sorry, no more secondarily flightless dromaeosaurs).
:.-( ;-)
 
Great work, anyway!!!