Re: Ceratonykus oculatus

["Jaime A. Headden" <qilongia@yahoo.com>]

Tim Williams wrote:

<The last sentence can be taken with a grain of salt; but it would be 
interesting to know the rationale behind their claim.  It doesn't appear to be 
"alvarezsaurs-are-birds/birds-are-not-dinosaurs" boilerplate (the title implies 
that the authors believe them to be dinosaurs, at least).  Most of the paper is 
in Russian, although the classification is in English (family Parvicursoridae, 
subfamily Mononykinae).>

  The authors appear to refer to the brain as a nonavian design, with the 
cerebrum directly anterior rather than over the cerebellum, with the optic 
lobes positioned widely and lateral rather than slung into the midbrain with 
the medulla. The brain is elongated, narrow, and low. 

  The authors also clearly separate the North American/Asian lineage from the 
South American lineage (Alvarezsauridae proper), which would explain their use 
of the terminology. As such, even if Alvarezsauridae is confined to 
*Alvarezsaurus* and does not encompass all alvarezsaurs, *Parvicursoridae* 
Karhu and Rautian 1996 has priority over the coordinated-rank taxon 
*Mononychidae* Chiappe et a. 1998.

  Preserved material, MPD 100/120 (holotype):

  Skull and mandible complete from foramen magnum to just anterior to the 
lachrymals; a series of cervical vertebrae, and the first and several 
succeeding caudal vertebrae; an apparent sternal keel, coracoid (which 
preserves the same lateral ridge of *Patagonykus*), proximal 1/3 of humerus, 
carpus including two anomolous elements forming "spurs" (hence the name), and 
the first mdI phalanx (no ungual); anterior portion of the iliac blade, 
proximal femur, tibiae w/o fibulae, both sets of metatarsals excluding the 
first and fifth, and with questionable fusion of the tarso-metatarsal region, 
and proximal phalanges 1-2 of nearly all digits.

 The tibiotarsal length is 89 mm long, which is comparable to the tibiotarsus 
of *Parvicursor remotus* (PIN 4487/25) of 75.6mm, and *Mononykus olecranus* 
(GIN 107/6) of 175.2mm, and 185mm of an undescribed alvarezsaur from Alberta 
(Longrich and Currie, in press).

  Found at Hermiin Tsab (Khermeen Tsav) of the Nemegt Formation in Omnogovi 
Aimag of Mongolia.

  Cheers,

Jaime A. Headden

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)