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Re: Cionodon kysylkumensis vs Bactrosaurus kysylkumensis

In a message dated 6/9/00 4:32:02 PM EST, thescelosaurus@juno.com writes:


<< It sounds almost as if Nessov named the new material *Bactrosaurus
 kysylkumensis* and then referred the material named "Cionodon"
 *kysylkumensis* to it.  The two names appear to have different type
 material (a single dorsal vertebra is described as the lectotype of *B.
 kysylkumensis*, while Glut indicates a dentary is part of the holotype of
 "C." *kysylkumensis*).  Either that, or the lectotype of *B.
 kysylkumensis* came from the holotype of "C." *kysylkumensis*. >>

OK, here is the history of Cionodon kysylkumense Riabinin, 1931 as I have 
reconstructed it thus far. I have a photocopy of the original paper but it is 
presently inaccessible, buried in boxes after I moved back from Buffalo, NY 
in late 1996, so I can't check it directly. I read it long ago but can't 
remember a heck of a lot from it.

First of all, Cionodon kysylkumense is an incorrect original spelling, since 
Cionodon is a masculine noun and kysylkumense is an adjective with a neuter 
ending; the spelling was emended to Cionodon kysylkumensis by Weishampel & 
Horner in 1990, in the Hadrosauridae chapter of The Dinosauria.

Riabinin's original material was described as a fragmentary left dentary, 
four vertebrae, and a tibia from Djira-Kuduk, and two caudal vertebrae from 
Khodja-Kul (Lake Khodja) on the Amu-Daria River in the Kyzyl Kum Desert. 
Riabinin's original referral was tentative; I think he used a question mark: 
Cionodon? kysylkumense. This description is repeated in Steel, 1969 for 
Thespesius kysylkumense, which seems to be the earliest published reference 
of the species to the genus Thespesius. (It certainly predates the referral 
in Rozhdestvensky, 1977.) Glut's encyclopedia repeats this description nearly 
verbatim. I would have to check this, but the Thespesius referral >may< have 
appeared earlier in Rozhdestvensky & Tatarinov, 1964, the big Russian 
treatise on fossil reptiles. I have a photocopy of this but again, it's 
buried. If someone can check this, I'd like to hear about it.

Although Glut lists the dentary as holotype, I don't think Riabinin nominated 
any of the specimens as a holotype for the species. So without a holotype, 
Riabinin's specimens form a syntype series for the species. It was not until 
Nessov's redescription in 1995 that one of the vertebrae (TsNIGR museum 
#1/3760) was singled out as a lectotype and became the official type specimen 
of the species; all the other syntypes are now referred specimens. Nessov 
redescribed the material, in particular noting that the left dentary is 
actually a right maxilla (which you can see from the picture in Glut's 
encyclopedia, by the way: no hadrosaur dentary ever really looked like that), 
and adding a tooth to the list of specimens. The vertebrae, according to 
Nessov, are distinctive with a prominent ventral ridge, which is why, I 
suppose, he nominated a vertebra as the lectotype. Nessov also notes and 
describes a tooth for this species that wasn't listed previously but no other 
specimens are referred to it. Nessov referred the species to the genus 
Bactrosaurus in the 1995 paper, correctly spelling the species name 
Bactrosaurus kysylkumensis.

Somewhere along the line this species was also referred to the genus 
Trachodon. This may have ignorantly been done by me in 1978 in the first 
Mesozoic Meanderings, following a synonymy of Thespesius with Trachodon that 
was being bandied about at the time. My copy of MM #1 is buried, like 
Riabinin's original paper, so I can't verify this right now; it has been 22 
years since I published it.

In 1989, Nessov referred skull material to this species, and referred the 
species itself to Brett-Surman's genus Gilmoreosaurus as Gilmoreosaurus 
kysylkumense. This skull material was used to establish the new species 
Gilmoreosaurus arkhangelskyi by Nessov in that 1995 paper, and it is no 
longer considered part of Cionodon (or Gilmoreosaurus) kysylkumensis.

In Mesozoic Meanderings #3 first printing, I took the opportunity to correct 
the spellings of all the different names under which this species has been 
known that hadn't already been corrected. The species epithet spelling 
kysylkumense is not appropriate with any of the generic names to which the 
species has been referred: Cionodon, Trachodon, Thespesius, Gilmoreosaurus, 
or Bactrosaurus, which are all masculine nouns.

In all my lists I have noted no published instance of a spelling kyzylkumense 
or kyzylkumensis for the species epithet; it's always spelled with an s, not 
a z. Also, watch out for variant spellings of locality names from eastern 
Asia. In this case, they're in some Uzbek language and have no standard 
transliteration into English (Djira = Dhzira = Dzhirah, etc.; Khuduk = Kuduk, 
etc.). Best to sound them out and then see how close they seem to one another.

Here is the listing for Bactrosaurus kysylkumensis as it will appear in the 
second printing of MM #3:

Bactrosaurus kysylkumensis (Riabinin, 1931) Nessov, 1995 [nomen dubium]
        = Cionodon kysylkumensis Riabinin, 1931 emend. Weishampel & Horner,
            1990 [nomen dubium]
        = Cionodon kysylkumense Riabinin, 1931 [nomen dubium]§
        = Gilmoreosaurus kysylkumensis (Riabinin, 1931) emend. Olshevsky, 2000
            [nomen dubium]
        = Gilmoreosaurus kysylkumense (Riabinin, 1931) Nessov, 1989 [nomen
        = Thespesius kysylkumensis (Riabinin, 1931) emend. Olshevsky, 2000
            [nomen dubium]
        = Thespesius kysylkumense (Riabinin, 1931) Steel, 1969 [nomen dubium]§
        = Trachodon kysylkumensis (Riabinin, 1931) emend. Olshevsky, 2000
            [nomen dubium]
        = Trachodon kysylkumense (Riabinin, 1931) [nomen dubium]§

The § denotes an incorrect original spelling that is corrected in the 
preceding line.