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Re: Regarding Mochlodon suessi

I repeat the entire message in Real True Plain Text just in case it didn't get through to everyone. My reply is included.

----- Original Message -----
From: "Sven Sachs" <sachsdml@yahoo.de>
To: <dinosaur@usc.edu>
Sent: Saturday, June 24, 2006 10:01 AM
Subject: Regarding Mochlodon suessi

We just noticed that our paper "Juvenile ornithopod (Dinosauria: Rhabdodontidae) remains from the Upper Cretaceous (Lower Campanian, Gosau Group) of Muthmannsdorf (Lower Austria)" is subject of a vivid discussion in the DML and want to clarify some essential points.
At first, the species name "suessi" was first coined by E. Bunzel (1871) as Iguanodon Suessii to include ONLY the dentary and two small vertebral centra. All other specimens, later identified as to belong to an ornithopod were either referred by Bunzel to other taxa (e.g. "crocodili ambigui" and Lacerta sp.) or have not further been mentioned.
Although Bunzel did not formally specify a holotype, he clearly indicated and figured, what of the material available to him represents his newly erected taxon (ICZN 1999: Art. 73.1.2). This is a clear obligation for the subsequent decision on the lectotype.
The first reviser was H.G. Seeley (1881). He considered the dentary as the name-bearing material of Iguanodon Suessi and referred the parietal and scapula fragments "probably" to the same taxon. The rest of the ornithopod material was dispersed by him across three new taxa, Rhadinosaurus alcimus, Ornithomerus gracilis and Oligosaurus adelus. The latter was named by him without own figures, referring only to Bunzel's work. The hypodigm of O. adelus includes heterogenous specimens including probably a crocodilian metapodial and indeterminate fragments. Additionally he listed the two vertebrae included by Bunzel in Iguanodon Suessii under O. adelus solely for the reason, that he has no better place to put them.
In conclusion the only name-bearing type material of Iguanodon Suessii (and Mochlodon) ARE the dentary and the vertebrae, figured by Bunzel (1871) (cf. ICZN 1999: Art. 71-74, esp. 73.1, 74.1).
We agree with some comments in the mailing list that IF specifically diagnostic characters can be identified from the LECTOTYPE (dentary) of Iguanodon Suessii, then Mochlodon suessi has to be considered valid and Mochlodon is a valid senior synonym of Zalmoxes. Given further advancements of knowledge on rhabdodontid morphology this may be the case in the future. However, at the present state isolated rhabdodontid dentaries are not considered diagnostic at genus level (cf. Weishampel et al. 2003). The vertebrae (currently lost) are not diagnostic beyond Ornithopoda indet at best.
Therefore we consider this taxon as a nomen dubium and Mochlodon no longer available as a senior synonym of Zalmoxes. None of Seeley's new hypodigms show diagnostic characters and R. alcimus, O. gracilis and O. adelus are nomina dubia and/or composites respectively. Therefore they are not available as senior synonyms of Zalmoxes.
In a SECOND step we compared all the available ornithopod material from Muthmannsdorf, which was NOT included into the original hypodigm of Iguanodon Suessii by Bunzel (1871) We considered the hypothesis that it belongs to the same individual as the dentary and vertebrae to be the most parsimonious alternative, but of course it is not verifiable. Since these elements were not included into the name-bearing type by the original author (Bunzel) and the first reviser (Seeley) and instead partly form types of other taxa erected by Seeley, they are not available as part of the type series.
Again the "reunited" material is NOT determinable at species level but we found closer similarities to Zalmoxes than to Rhabdodon. However several differences or ambiguous characters suggest that it is NOT identical to one of the Romanian species. Therefore we referred it to Zalmoxes sp. (it may be arguable whether cf. Zalmoxes sp. may be more appropriate; however we found no characters that contradict the referral to Zalmoxes at genus level).
This in turn implies that even if one will consider the whole rhabdodontid material from Muthmannsdorf as the name-bearing type (an approach we consider incorrect because of (1) the regulations of ICZN Art. 73.1 and 74.1 and (2) the lack of UNAMBIGUOUS evidence that all of the material belongs to a single individual) it retains its status as nomen dubium.

So this "'reunited' material" does not include the lectotypes of Bunzel's and Seeley's taxa?

 Best wishes,

 Sven Sachs & Jahn J. Hornung

P.S.: It was mentioned that Z. shqiperorum is misspelled Z. shpiperorum in our paper. This was indeed the case in the first online version and happened without our knowledge. In the printed / currently online version, however, it is correctly written as Z. shqiperorum.