Re: Regarding Mochlodon suessi

[David Marjanovic <david.marjanovic@gmx.at>]

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.