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RE: The Croc That Wanted to Be a Dinosaur


_Poposaurus gracilis_ is not a poposaurid?
What species does belong to _Poposaurus_?

--Mikko Haaramo

Mikko K. Haaramo, M.Sc.

Paleontologist IT Manager

Department of Geology
P.O.Box 64 (Gustaf Hällströminkatu 2)
FIN-00014  University of Helsinki

email: mailto:mikko.haaramo@helsinki.fi
www: Mikko's Phylogeny Archive [http://www.fmnh.helsinki.fi/users/haaramo/]


> -----Original Message-----
> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu] 
> On Behalf Of Jaime A. Headden
> Sent: 29. tammikuuta 2006 6:27
> To: dinosaur@usc.edu
> Subject: RE: The Croc That Wanted to Be a Dinosaur
>   There are several "family-level" names available for this group of
> crurotarsans:
> Poposauridae Nopcsa, 1928
> Ctenosauridae Kühn, 1961
> Ctenosauriscidae Kühn, 1964 (revised)
> Lotosauridae Zhang, 1975
> Shuvosauridae Chatterjee, 1993
> Chatterjeeidae Long and Murray, 1995
>   Taxa included (potentially, following Nesbitt, 2003, 2005 
> and Nesbitt and Norell, 2006):
>   *Hypselorhachis mirabilis*, *Lotosaurus adentus*, 
> *Cteosauriscus koeningi*, *Chatterjeea elegans*, *Shuvosaurus 
> inexpectatus*, [new taxon, Nesbitt and Norell, 2006], 
> *Sillosuchus longicervix*, *Poposaurus gracilis* (incl.
> *Lythrosuchus langstoni*?), *Bromsgroveia walkeri*, 
> *Arizonasaurus babbitti*
>   These animals appear to form a clade apart from rauisuchids 
> or poposaurids proper (*Rauisuchus*, *Teratosaurus* sensu 
> Dzik, *Poposaurus*, *Postosuchus*, *Saurosuchus*, 
> *Tikisuchus*, etc.), and in which perhaps the tall dorsal 
> spines are prevalent before the presence of beaks becomes 
> more extensive in the only [three] taxa to bear them, one 
> which has a sail and one which does not, the other being 
> unknown in this condition and perhaps synonymous with the latter.
> *Lotosaurus* also has the shortest sail of the 
> "ctenosauriscids" and so it might be worth considering that 
> the sail was being minimized, perhaps moving the animal into 
> an environment or population structure that did not require it.
> If we choose to use a single name for these animals, 
> Poposauridae Nopcsa has priority. If we choose to name each 
> small grouping of taxa with an -idae clade, we might still 
> require a more inclusive name to set these apart from the 
> "rauisuchids" or "teratosaurids" or "prestosuchids" that form 
> this complex or grade of basal suchians. It might be easiest 
> to use the given nomenclature and modify from it, reducing 
> the need for excessive -idae clades. One could use 
> "Paniphora" for the clade including the first fin-back, and 
> "Odontorhynches"
> for those toothless clades, included by "Paniphora", and 
> avoid the whole Linnaean quagmire of -idaes and -inaes and 
> names "changing ranks".
>   There is an odd biogeographical conundrum to draw from this 
> arrangement,
> however: 
>   *Hypselorhachis* and *Ctenosauriscus* are both from 
> southern Africa, and their jaw anatomy is unknown, though 
> perhaps some of those southern African crania may belong to 
> something like them rather than classically rauisuchid like 
> *Postosuchus* (that means you, *Alwalkeria*). *Lotosaurus* is 
> from China.
> *Sillosuchus* is from South America. *Bromsgroveia* is from 
> England. And all the rest are from North America (actually, 
> to be precise, to the American Southest). While the Late 
> Triassic continents were largely in connection to one 
> another, many of these taxa appear to form a general gradient 
> with regarded to cranial, and sail, anatomy, with Nesbitt and 
> Norell finding a grouping of tall-spined taxa, and within 
> that a grouping of *Arizonasaurus* and *Ctenosauriscus*; 
> *Bromsgroveia* may also belong to this group. *Lotosaurus* is 
> allied, but as shown with the crania, clearly represents an 
> edentulous lineage with *Shuvosaurus* and the new taxon. If 
> we assume such consistency, these taxa have essentially been 
> "bouncing" around the globe, and the North American taxa may 
> not form a single, exclusive clade of their own. Most curious.
>   I should note that my use of "croc" and "crocodiles" and 
> "crocodylians" in my last post on this topic were drawn from 
> an inflated sense of the use of "croc"
> for the Crurotarsi/Crocodylotarsi/Crocodylomorpha clades, and 
> not from any special reference to the Crocodylia itself.
>   In addition, I have received some comments on my regarding 
> of the lack of availability of Nesbitt and Norell's name 
> given the online publication. I have not, unlike for Pal. 
> Elec. or Naturwiss., seen a statement regarding availability 
> of online taxonomy. Jerry Harris has an application in 
> _Bulletin of Zoological Nomenclature_ regarding the issue of 
> digital nomenclature and its priority over press 
> publications. The ICZN has made clear it's consideration of 
> digital nomenclature, but not whether digital names have 
> priority over later published _paper_ names, even if its the 
> same name, making the date of those names questionable. The 
> name *Dakosaurus andinensis* was digitally published only 
> months before the publication finalized it, but which date is 
> more valid?
> The issue is not clear, and thus the question should be 
> validated before assuming, simply because the paper is 
> online, that the taxonomy is valid. As it is, I will accept 
> the press date when the paper is published as the valid issue 
> of the name's availability, but not before, until the 
> publisher says otherwise.
>   Cheers,
> Jaime A. Headden
> "Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
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