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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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