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Re: New basal dinosauriform
David Marjanovic <email@example.com> wrote:
> Oh yes, and it makes me happy that it's finally out after about 60 years.
To put this in a historical context, when _Nyasasaurus_ was first
described (but not formally named), there was not yet a Tanzania. It
was still the British territory of Tanganyika.
> :-) And the beastie has an interesting phylogenetic position (or two), too!
Indeed. It also emphasizes just how rare dinosaurs (and dinosaur-like
dinosauriforms) were in the Middle Triassic. Not as rare as Middle
Triassic pterosauromorphs though (zero discoveries so far).
_Thecodontosaurus alophos_ (named by Haughton, 1932) is referred by
Nesbitt et al. to their new taxon _Nyasasaurus parringtoni_. So
shouldn't the name be _Nyasasaurus alophos_...? (Unless _T. alophos_
is a nomen nudum.)
Also, _Nyasasaurus_ is diagnosed based on a unique combination of
characters, some of which may be plesiomorphic for clades "just
outside or within Dinosauria" (Nesbitt et al., 2012). This is fine by
me, because a genus can be diagnosed in the absence of autapomorphies;
so _Nyasasaurus_ is a valid genus in my book. However, _Lagosuchus
talamapeyensis_ was regarded as a nomen dubium for much the same
reason (Sereno & Arcucci, 1994): the holotype of _Lagosuchus_ has no
autapomorphies, and its combination of characters (which can
distinguish it from other basal dinosauriforms, like _Marasuchus_) are
plesiomorphic for various ornithodiran clades. So if _Nyasasaurus_ is
a valid genus (and I have no doubt that it is), then so is
_Lagosuchus_ (contra Sereno & Arcucci, 1994).