Re: [dinosaur] Psittacosaurus amitabha, new species from Cretaceous Ondai Sayr Locality, Mongolia

[Tim Williams <tijawi@gmail.com>]

A specimen-level phylogenetic analysis of _Psittacosaurus_ could also
be helpful.  It'd be a huge amount of work, but would shed light on
whether or not there are well-supported clades within _Psittacosaurus_
(as currently defined) that could provide the foundation for new
genera.

However, despite being a highly speciose genus, there is no evidence
that _Psittacosaurus_ is anything other than monophyletic.  IIRC, no
phylogenetic analysis has ever found the genus _Psittacosaurus_
(including _Hongshanosaurus_) to be paraphyletic relative to
neoceratopsians.  So although highly speciose, _Psittacosaurus_ is not
problematic.

The issue with _Iguanodon_ was that the genus was founded on a
questionable type, as well as being para- or polyphyletic (at least
for some species that had been assigned to _Iguanodon_).

There are speciose dinosaur genera in far greater need of an overhaul
than _Psittacosaurus_.  _Mamenchisaurus_ and _Omeisaurus_ come to mind
- some species may actually belong in other mamenchisaurid genera
(like _Anhuilong_ or _Yuanmousaurus_), or deserve their own genera
(like a revived _Zigongosaurus_).

On Sat, Jul 27, 2019 at 6:43 AM Paul P <turtlecroc@yahoo.com> wrote:
>
> Genus vs. species is sometimes arbitrary, but not always. Clustering 
> algorithms can help to determine which it should (probably) be. 
> Morphometrics, cladistics, etc.
>
>
> On Friday, July 26, 2019, 2:03:40 PM UTC, David Marjanovic 
> <david.marjanovic@gmx.at> wrote:
>
> > [...] Psittacosaurus amitabha is resolved as the most basal member of the 
> > genus Psittacosaurus in our phylogenetic analysis. This taxon expands our 
> > knowledge of the already-speciose genus Psittacosaurus
>
> These two sentences are arbitrary; nothing prevented the authors from naming 
> a new genus for this species. But apparently psittacosaurid genera are like 
> Highlanders, there can be only one...