AW: SV: 55 million year old parrot found

[evelyn sobielski <koreke77@yahoo.de>]

--- Tommy Tyrberg <tommy.tyrberg@norrkoping.mail.telia.com> schrieb am Sa, 
17.5.2008:

> Von: Tommy Tyrberg <tommy.tyrberg@norrkoping.mail.telia.com>
> Betreff: SV: 55 million year old parrot found
> An: koreke77@yahoo.de, dinosaur@usc.edu
> Datum: Samstag, 17. Mai 2008, 21:19
> Interesting but not sensational. The Mo Clay fauna is
> tropical, with trogons, louries and mousebirds, so parrots
> is not unexpected. As a matter of fact Kristoffersen
> mentions the presence of Psittaciforms in her dissertation
> (2002), but unfortunately this was never published
> properly.

The sensational bit is not the presence of Psittaciformes - that I wouldn't 
even consider really interesting if they were (as the second fossil described 
in the paper) pseudasturids. But _Mospitta_ is not pseudasturid. Also, it does 
not resemble _Psittacopes_.

So the "somewhat interesting" bit is that the origin of Psittaciformes was 
apparently in Eurasia, say about 60 mya or so. That much was already suspected. 
The "sensational" bit is that _Mopsitta_ is so different, at least in the 
preliminary inspection, from other stem psittaciforms. 

To find a psittaciform there and then is nice, but absolutely not suspected. To 
find *such* a psittaciform there and then is stunning:

"Although it is not absolutely certain on the basis of preserved features 
(humeral morphology cannot be entirely diagnostic at this level), it is highly 
likely that Mopsitta tanta is a member of Psittacidae, therefore providing 
further support to the hypothesis of an early Eocene (or earlier) radiation of 
Psittaciformes; it is likely that representatives of crown-group Psittaciformes 
such as Mopsitta, existed in the Early Eocene alongside their stem-group 
counterparts Pseudasturidae and Quercypsittacidae."

I would be a bit reserved about "highly likely", but that there are grounds to 
make such a suggestion at all is interesting. The date is not problematic. But 
there is still this 30-million-year gap between _Mopsitta_ and 
_Palaeopsittacus_, and the fact that the earliest *crown* lineages of 
Psittaciformes to diverge are from Sahul and NZ. And their radiation could be 
tentatively dated to the late Eocene/early Oligocene, given that a cockatoo 
bone indistinguishable from modern _Cacatua_ was found at Riversleigh, and that 
a) the Cacatuinae are an ancient but probably not *the* most ancient extant 
psittaciform lineage, while b) _Cacatua_ is very advanced among the cockatoos 
(meaning that the black cockatoo and palm cockatoo lineages for example must 
also have been distinct by the time the Riversleigh cockatoo lived).

(There is a mol-phyl paper that proposes a Mesozoic origin of Psittacidae, but 
they use a bad clock. And citing the "mandible" form North America in their 
support is not encouraging either)

In short, the closer _Mopsitta_ is to crown psittaciforms phylogenetically, the 
larger the question mark at their base becomes.


Regards,

Eike

PS: Mayr has published a new study about crown psittaciforms in Emu. Basically: 
the lorikeets and most of the Old World tiny parrots apparently form a clade; 
support is fairly robust (given that too little cladistic studies with 
comprehensive sampling exist for reasons unknown) by mol and morph characters, 
and he discusses a characteristic osteological apomorphy. But apart form the 
latter it's more of a fairly brief review.


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