Re: SV: 55 million year old parrot found

[evelyn sobielski <koreke77@yahoo.de>]

> Folks, when is the oldest known psittacine, apart from this
> find?    I 
> honestly thought I'd previously been told that the
> oldest known psittacine 
> was in Cretaceous or end-Cretaceous times.
> 
> I've plowed through these posts.   People have
> consistently named finds from 
> a good deal later than the find in question, but tehy also
> insist that their 
> are finds that old, and insist that hte controversial point
> is that this 
> particular find is different from other psittacines.
> 
> If the only point of controversy is that this find is
> different from other 
> psittacines, why has noone mentioned other psittacine finds
> this old?

The oldest psittacines til now were the Riversleigh cockatoo, the Langerbaanweg 
_Agapornis_ and perhaps the uncertainly-dated _Conuropsis fratercula_, all 
dating to about 25-20 million years ago. But you probably mean the "psittacid". 
That would probably be _Archaeopsittacus_, which is maybe 27 million years old 
(discovered back in the 19th century, it cannot be dated very accurately now).

There are, however, many psittaciforms about as old as _Mopsitta_, but these 
are pseudasturids and _Quercypsitta_, not psittacids. In vernacular terms, they 
ought to be called "parrot relatives", not "parrots", as they lacked most of 
the features (like the hooked bill) that characterize the latter.

In addition, there are some scraps contemporary with _Mopsitta_ and the 
pseudasturids (such as _Puchrapollia_ or parts of the _"Precursor"_ material or 
_"Primobucco" olsoni_ which actually seems to be the same as _Pulchrapollia_) 
that are sometimes assigned to the psittacids, but at lerast until now this 
seemed over-entusiastic (the prevailing trend until awareness of phylogeny 
settled in was to assign fossil birds from as far back as the Cretaceous to 
living clades like albatrosses or cormorants). It may be however that we have 
stem-group representatives of psittacids here. 

But then the question of the geographic pattern is to be explained, given that 
the group existed in the later Oligocene at least, and that it occurs in the 
fossil record about at the same time in Australia and France, with a modern 
representative in the former and a less modern representative in the latter, 
and that the most ancient living psittacine lineages are from the Australia-New 
Guinea-New Zealand region. Given the general "modernness" of the Early Miocene 
fossils, it would seem that actual parrots originated more than 30 million 
years ago, but not in Europe. _Archaeopsittacus_ would then be a member of a 
lineage more basal than most parrots, that was the first one to colonize 
Eurasia, perhaps 30 million years ago (depending on whether the psittacid 
lineage split off in the Early Oligocene or earlier). 

If _Mopistta_ is as modern as it could be, this scenario obviously is wrong. 
But on the other hand, _Mopsitta_ might represent an early psittaciform close 
to but not actually part of the lineage that moved east and eventually became 
the ancestors of the modern parrots, then the scenario still holds. 

But at present, all we can say is that modern parrots, parakeets and cockatoos 
existed in the Early Miocene, and that by then they were already diverse enough 
to place their origin considerably earlier, and that at least the living 
lineages originated in the SW Pacific region.

The Cretaceous fossil is UCMP 143274 from the Lance Formation. It probably is 
of a caenagnathid, those "bird-beaked" oviraptorosaurians. Photos are here: 
http://www.nature.com/nature/journal/v396/n6706/images/396029aa.eps.2.gif

For the most recent comprehensive review of the fossil psittaciform material 
known til then, see Waterhouse's review "Parrots in a nutshell" 
(doi:10.1080/08912960600641224)


Regards,

Eike


      __________________________________________________________
Gesendet von Yahoo! Mail.
Dem pfiffigeren Posteingang.
http://de.overview.mail.yahoo.com