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Re: Titanis walleri age range



The original report on Titanis (Brodkorb, 1963, The
Auk, vol 80) states:

"Associated Fauna: Other birds collected at the type
locality by Waller and Robert Allen include a
Pleistocene grebe, _Podilymbus magnus_ Shufeldt, and
five living species, _Phalacrocorax auritus_ (Lesson),
_Aythya affinis_ (Eyton), _Mergus merganser_ Linnaeus,
_Buteo jamaicensis_ (Gmelin), and _Meleagris
gallopavo_ Linnaeus.  The preponderance of living
species suggests a late Pleistocene age.

...
     
     The possibility that the fauna is not coetaneous
seems slight.  The material is uniform in appearance,
being well mineralized and black or dark brown in
color."

>From your description below, it seems that McFadden
dated the fossils themselves by the new method.  Is
this so, and, if so, were different ages obtained for
the various members of the fauna?

The Santa Fe River Titanis remains are pretty sparse. 
One possibility is that the bird lived in a poor
fossilizing environment and that the bones were washed
down from that environment in the stream and
mineralized along with bones from local birds. 
Another is that fossils were eroded out of an older
bed by the stream and re-mineralized to resemble bones
that were in the process of fossilization.  A third is
that the mineralization of fossils in the older bed
left them visually indistinguishable from the
mineralization of bones in the stream.  

At this moment, the rare-earth uptake evidence has to
be considered, but I think the question of Titanis'
age range should remain very open pending further
discoveries.

Glen Ledingham 
  

--- Jeff Hecht <jeff@jeffhecht.com> wrote:

> At 3:44 PM -0700 10/28/06, Ian Paulsen wrote:
> >HI:
> > So is the specimen from Texas (Baskin 1995, JVP
> 15: 842-844. ) not T.
> >walleri or not from the late pleistocene?
> >
> According to my notes, dating based on the uptake of
> rare-earth elements (a new technique) was done on
> the Sante Fe River, Florida and Texas sites. In both
> cases, the Titanis fossils were mingled with fossils
> from both the Pliocene/early Pleistocene and the
> late Pleistocene. In Santa Fe, FL, the rare-earth
> element signatures matched those of 2 million year
> old mammal fossils. In Texas, the rare-earth
> signatures matched those of Pliocene horse fossils.
> That implies there is no evidence for late
> Pleistocene Titanis. 
> -- 
> Jeff Hecht, science & technology writer
> jeff@jeffhecht.com  http://www.jhecht.net
> 525 Auburn St., Auburndale, MA 02466 USA
> v. 617-965-3834; fax 617-332-4760
>