Re: on-line fossil birds list

[David Marjanovic <david.marjanovic@gmx.at>]

> This seems to be wrong.  Read Gao and Ren (2006).  It argues
> VERY convincingly for a Middle Jurassic age.

Interesting. Please send me the pdf.

I have only read a reply by He et al. (2005) to a critique of their 2004 
paper. They defend their conclusion there (but don't mention the Tuchengzi 
Fm anymore) and show evidence for contamination by older crystals.

Personally, I get the impression that the lateral correlation between almost 
any two sites is deeply mysterious at the moment. No wonder -- the area is 
vast and consists entirely of 1000 m high mountains.

> "[...] He et
> al. (2004) also claim that, contrary to Ren et al. (2002) and
> Liu and Jin (2002), ¡°at the Daohugou locality, the fossilbearing
> sediments are also found to overlie the Tuchengzi
> Formation at a few sites¡±, but they have not cited the
> coordinates of the sites where this occurs nor have they
> documented this contact in a photograph of these sites."

Well, OK, but that doesn't mean the site doesn't exist...

He H[uai]y[u], Wang X., Zhou Z., Zhu R., Jin F., Wang F., Ding X. & A. Boven 
(2005): Reply to comment by Liu and Liu on "^40Ar/^39Ar dating of ignimbrite 
from Inner Mongolia, northeastern China, indicates a post-Middle Jurassic 
age for the overlying Daohugou Bed", Geophysical Research Letters 32, 
L12315, 3 pages

There's also a paper by these authors from 2006 on the age of the Dabeigou 
Fm (Hauterivian-Barremian boundary), but there they don't mention the 
Daohugou Bed much, IIRC. (The pdf of that one is on the laptop, so I can't 
check right now.)