Re: Darwinopterus notes

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

>  Free Darwinopterus download:
http://rspb.royalsocietypublishing.org/content/early/2009/10/12/rspb.2009.1603.full.pdf

Thanks a lot!

The supp. inf. (a Word file) is accessible from here: 
http://rspb.royalsocietypublishing.org/content/early/2009/10/12/rspb.2009.1603/suppl/DC1

It starts as follows:

>>
A. Age of the Tiaojishan Formation

The strata in western Liaoning that yielded *Darwinopterus* gen. nov. 
are referred to as the Lanqi Formation (Bureau of Geology and Mineral 
Resources of Liaoning Province 1989), but appear to be equivalent to the 
Tiaojishan Formation of Hebei and Inner Mongolia. The Tiaojishan 
Formation was named prior to the Lanqi Formation, thus it has been 
suggested that the latter name be replaced by the former (Wang et al. 
2000), a proposal we accept here. The Tiaojishan Formation is generally 
regarded as Middle (Zhang & Zheng 1991; Liu et al. 2006; Cheng & Li 
2007) to Upper Jurassic (Chang et al. 2009) (Late Bathonian-Early 
Kimmeridgian) in age, although it may date to the early Middle Jurassic 
(Aalenian) in Jianchang County (Davis et al. 2001). The unit has been 
dated using radiometric techniques at 169-152 Mya by Liu et al. (2006) 
and 165-156 Mya by Zhang et al. (2008).
<<

Compare:
http://stratigraphy.science.purdue.edu/gssp/index.php?parentid=35
Kimmeridgian-Tithonian boundary 150.8 +- 4 Ma ago
Oxfordian-Kimmeridgian boundary 155.6 +- 4
Callovian-Oxfordian = MJ-LJ boundary 161.2 +- 4
Bathonian-Callovian boundary 164.7 +- 4
Bajocian-Bathonian boundary 167.7 +- 3.5
Aalenian-Bajocian boundary 171.6 +- 3

I'd say it was a bit irresponsible to put "from the Middle Jurassic of 
China" into the abstract and the introduction. It has about a 50 % 
chance of being true.

>  And I'm also disappointed to read this from the
>  Suppplmentary Data: "The search was terminated at 500,000 trees due
>  to memory limitations." That's a sign that something is wrong. The Lü
>  study needs to use more of the available taxa.

And a lot more characters! 117 characters for 56 taxa -- that's less 
than twice as many. Under three times I wouldn't bother publishing.

Also, all characters were unordered. Some of them are continuous, like 
number 6: "Rostral index: 1.5 or less (0); 1.5-3.0 (1); >3.0 (2)". This 
is not defensible (Wiens, 2001, Syst. Biol.) -- the assumption that 
underlies ordering, namely that it is easier to change from a character 
state to a similar one than to a more different one, was _already_ used 
to divide the continuous character into states; if it's easier to go 
from 1.3 to 1.4 than to 1.6, it must also be easier to go from 1.3 to 
2.0 than to 3.5, in other words, not ordering the character is logically 
inconsistent.

The consistency index is strangely _high_ (0.47).