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Re: Darwinopterus notes
Free Darwinopterus download:
Thanks a lot!
The supp. inf. (a Word file) is accessible from here:
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).
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
The consistency index is strangely _high_ (0.47).