Re: Viva Neornithine Birds!

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

> "If accurate, despite the vulnerability of such data to suboptimal 
> rooting, this record undermines early anticipations of K-T boundary 
> effects in modern orders and an evolutionary timespan in which major 
> divergences of neornithine lineages would extend through the early and 
> middle Cenozoic."

Here's the whole paragraph for context (refs removed):

"Quantitative estimation of rates of evolutionary change [...] -- given 
robust phylogenies [...] and adequate fossil records [...] -- have fostered 
more detailed hypotheses of phylogenetic bottlenecks and 'explosive' 
radiation near the K-T boundary [...]. However, there is growing evidence, 
at least based on Bayesian analyses of data largely or entirely from the 
mitochondrial genome, that most or all neornithine orders date from the late 
[sic!] Cretaceous [...]. If accurate, despite the vulnerability of such data 
to suboptimal rooting, this record undermines early anticipations of K-T 
boundary effects in modern orders and an evolutionary timespan in which 
major divergences of neornithine lineages would extend through the early and 
middle Cenozoic. Expectations for avian fossils of such antiquity are 
correspondingly conservative, and although fossils of such age potentially 
offer new calibration points for early avian lineages, there is diminished 
hope for points of calibration bearing on the relative antiquity of modern 
(super)orders of birds or precise molecular estimates of associated 
evolutionary rates characteristic of phylogenetic lineages."


As you can see, "this record" is not the fossil record, and Livezey and Zusi 
don't talk about their own data here, but about the molecular data of others 
and their interpretation by others: said data point to an old age for 
Neornithes and many clades therein, they say, but calibration of just those 
molecular analyses remains a problem because fossils of that age, they say, 
are unlikely to be discovered. Did you overlook 2 out of 3 sentences due to 
the length of the paper, or due to wishful thinking, or should I accuse you 
of quote-mining?

> Well, I hope not, because this would mean neornithines were special.

If one breeding pair -- or even just a female capable of parthenogenesis, in 
the case of Neornithes at least -- survives a mass extinction, all clades it 
belongs to have survived. This is different from the hypothesis that the 
mass extinction didn't affect those clades at all, and yet again different 
from the hypothesis that the mass extinction consisted of said clades 
outcompeting others. Remember: you need to find all possibilities because 
you can't test hypotheses that you've never thought of.