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Re: Viva Neornithine Birds!
"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
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
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.