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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 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.