Wednesday, December 9, 2015

"Indistinguishable from random"

Here is a study on how the published dinosaur cladograms compare to the stratigraphic (time) record. It is significant that there is a total lack of congruence, it is "indistinguishable from random", for Paraves.

Wills et al (2008): (Full article) (Table 1)
Evidence for the evolutionary history of most groups derives from two independent sources. The first is the distribution of phylogenetically informative characters or markers in extant and extinct taxa. The second is the stratigraphic or temporal sequence in which taxa occur as fossils. Neither source of data can be read uncritically, and both require interpretation. Phylogenies incorporate assumptions concerning rooting and models of evolution. The resulting trees are therefore inferences rather than data. Fossils require varying degrees of interpretation depending upon the nature of the material, and dates may be subject to large margins of error. For these reasons, it is often desirable to compare inferences by mapping cladograms onto stratigraphic range charts
"Over all 19 data sets, congruence was extremely high (Table 1). The average GER (Wills, 1999) for static first occurrence dates was 0.767, with the best data set being the Hadrosauridae (Horner et al., 2004; 0.956) and the worst being the Paraves (Turner et al., 2007; 0.558)."

" The least congruent data sets were the Paraves (Turner et al., 2007; GERt = 0.571), Stegosauria (Galton and Upchurch, 2004b; GERt = 0.611), Prosauropoda (Galton and Upchurch, 2004a; GERt = 0.720), and Ceratopsia (Xu et al., 2002; GERt = 0.755)."

Paraves is objectively calculated as the worst in terms of congruence. In fact, the article says that it is "indistinguishable from random". And that is because it is based on the incorrect dino-to-bird idea.

This is even worse when you consider the high congruence of dinosaurs in general:
Preliminary reanalysis of the 1,000 animal and plant “static” data sets utilized by Benton et al. (2000) and Wills (2007) yielded an average GER* of 0.688, with only 34% attaining a GER* > 0.975. This strongly suggests that the congruence of dinosaur phylogenies is better than that for a large sample of data sets across a range of other taxa.

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