MSM and GER calculations are a powerful and objective way to determine the level of fit between any proposed cladogram and the fossil record.
We saw earlier the GER values obtained by Wills et al (2008) for 19 dinosaur groups. You will recall that the Paraves values were the lowest on the list.
To understand the deep significance of the Wills et al study we need to look at the 19 groups (taxa) that were included.
The 19 number is made up of 17 dinosaur groups such as Sauropoda, Hadrosauridae etc. These have high GER scores.
The other two are bird related groups - the Turner et al (2007) Paraves study and the Senter et al (2007) Paraves + Oviraptorosauria study.
The GER for the Turner et al (2007) Paraves was .5579. The GER for the Senter et al (2007) Paraves + Oviraptorosauria was .6780.
These are exceptionally low values indicating low congruence.
Three things to note:
1. When analyzing a strictly dinosaur group (such as Hadrosauridae, Sauropoda etc) the GER value is "extremely high" according to the authors. This is not surprising. In those cases we are not even analyzing the dino-to-bird theory.
2. However when we analyze a bird group (such as Paraves) the congruence is "indistinguishable from random".
3. The best way to analyze the dino-to-bird theory would be to calculate the congruence for coelurosaurs or theropoda. In other words a grouping that includes dinosaurs and birds. Unfortunately the Wills et al study does not include any study like that. But the Pol and Norell (2006) study does. (I will elaborate on that in the next post).