Casey Luskin and the Frogamander, a Cautionary Tale

January 23, 2011 at 9:20 am (Discovery Institute)

With all the hoopla over at the DI about homoplasy I thought this post would be relevant. Gerobatrachus is one of my favorite fossil finds. Here’s an interesting post about it at Discovery Institute’s blog here . Here’s some of my own (hopefully constructive) criticism of this article.

Casey Luskin claims that

” ~75% of the character data conflict with the phylogenetic hierarchy in their tree.”

That is correct, but it can’t be taken as a measure of quality of their data set. The CI ( consistency index ) is strongly negatively correlated with the number of taxa and characters, the more of either the lower it gets. Furthermore, the original matrix this one was based on specifically maximized the number of characters that might conflict because it’s better not to rule things out beforehand, which further lowers the CI. You cannot compare the CI of different analyses based on different matrices as a result. Also, the ankle seems to go into a piece of matrix that remains in place. I’m fairly confident that we have all of the bones that were ossified in this area in this individual.


1 Comment

  1. Diogenes said,

    Thanks you for this informative post. (Yes I know it’s two years old; but better late then never.) Too many bloggers ignored Luskin’s hilarious frog attack. I am wondering what is your background: comparative anatomist, systematics, paleontology…? I hope you find time to post more.

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