In the last three posts of this ongoing series, we’ve begun picking apart McLain et al’s 2018 ICC paper that claimed, based in part on baraminology, that dinosaurs had feathers. The paleontology we will leave for more qualified people, but I know of at least one researcher working on that problem. We will, instead focus on the baraminology. As we’ve seen in the last few posts, the deeper we dig into the baraminology of just one dataset, the more problems we find. That is also true of this weeks subset of the Brusatte dataset.
In figures 26 and 27, McLain et al split the Ornithomimosaurs, Alvarezauroids and the more “basal” Coelurosaurs. I imitated this dataset exactly, leading to twenty-six taxa. One hundred and two characters were used. Bootstrapping values were medicocre. Some were quite strong, but in both BARCLAY and BDISTMDS many were in the seventies and eighties, with quite a few dropping to the fifties and even forties in terms of percentages. These values would seem to hint that, at least a few of these taxic comparisons, are quite weak. This, of course, assumes that bootstrapping is worth the paper its written on, because, its not. But its part of the method so we will hold the method to its own standards and again ask why McLain et al did not report bootstrapping values? That’s something I’ve never gotten an answer to.
Having examined the bootstrapping values, I attempted to duplicate the McLain et al results. Interestingly, the two graphs differed, quite significantly.
Note that that the BARCLAY program produces a graph with significantly less discontinuity and splits the two groups that had previously been joined. Also, there is more continuity between the top three groups than there was in BDISTMDS. These results represent a running theme in BARCLAY. It seems to make a habit of detecting less discontinuity than BDISTMDS. That could be a good or bad thing, depending on whether the discontinuity actually exists. However, given that 45% of the time BDISTMDS failed to find discontinuity when it existed according to Wood, BARCLAY finding it even less is at least cause for concern.
The dataset was then run again at 85% taxic relevance, simply to test the data. Increasing the relevance by ten percent cut the number of characters by nearly 90%, down to a mere 16. Unsurprisingly with so few characters, it also created a messy output graph, in both BDISTMDS and BARCLAY. In this instance, BARCLAY detects lest continuity than BDISTMDS but with how few characters are used, I doubt much can be drawn from these two graphs.
Since the graphs are not terribly helpful here, we need to look at the MDS plots. Keep in mind, the MDS are completely arbitrary, but they’ve been incorporated into the method so we have to run them. The MDS plot for BDISTMDS matched the McLain et al paper, much as was expected. The BARCLAY MDS also looked fairly similar to the BDISTMDS plot as you can see below.
Notably, these results lack the tetrahedral geometry we observed in the last two breakdowns of figures from the paper. That means that, according to the method, these two MDS plots represent valid data. However, despite the BARCLAY graph showing separation between three groups, the separation is not evident, except for the three species at the top of the graph, who do split away from the rest. Examining the MDS plots for 85% relevance is equally unclear.
Again, the MDS at 85% relevance is a clump with no obvious groupings. This might be used to argue that these species are all the same kind. However, given I don’t think any creationist actually believe that, I think the best deduction from this particular set of data is its useless. There are too many potential kinds and too many question marks and missing data in the dataset. However, we will continue to work through the Brusatte dataset next week to see if anything valuable can be gleaned from it.
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In His Image 