Sometimes the data has to be interpreted…

Yesterday we looked at the reduction of the postorbital and postfrontal in basal cynodonts and their predecessors among the gorgonopsids and theerocephalians. And for those who got there early, a late addition found the missing taxon I was looking for.

Figure 1. Sarctonus data from two different sources -- and they don't quite match.  Here the area at the base of the postorbital is missing, presumed to be squamosal in the lower Bystrow drawing, but never that way in any sister taxa. Upper drawing by Gebauer in two sizes, traced off of mandible and skull, which differ.

Figure 1. Sauroctonus data from two different sources — and they don’t quite match. Here the area at the base of the postorbital is missing — but filled in without being grayed out, presumed to be squamosal in the lower Bystrow drawing, but never that way in any sister taxa. Upper drawing by Gebauer in two sizes, traced off of mandible and skull, which differ in size but at least there is no jugal/squamosal suture shown.  Who knows which is right? Blue color marks typical jugal extent.

Today we’ll look at data that appears great, but a little experience tells you it’s not all there. In Sauroctonus (Fig. 1) it looks like we have a squamosal contributing to the base of the postorbital bar. But sister taxa don’t do that.

Sure, the easy answer is to go visit the specimen
But here I’ve done what I want to do without weeks of planning, a few day’s worth of jetting around, and thousands of dollars in expenses. Does this problem move this taxon up or down the tree a node or two? Doubtful, so why not go with what you’ve got?

Yes, there’s great data and terrible data out there. You have to trust a single source of data, but when given the opportunity to make comparisons, go ahead and test one against the other and their sisters. Sometimes the data is a poor half-a-century-old drawing. Sometimes you take what you can get and make corrections later.

Keep pushing. It will all work out in the end.

References
Bystrow AP 1955. A gorgonopsian from the Upper Permian beds of the Volga. Voprosy Paleont., 2: 7-18.
Gebauer EVI 2007. Phylogeny and Evolution of the Gorgonopsia with a Special Reference to the Skull and Skeleton of GPIT/RE/7113 (‘Aelurognathus?’ parringtoni). PhD Dissertation, Eberhard-Karls University at Tübingen. Online here.

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