Hi Fred, It is interesting that you are proposing to toss out CS completely in morphometrics, beyond its is function to bring the shape configurations to unit size during superimposition. In own experience (mostly derived from 3D microCT scans of mouse skulls and embryos), I have yet to see any set of landmark derived CS NOT to be highly correlated (>.9) with actually body weight information we collect from these organisms. In my experience, centroid sizes that are derived from biologically correctly scaled coordinate data is no worse (or better) than any size proxy that morphologist derive from skeletons like articular surface areas or volumes, or geometric means of linear measurements etc. Yes, for most cases landmarks are arbitrary, but so are the linear measurements. Any linear measurement any one claims to be reliably repeated can be represented by two landmarks.
In my experience the main issue with the centroid size is that sometimes (often?) people do not scale them at all (regardless they are 2D or 3D derived) into biologically relevant units, such as mm or cm that we can make sense of like the mm's we measure on calipers, or osteometry boards. Same set of landmarks derived from two pictures of the same skull (one scaled by the pixel size, the other in pixel coordinates) are going to give CS estimates that are orders of magnitude different from each other. When there is that methodological inconsistency about explicitly defined units for coordinate data, I am not sure how keeping the size in the analysis is going to help. On Saturday, October 4, 2025 at 7:42:58 PM UTC-7 fred bookstein wrote: > Sorry for the sheer bulk of this email, folks. My communication these days > is restricted to screen grabs from my iPhone. Fred B. > > -- You received this message because you are subscribed to the Google Groups "Morphmet" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/morphmet2/c6f823e1-e8cc-4b44-829f-fb3d4e74591bn%40googlegroups.com.
