Figure 8
From: Parallel evolution controlled by adaptation and covariation in ammonoid cephalopods
Multivariate analysis of the eight measured shell parameters. Results of the principal component analysis (PCA) based on the eight measured shell parameters. The PCA was done on a correlation matrix. The first three principal components axes account for about 80% of the total variation in shell morphology. Vectors of shell characters (length and direction compared to the PC axes) revealed that variation on PC1 is mainly associated with Dmx, WSC, NLb/OLb, FCI and UWI, PC2 with WER and IZR, and PC3 with WSC.