Abstract
Abstract. Two morphometric methods are applied and compared for the analysis of suture lines in Early Carboniferous ammonoids of the superfamilies Pericycloidea, Girtyoceratoidea and Goniatitoidea. We analysed (1) classic metric data (proportions of the width and depths or heights of lobes and saddles) using multivariate statistic methods and (2) outline data of the external lobe and the ventrolateral saddle of the same ammonoid taxa using the elliptic Fourier analysis. Both methods lead to similar results and simultaneously demonstrate ontogenetic and phylogenetic trends of these ammonoids. Our results are consistent with three previously suggested evolutionary patterns: (1) a general decrease of the amplitude of lobes and saddles, (2) a proportional widening of the external lobe and (3) a heightening of the median saddle.
Highlights
The scientific branch of morphometrics, i.e. the quantitative investigation of biological shape variation (Bookstein, 1996), has a long history
We performed two types of analyses with respect to early Carboniferous ammonoid suture lines; a Fourier outline analysis was performed with two different data sets and one additional analysis was using metric data
Fourier outline analysis 1, which was done for overview purposes, was realized with the analysis of 109 suture lines of a sample of Early Carboniferous ammonoids
Summary
The scientific branch of morphometrics, i.e. the quantitative investigation of biological shape variation (Bookstein, 1996), has a long history. The description of the organisms by means of their shape and proportions allowed for a classification of biological objects; the study and evaluation of morphological characters enabled the development of a taxonomic hierarchy. The classic investigations of shape variation in organisms were mainly based on metric parameters. Francis Galton (Galton, 1883) proposed an approach towards a quantitative differentiation between human faces, later known as two-point shape coordinates or Bookstein shape coordinates (BCs). The methodology of this time faced the problem that the morphological characters and their relationships were difficult to analyse and only with the advent of multivariate morphometrics could these be statistically investigated (Mitteroecker and Gunz, 2009)
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