Spira mirabilis in Heterostegina: evolutionary and ecological perspectives. (3rd October 2021)

• Record Type: Journal Article
• Authors: Benedetti, Andrea
• Is Part Of: Historical biology. Volume 33:Number 10(2021)
• Page Start: 2171
• Page End: 2181
• Publication Date: 2021-10-03
• Subjects: Nummulitids -- Heterostegina -- biometry -- evolutionary trends -- golden selection; Paleobiology -- Periodicals; Biology -- Periodicals; Evolution -- Periodicals; Paleontology -- Periodicals; Biology -- Periodicals; Paleontology -- Periodicals; Evolution -- Periodicals; 560.5
• DOI: 10.1080/08912963.2020.1776272
• Languages: English
• ISSNs: 0891-2963

Abstract

ABSTRACT: Morphometric analysis of the marginal spiral outline of Heterostegina populations belonging to the ocalana-matteuccii lineage reveals that it fully fit with a logarithmic spiral identified by two variables: the initial radius ( IRex ) and the radius increase ( Rinc ). Spirals tend to become more looser through time as observable also in well-known Mediterranean lineages. Rinc tends to increase along a phyletic line leading to the definition of a trend of neanic acceleration in Heterostegina, defined as the tendency of the marginal spiral to become looser. Ecophenotypical variations, with high value of Rinc in respect to coeval populations, may occur as for other routinely employed biometric values for nummulitids, but the investigated populations can be well-constrained in a Rinc-X bivariate plot, where X indicates the number of undivided chambers. The spiral outline, going looser, seems to tend become a golden spiral, a spiral defined by value of Rinc of 0.306, leading to a recognition of golden selection in Heterostegininae.