Growth of the enigmatic Ediacaran <i>Parvancorina minchami</i>

Analysis of length-frequency data using the ELEFAN (Electronic Length-Frequency Analysis) approach and software is widely used to quantify the growth, mortality, longevity, and related parameters of Recent marine animals. Here we analyze a sample ( n = 211) of the Ediacaran metazoan Parvancorina minchami Glaessner, 1958, from the Vendian siliciclastic marine deposits of the southeastern White Sea region, Russia. The results fit a von Bertalanffy equation with the parameters L ∞ = 2 cm, K = yr ⁻¹ (with t 0 not estimated) and an instantaneous rate of mortality ( M ) of 1.44 yr ⁻¹ , implying M / K ≈ 2, as commonly occurs in Recent small invertebrates. These parameter values also imply a longevity for P. minchami of about 4 yr. The concepts and approach used here, previously applied to an Ordovician trilobite and a Cambrian radiodont, suggest that inferences on growth, mortality, longevity, and related parameters can be obtained from suitable size-frequency samples of long-extinct metazoans, opening new vistas on their growth dynamics and functional roles in ancient ecosystems.