GIANT SCALES, TINY SCALES & SIMILAR SCALES: A REVIEW OF THE SYNUROPHYCEAE IN THE FOSSIL RECORD

• Published in: Phycologia (Oxford) Vol. 56; no. 4; p. 173
• Main Authors: Siver, P A, Lott, A M, Wolfe, A P
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis Ltd 01.08.2017
• Subjects: Algae; Cell surface; Climate; Components; Cretaceous; Endangered & extinct species; Eocene; Evolution; Fossils; Greenhouses; History; Inland waters; Jurassic; Lakes; Miocene; Organizations; Palaeocene; Paleocene; Phylogeny; Rib
• ISSN: 0031-8884; 2330-2968

Synurophyceae are heterokont algae characterized by distinctive siliceous scales that cover the surface of the cell, and are ecologically important in inland waters. The evolutionary history of the group is poorly known largely due to a sparse fossil record. Recently, scales representing over 55 synurophyte species have been uncovered from four geologic localities representing the Paleocene, Eocene and Miocene. The vast majority of fossils have come from the Giraffe fossil locality, a maar lake that existed in the Canadian Arctic during the middle Eocene under a warm greenhouse climate. The authors combined a five-gene molecular phylogeny with the fossil remains to explore evolutionary trends within the group, with a focus on the siliceous components. Based on these results, the group originated in the Jurassic approximately 157 million years ago (Ma), with the keystone genera Mallomonas and Synura diverging during the Early Cretaceous at 130 Ma. Mallomonas further splits into two major subclades, signaling the evolution of the V-rib believed to aid in the spacing and organization of scales on the cell covering.