A vaucheriacean alga from the middle Neoproterozoic of Spitsbergen: implications for the evolution of Proterozoic eukaryotes and the Cambrian explosion

Butterfield, N. J. (2004) A vaucheriacean alga from the middle Neoproterozoic of Spitsbergen: implications for the evolution of Proterozoic eukaryotes and the Cambrian explosion. Paleobiology, 30. pp. 231-252. ISSN ISSN: 0094-8373

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Abstract

A morphologically diverse assemblage of organic-walled fossils from the middle Neo- proterozoic Svanbergfjellet Formation, Spitsbergen, is identified as a monospecific assemblage rep- resenting the Gongrosira-phase of a vaucheriacean xanthophyte alga. As such, it provides a range of additional criteria with which to identify fossil vaucheriaceans and confirms the identification of Palaeovaucheria in the Mesoproterozoic Lakhanda Formation. Pronounced taxonomic inflation, through the practice of form-taxonomy, suggests that overall estimates of eukaryotic diversity in the Proterozoic need to be adjusted downward. Combined with positive evidence for low levels of speciation and extended stasis, pre-Cambrian eukaryotes are seen to evolve at a fundamentally lower rate than their Phanerozoic counterparts. This slower turnover accounts for the "delayed" appearance of animals without appeal to external triggers or constraints. The Cambrian acceler- ation of evolutionary rates was a direct consequence of newly introduced animals, whereas the much slower overall rates of the Proterozoic imply an absence of earlier metazoans.

Item Type:	Article
Uncontrolled Keywords:	2004 AREP 2004 P IA44A IA46
Subjects:	04 - Palaeobiology
Divisions:	04 - Palaeobiology
Journal or Publication Title:	Paleobiology
Volume:	30
Page Range:	pp. 231-252
Depositing User:	Sarah Humbert
Date Deposited:	29 Jun 2015 17:12
Last Modified:	29 Jun 2015 17:17
URI:	http://eprints.esc.cam.ac.uk/id/eprint/3345

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