Repository logo
 

A Laurentian record of the earliest fossil eukaryotes

Published version
Peer-reviewed

Type

Article

Change log

Authors

Adam, ZR 
Skidmore, ML 
Mogk, DW 
Butterfield, NJ 

Abstract

The oldest evidence of eukaryotes in the fossil record comes from a recurrent assemblage of morphologically differentiated late Paleoproterozoic to early Mesoproterozoic microfossils. Although widely distributed, the principal constituents of this Tappania-Dictyosphaera-Valeria assemblage have not hitherto been recognized on Laurentia. We have recovered all three taxa from a shallow-water shale succession in the early Mesoproterozoic Greyson Formation (Belt Supergroup, Montana, USA). An exceptionally preserved population of Tappania substantially expands the morphological range of this developmentally complex organism, suggesting phylogenetic placement within, or immediately adjacent to, crown-group eukaryotes. Correspondence with Tappania-bearing biotas from China, India, Australia, and Siberia demonstrates an open-ocean connection to the intracratonic Belt Basin and, along with broadly co-occurring macrofossils Grypania and Horodyskia, supports the recognition of a globally expressed biozone. The Greyson Formation, along with contiguous strata in Glacier National Park, is unique in preserving all currently confirmed taxa of early eukaryotic and macroscopic fossils.

Description

Keywords

37 Earth Sciences, 3709 Physical Geography and Environmental Geoscience, 3705 Geology, 14 Life Below Water

Journal Title

Geology

Conference Name

Journal ISSN

0091-7613
1943-2682

Volume Title

45

Publisher

Geological Society of America
Sponsorship
Z. Adam was supported by the National Science Foundation Graduate Research Fellowship Program, the Lewis and Clark Fund for Exploration Research (NASA Astrobiology Institute and American Philosophical Society), the Tobacco Root Geological Society, the Belt Association, the D.L. Smith Fund, and a Geobiology Postdoctoral Fellowship from the Agouron Institute.