Geological Society of America

T110 Evolving Perspectives on the Tonian Biosphere and Environmental Change

Wednesday, 28 October 2020
10:00 AM - 12:00 PM
Meeting Rooms

POSSIBLE MULTICELLULAR GREEN ALGAE IN EARLY TONIAN MARINE ENVIRONMENTS

Paper number: T110-5
Program: Technical Sessions
Time: 11:00 AM – 11:15 AM

Authors

Katie Maloney Presenting Author
86 Elmira Drive, Hamilton, ON
Malcolm W. Wallace
University of Melbourne, Carlton
David Selby
Durham University, Durham
Marc Laflamme
University of Toronto Mississauga, Mississauga, ON
Galen Halverson
McGill University, Montreal, QC
James Schiffbauer
University of Missouri, Columbia, MO
Shuhai Xiao
Virginia Tech, Blacksburg, VA
Timothy M. Gibson
Dartmouth College, Hanover, NH
Maxwell Lechte
McGill University, Montreal, QC
Vivien M. Cumming
McGill University, Montreal, QC
Alexie Millikin
Yale University, New Haven, CT
Jack G. Murphy
Princeton University, Princeton, NJ

Abstract

Early eukaryotic fossils are crucial to understanding the evolution of the Earth’s biosphere and geosphere. Molecular clock estimates suggest that crown-group members of key algal lineages evolved and diversified by the Tonian Period, but this diversification is poorly reflected in the fossil record. Here we report newly discovered, centimeter-scale macrofossils from outer shelf marine facies of the ca. 950–900 Ma Dolores Creek Formation, Wernecke Mountains (northwestern Canada). These fossils, variably preserved by iron oxides and clay minerals, represent two distinct size classes. The larger cm-scale fossils feature unbranching thalli composed of uniform cells with differentiated cell walls and punitive holdfasts, while the smaller mm-scale specimens display branching. The fossils are likely green macroalgae making them among the oldest yet recognized in the fossil record, thereby filling a critical gap in the timeline of algal evolution. The Dolores Creek macroalgae, together with recently reported ca. 1000 multicellular chlorophyte from North China provide evidence that benthic green algae inhabited shallow marine habitats by the early Tonian Period.

Geological Society of America Abstracts with Programs. Vol. 52, No. 6

doi: 10.1130/abs/2020AM-354734

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