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New multicellular marine macroalgae from the early Tonian of northwestern Canada

Maloney, Katie M.; Halverson, Galen P.; Schiffbauer, James D.; Xiao, Shuhai; Gibson, Timothy M.; Lechte, Maxwell A.; Cumming, Vivien M.; Millikin, Alexie E.G.; Murphy, Jack G.; Wallace, Malcolm W.; Selby, David; Laflamme, Marc

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Katie M. Maloney

Galen P. Halverson

James D. Schiffbauer

Shuhai Xiao

Timothy M. Gibson

Maxwell A. Lechte

Vivien M. Cumming

Alexie E.G. Millikin

Jack G. Murphy

Malcolm W. Wallace

David Selby

Marc Laflamme


Molecular phylogenetic data suggest that photosynthetic eukaryotes first evolved in freshwater environments in the early Proterozoic and diversified into marine environments by the Tonian Period, but early algal evolution is poorly reflected in the fossil record. Here, we report newly discovered, millimeter- to centimeter-scale macrofossils from outershelf marine facies of the ca. 950–900 Ma (Re-Os minimum age constraint = 898 ± 68 Ma) Dolores Creek Formation in the Wernecke Mountains, northwestern Canada. These fossils, variably preserved by iron oxides and clay minerals, represent two size classes. The larger forms feature unbranching thalli with uniform cells, differentiated cell walls, longitudinal striations, and probable holdfasts, whereas the smaller specimens display branching but no other diagnostic features. While the smaller population remains unresolved phylogenetically and may represent cyanobacteria, we interpret the larger fossils as multicellular eukaryotic macroalgae with a plausible green algal affinity based on their large size and presence of rib-like wall ornamentation. Considered as such, the latter are among the few green algae and some of the largest macroscopic eukaryotes yet recognized in the early Neoproterozoic. Together with other Tonian fossils, the Dolores Creek fossils indicate that eukaryotic algae, including green algae, colonized marine environments by the early Neoproterozoic Era.


Maloney, K. M., Halverson, G. P., Schiffbauer, J. D., Xiao, S., Gibson, T. M., Lechte, M. A., …Laflamme, M. (2021). New multicellular marine macroalgae from the early Tonian of northwestern Canada. Geology, 49(6), 743-747.

Journal Article Type Article
Acceptance Date Jan 8, 2021
Online Publication Date Mar 22, 2021
Publication Date Jun 1, 2021
Deposit Date Apr 30, 2021
Publicly Available Date Apr 30, 2021
Journal Geology
Print ISSN 0091-7613
Electronic ISSN 1943-2682
Publisher Geological Society of America
Peer Reviewed Peer Reviewed
Volume 49
Issue 6
Pages 743-747