Precambrian biota from the Little Dal Group, Mackenzie Mountains, northwestern Canada

Abstract

Well preserved Precambrian algal microfossils and megafossils were recovered in the northern Mackenzie Mountains [Canada] from several levels and localities in a basinal, limestone-dominated rhythmite formation of the Little Dal Group. The microbiota includes the filaments Archaeotrichion, Taeniatum, and Siphonophycus, and the sphaeromorph acritarchs Kildinella, Trachysphaeridium, Nucellosphaeridium, and Chuaria circularis. The megafossils, all of probable algal affinities, comprise large carbonaceous ribbons assigned to the new vendotaenid species TAWUIA dalensis gen. et sp. nov. and the irregular compressions Moriana? antiqua and Beltina danai. The same formation has also yielded in dubiofossil probably representing traces on bedding planes made by small cylindrical, discoid, or spheroidal organisms, questionably referred to Bergaueria. The biota suggests a late Helikian to early Hadrynian age (1.1-0.8 Ga) for the Little Dal Group, and adds to the growing body of evidence for the existence of eucaryotic organisms at that time.