title: Precambrian columnar stromatolite diversity: reflection of metazoan appearance.
abstract: Columnar stromatolites (organosedimentary structures built by bluegreen algae) show a marked decrease in diversity in the Late Precambrian; this decrease in diversity occurs at approximately the same time as the appearance of metazoans, 600 to 700 million years ago.
authors.forename: S M
authors.initials: SM
authors.lastname: Awramik