Toward an understanding of gleicheniaceous fern evolution; organismal concept for an Eocene species from western North America.

Anatomically preserved fossil gleicheniaceous fern remains in carbonate marine concretions from Vancouver Island, British Columbia, Canada support the development of a whole plant concept for an Eocene species of Gleichenia , and provide data to develop the first organismal concept for an extinct species of Gleichenia from the Cenozoic fossil record. New information for completing the plant reconstruction includes anatomically preserved pinnule fragments with attached radial exindusinate sori of six to seven annulate sporangia containing trilete spores. While the overall pattern of evolution within Gleicheniaceae remains incompletely understood because well-documented fossils from pre-Cretaceous deposits are inconsistently preserved, this organismal plant concept strengthens evidence that all diagnostic features of the family Gleicheniaceae were present, and that essentially modern species were well-established and diversifying during the Cretaceous and Paleogene. • First whole plant reconstruction of a Cenozoic species of Gleichenia. • Characterized by both external morphology and internal anatomy. • Evidence of stems, frond fragments, and sori of sporangia containing spores. • Essentially modern species of Gleicheniaceae evolved no later than the Paleogene. • Family Gleicheniaceae is inconclusively present in pre-Cretaceous deposits. [ABSTRACT FROM AUTHOR]