ULTRASTRUCTURE OF ENIGMATIC PHYTOCLASTS (BANDED TUBES) FROM THE SILURIAN-LOWER DEVONIAN: EVIDENCE FOR AFFINITIES AND ROLE IN EARLY TERRESTRIAL ECOSYSTEMS

ULTRASTRUCTURE OF ENIGMATIC PHYTOCLASTS (BANDED TUBES) FROM THE SILURIAN-LOWER DEVONIAN: EVIDENCE FOR AFFINITIES AND ROLE IN EARLY TERRESTRIAL ECOSYSTEMS