The crossword solutions for the term LINE SEGMENT TIME are ERA, which stands for 'Eon of Reorganized Atomic structure'. ERA is a geological time period that began about 2.5 billion years ago and lasted until about 541 million years ago. It is the longest of the three divisions of the Proterozoic Eon. During this time, the Earth's atmosphere changed from anoxic to oxygen-rich, and the first multicellular organisms appeared.