Fossil remains of a cell membrane component identified in rocks dating back about 1.6 billion years are opening a window into what scientists are calling a "lost world" of microscopic organisms that were the primordial forerunners of Earth's fungi, algae, plants and animals - including people.
These remains, researchers said on Wednesday, date to a time span during what is called the Proterozoic Eon that was crucial in the evolution of complex life but has been shrouded in mystery because of a spotty fossil record of the microscopic organisms that inhabited Earth's marine realm.
The newly identified fossils are of a rudimentary form of a steroid - a fat molecule that was an indispensable ingredient in cell membranes of pioneering members of a domain of now-dominant organisms called eukaryotes (pronounced yoo-KAR-ee-oats). Eukaryotes possess a complex cell structure including a nucleus that acts as a command and control center and subcellular structures called mitochondria that power the cell.
