When did the eukaryotes appear on the geological time scale , name the eon, era, period, mya? and why?

Eukaryotes appeared on the geological time scale during the Proterozoic Eon, in the Paleoproterozoic Era, specifically in the Mesoproterozoic Period, around 1.6 billion years ago (mya). This is based on fossil evidence and molecular studies that suggest the emergence of eukaryotic cells during this time period. Eukaryotes are believed to have evolved from prokaryotic ancestors through a process known as endosymbiosis, where one organism lives inside another and eventually becomes a permanent part of it. This significant event in Earth's history marked the beginning of complex multicellular life forms and paved the way for the diversity of life we see today.