1.8 billion years ago.
Mitochondria, which are thought to have originated from bacterial endosymbionts, were not present in the first eukaryotes. These early eukaryotes were likely single-celled organisms that lacked many of the organelles found in modern eukaryotic cells.
The first eukaryotes were unicellular organisms that evolved around 2 billion years ago, followed by the first terrestrial eukaryotes that emerged around 1.6 billion years ago. Between these events, there were significant biological and environmental changes, including the development of multicellularity and adaptations for life on land.
Prokaryotes were present for about 2 billion years before eukaryotes emerged. Eukaryotes are believed to have evolved around 1.5 to 2 billion years ago, while prokaryotes first appeared around 3.8 billion years ago.
Other eukaryotes may eat eukaryotes and some prokaryotes may eat eukaryotes.
Prokaryotes are believed to have appeared around 3.5 billion years ago, while eukaryotes are estimated to have evolved around 1.6 billion years ago. Therefore, prokaryotes are approximately 1.9 billion years older than eukaryotes.
2.1 billion
Single-celled organisms such as amoeba.
The first protists appeared around 1.5 billion years ago during the Precambrian era. These single-celled organisms were some of the first eukaryotes, containing a nucleus and other membrane-bound organelles. They played a crucial role in the evolution of complex life forms on Earth.
eukaryotes
The first eukaryotes are most likely to belong to the Protista kingdom. These are mostly multicellular organisms with the earlier ones including organisms like Kneallhazia solenopsae and many more.
Probably Protista, because there are evidences that suggests they were the first eukaryotes to be developed.
The chloroplasts in eukaryotes closely resemble cyanobacteria, as first noted by French scientist Andreas Schimper. Cyanobacteria are bacteria that produce energy for themselves through photosynthesis.