Archaeplastida (Plant Lineage) Splits from Opisthokont Lineage. Around 1.65 billion years ago, a branch of protozoa, an advanced branch of the eukaryote cells, split into animals, plants, and fungi ancestors. These three separate lineages are the ancestors of modern plants, fungi and animals. 

These early branches were still microscopic and simple. Multicellularity did not appear immediately — but when cell adhesion and communication mechanisms evolved, it emerged repeatedly across different lineages, suggesting it is a powerful evolutionary strategy rather than a single destined outcome.

• 1.7 billion years ago: Plants diverge from the common protozoa ancestor.
• 1.5 billion years ago: Fungi and animal branch emerges.
• 1.3 billion years ago: Fungi diverge from the common fungi-animal ancestor.

Later animals evolve into the animal kingdom which includes mammals, birds, reptiles, amphibians, fish, insects, crustaceans, arachnids, echiniderms, worms, mollusks, and sponges.