Answer: Genetic data suggest that multicellular animals evolved around 1000 million years ago; this is supported by fossil embryos from rocks in China that date back 600 million years.
Step-by-step explanation:
The basic timeline is a 4600 million year old Earth with: 4000 MY (million years) of simple cells; 3000 MY of photosynthesis; 2000 MY of complex cells; 1000 MY of multicellular life; 600 MY of simple animals; 500 MY of fish and proto-amphibians; 475 MY of land plants; 400 MY of insects and seeds; 360 MY of amphibians; 300 MY of reptiles; 200 MY of mammals; 150 MY of birds; 100 MY of flowers; and 65 MY since the non-avian dinosaurs died out.