When did animal life begin on earth?
Earlier than 650 million years ago (mya)
I had collected the following data for endnotes (p155) to my essay "10 Esoteric Science about universe and creation", in my book "Faiths and proximate truths (2010);
Unicellular to multicellular evolution:2 billion years ago - 600 million years ago (mya).
Sea life: 650 mya.
Leg-bearing worms: 570 mya.
Movement of sea-animals to land: 400 - 385 mya.
Insects: 359 - 299 mya.
Mini-wnged dinosaurs: 160 mya.
Flying squirrels: 125 mya.
Bats: 50 mya.
Anthropoid (resembling human):
Female Ida ( Germany): 47 mya.
Ganea megacanina (Asia): 39 mya.
Hominid Ardi: 4.4mya and Lucy: 3,2 mya (Africa)
The readers could update these data for corrections and omissions, if any. These are all 2-sd and 3-sd approximations, with million years as unit of time.