By animal I mean it should have legs, either two, four, six, or more. I'm excluding Bacteria or other simple celled (precursors?) of life.
My best bet would be Cockroaches. They have been around for 400 million years, and hardly changed. Incredibly adaptable, able to survive flood, by swimming, can hold their breath underwater for 40 minutes. Survive fire and drought, able eat just about anything. They can run about 60 inches a second, ....proportionately thats 3 times as fast as a Cheeta, and they are less than 2" long.
But their top survival factor in my book is that they are able to live after a radiation dose of
105,00 rems, us humans can only withstand a onetime dose of 5 rems! Yet they hate Catnip and
Garlic, and run away from that.
Beware the new species of Cockroach just discovered in Borneo, living alongside a number of
new species there. They are over 4 inches long!
Lets hope they stay there.
