A windpump (or drainage windmill) in Horsey, Norfolk, England.
"Look, there's a flock of cows!"
"Herd of cows, Dad."
"Heard of 'em? There's a whole flock right over there!"
"Dad, I'm hungry."
"Hi, Hungry, I'm Dad."
"Dad, can you make me a sandwich?"
"Poof. You're a sandwich."
Yoo-hoooo! Be a doll and add a funny thing.
Probably inaccurate as to how extinct creatures actually appeared, but, hey, looks cool. See also Science.
Unless you want your evil plan foiled, best not to leave them unattended.