(Wikipedia/ John Conway) Struthiomimus, an ostrich-like theropod dinosaur.
Cloning Dinos
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SEPTEMBER 08, 2008
April Holladay, HappyNews Columnist

Q: I heard from my science teacher that if scientists find the blood sample of a dinosaur they can bring back dinosaurs to life, is this true?
Zhina, Ottawa, Canada
Tap, tap, tap... The ostrich heard her young pecking to escape its shell. She adjusted her soft, feathery wings over the clutch, protecting eggs from blistering African sun and predator notice. Her long neck held her head at ground-level, just above the drab spread wings. Mother and clutch — almost undetectable. Eventually, the laboring 'chick' pecked a circular crack around the blunt end, opened the egg and climbed out. He lay panting while his surrogate mother lifted a wing slightly, and peered in. A dinosaur!
A: A scenaro from a sci-fi movie or a real possibility?
Your teacher said if we can find a dino blood sample. How do we find a fresh sample? We need near-perfect DNA for cloning to work, says biologist Theresa Mecklenborg http://tiger_spot.mapache.org/Biology/index.html , but the last dino died about 140 million years ago. A sample from an animal dead for more five days is useless for cloning.
Well, how about a fresh-frozen sample, assuming we found a dino that froze immediately on death? But dinosaurs lived in warm to hot lands where nothing froze. Already we've hit a snag so great that cloning success is not possible.
Your teacher set up a big if. But, even if we could find a fresh sample, could we bring dinos back to life? Again, extremely unlikely. We must clone both males and females to create a viable breeding population.
Also at present, our successful-cloning rate is dismal. Two hundred and seventy seven cloned sheep died before Dolly the sheep managed to survive. We tried to bring back rare Asian wild cattle, the gaur, but failed. (The gaur species is endangered.) Bessie the cow, did accept the gaur DNA, and created a gaur calf. But the calf died a few days after birth.
So, your teacher is perhaps theoretically correct. But we cannot bring dinosaurs back by cloning, at least at our present level of technology.
Further Reading:
Cloning: http://www.extinctanimal.com/cloning.htm, ExtinctAnimal.com
Cloning extinct animals: http://tiger_spot.mapache.org/Biology/extinct.html
(Answered Sep. 8, 2008)