When it went extinct: About 11,000 years ago
How: Hunting by humans
Where it lived: The Americas
Size: As long as 20 feet, up to 9,000 pounds
Diet: Ate plants but also scavenged for meat
Random fact: Had claws as long as 20 inches
Why we might be able to bring it back: DNA samples found in fossil dung in Utah
Cuban red macaw
When it went extinct: Last sightings in the late 1800s
How: Hunting, nesting trees felled to capture young birds for the pet trade
Where it lived: Cuba
Size: Approximately 20 inches long
Random fact: Even though its meat was said to smell and taste bad, people still dined on red macaw.
Why we might be able to bring it back: Specimens in Cuba contain DNA samples.
New Zealand giant moa
When it went extinct: Circa A.D. 1400
Where it lived: New Zealand
Size: As tall as 8 feet, up to 500 pounds
Diet: Probably fed on plants
Random fact: The moa did not have wings.
Why we might be able to bring it back: DNA found in fossil eggs and feathers in New Zealand
Tasmanian tiger (also known as a thylacine)
When it went extinct: Last recorded sighting in the 1930s
How: Hunting, habitat loss
Where it lived: Tasmania, Australia, and New Guinea
Size: Over 4 feet long, around 75 pounds
Diet: Preyed on kangaroos, small rodents, birds
Random fact: People who saw the animal reported that it could open its jaw nearly 180 degrees wide.
Why we might be able to bring it back: Cloning is a possibility with preserved DNA from a specimen at the Australian Museum.
When it went extinct: Circa at 10,000 B.C.
How: Probably hunting by humans
Where it lived: North and South America
Size: Around 6 feet long, up to 900 pounds
Diet: Preyed on such mammals as bison, deer, horses
Random fact: It's the official state fossil of California.
Why we might be able to bring it back: DNA is preserved in bones at the La Brea Tar Pits in Los Angeles.
When it went extinct: 1914
How: Hunting, habitat destruction
Where it lived: North America
Size: About 15 to 17 inches long
Diet: Seeds, worms, insects
Random fact: The last known bird, named Martha, died at the Cincinnati Zoo.
Why we might be able to bring it back: There are some 1,500 preserved passenger pigeon specimens with extractable DNA.
When it went extinct: Late 1600s
How: Mainly because on the island where it lived, newly introduced species like dogs ate chicks and eggs.
Where it lived: Mauritius
Size: About 3 feet tall
Diet: Fruit, seeds
Random fact: Lived only on the small island of Mauritius, east of Madagascar in the Indian Ocean
Why we might be able to bring it back: Two skeletons have been found containing DNA samples.
When it went extinct: About 3,700 years ago
How: Hunting, habitat loss due to climate change
Where it lived: Parts of northern Asia, Europe, and North America
Size: 9 to 11 feet tall, about 1,400 pounds
Diet: Grass and other plants
Random fact: Remains of a 37,000-year-old woolly mammoth calf were found in Russia.
Why we might be able to bring it back: DNA exists in frozen soft tissue.