Harpagornis - A giant eagle
 

Harpagornis moorei was the largest known eagle to ever exist. This species lived in New Zealand and is thought to have gone extinct somewhere between 1400 and 1500 A.D.

Harpagornis weighed 10-14 kg. (22-30 pounds). It had a wingspan of at least 2.6 m. and some scientists believe that the wingspread could have even been 3 m., which is slightly over 9 feet.
Harpagornis preyed on the large flightless birds called Moas. It could come after them at speeds of as much as 80 km. (50 miles) per hour. The Harpagornis used one talon to seize the Moa by the pelvis. Then it killed the Moa by striking its head or neck with a talon from the other foot.
Fossilized remains of Harpagornis were first found 1n 1871 on Glenmark Estate, which was owned by a man named George Henry Moore. Julius von Haast described the fossil in 1872. He named the species after Moore.
Research done with DNA indicates that Harpagornis is most closely related to the Little Eagle (Hieraatus morphnoides) and the Booted Eagle (Hieraatus pennatus). Both of these species are much smaller than Harpagornis. Harpagornis is thought to have diverged from them between 700,000 and 1.8 million years ago. This time span is completely within the Pleistocene period. Thus Harpagornis seems to have a Pleistocene origin.
During the time of divergence, Harpagornis increased in weight to 10-15 times its original size. The increase (in proportion to the time frame) is the fast evolutionary weight increase of any known vertebrate.
Three complete skeletons of Harpagornis have been found. They are on display in these museums:

Otago Museum
Museum of New Zealand
Natural History Museum, London

Neal Robbins

P.S. The taxonomy of Harpagornis is:

Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Falconiformes
Family: Accipitridae
Genus: Harpagornis
Species: Harpagornis moorei