Ankylosaurus is a genus of armored dinosaur. Its fossils have been found in geological formations dating to the very end of the Cretaceous Period, about 68–66 million years ago, in western North America, making it among the last of the non-avian dinosaurs. It was named by Barnum Brown in 1908.

Possibly the largest-known ankylosaurid, Ankylosaurus is estimated to have been between 6 and 8 meters (20 and 26 ft) long and to have weighed between 4.8 and 8 tonnes (4.7 and 7.9 long tons). It was quadrupedal, with a broad, robust body. It had a wide, low skull, with two horns pointing backward from the back of the head, and two horns below these that pointed backward and down.

More Info: en.wikipedia.org