Here be giants
Wondering what other animals used to be giant? Here's a list of 10 of them.
That's much larger than today's six surviving sloth species, all of which live in trees and weigh less than 20 lbs. (9 kg).
Read more about the ground sloth.
A. pardinensis weighed about 220 lbs. (110 kg), roughly double the weight of its modern cheetah cousin (Acinonyx jubatus).
Read more about the giant cheetah.
Read more about the short-faced bear.
This otter (Siamogale melilutra) weighed 110 lbs. (50 kg) — about twice that of the modern-day South American giant river otter (Pteronura brasiliensis) and about four times the size of the Eurasian otter (Lutra lutra).
Read more about the ancient otter.
But K. biceae is only the second-largest penguin on record. The largest is the 37-million-year-old Palaeeudyptes klekowskii, which was 6.5 feet (2 m) tall and weighed a whopping 250 lbs. (115 kg).
Read more about the ancient penguin.
Read more about the giant kangaroo.
Read more about giant dragonflies.
It's distant relative, the orangutan isn't nearly as large. Male orangutans can weigh up to 300 lbs. (136 kg), and female orangutans weigh less than half that, according to Orangutan Foundation International.
Read more about the ancient ape.
Today's chinook salmon (Oncorhynchus tshawytscha) are much smaller, growing to about 2.3 feet (70 cm) long, according to Fishbase.org.
Read more about the giant salmon.