The Wooly rhino grew to 11 feet in length and stood 6 feet at its shoulders. It had a huge pair of horns that grew inline on its snout. The front horn grew to lengths in excess of 3 feet. Like modern rhinos, wooly rhinoceros had horns composed of keratin. They first appeared in the fossil record 1.8 million years ago and went extinct as recently as 10,000 years ago.