The yale was first written about by Pliny the Elder in his Natural History. The creature passed into medievalbestiaries and heraldry, where it represents proud defense. It was used in the British Royal Family as a supporter of John, Duke of Bedford, and in England's Beaufort family. Margaret Beaufort's yale supporters can be seen over the gateways of Cambridge's Christ's College and St. John's College. There are also yales on the roof of St. George's Chapel in Windsor Castle.
The yale might have developed from a description of an Indian Water Buffalo, which is capable of moving its horns forward for defense. The name might be derived from Hebrew "yael", meaning "mountain goat".
References
Hrynkiw, Donna M., The Yale: Heraldic Beast (August 20, 1998)[1] (http://www.kwantlen.bc.ca/~donna/sca/yale/).