Wyvern

A wyvern (/ˈwaɪvərn/ WEYE-vərn, sometimes spelled wivern) is a legendary creature with a dragon's head and wings, a reptilian body, two legs, and a tail. A sea-dwelling variant dubbed the sea-wyvern has a fish tail in place of a barbed dragon's tail.

The wyvern in its various forms is important to heraldry, frequently appearing as a mascot of schools and athletic teams (chiefly in the United States and United Kingdom). It is a popular creature in European and British literature, video games, and modern fantasy. The wyvern is often (but not always) associated with cold weather and ice, and it will sometimes possess a venomous bite and rarely have the ability to breathe fire.

The usual spelling wyvern is not attested before the seventeenth century as "winged two-footed dragon". It is an alteration of Middle English (attested thirteenth century) wyver, from Old French wivre (cf. French guivre and vouivre), itself from Latin vīpera, meaning 'viper', 'adder', 'asp'.

The design of the wyvern to have derived from the figure of the dragon encountered by Trajan's legions in Dacia. It may be the origin of the red dragon of Wales and the golden dragon of the Kingdom of Wessex carried at the Battle of Burford in AD 752.

The wyvern has often been confused with the dragon, due to the similarities between them and due to the wyvern being a lesser-known mythical creature. In the Middle Ages, no clear distinction was made between the two. Since the sixteenth century, in English, Scottish, and Irish heraldry, the key distinction has been that a wyvern has two legs, whereas a dragon has four; however, this distinction is not generally observed in the heraldry of other European countries, where two-legged dragons are entirely acceptable.

...
Wikipedia