Wyvern?

Cockatrice:
Amongst the monsters with wings the Cockatrice and the Wyvern(Sax. wivere, a serpent) are frequently represented in heraldry. The differ from the groups of Griffins and Dragons, inasmuch as they have only two legs, and the hinder part of the body ends in a large and long tail. The Cockatrice is represented as having the head of a cock, but the tongue extended and barbed. Otherwise it is very similar to the wyvern, the essential difference being that the wyvern has the head of a serpent, but with the tongue extended and barbed. The frequency of such devices was due, no doubt, to the tales of travellers brought from the East, which had a special charm for many a designer of arms.
The Cockatrice, perhaps, when correctly drawn, should have the legs and feet of a cock-the Wyvern those of an eagle, but these details are seldom observed in representation.

from “A Glossary of Terms Used in Heraldry” (Parker, 1894)