Wyvern is made between the two. Since the sixteenth century, in English, Scottish, and Irish heraldry, the key difference has been that a wyvern has two legs, whereas a dragon has four. However, this distinction is not commonly observed in the heraldry of other European countries, where two-legged dragon-like creatures being called dragons is entirely acceptable. In the modern fantasy genre, there is little differentiation between dragons and wyverns, with two-legged, magical reptilian creatures all likely to be referred to as "dragons" without any differentiation between types. Wyverns, when present as creatures distinct from dragons, tend to appear as less magical
Mexican heraldry of these rules is a key to the art of heraldry. This system was adapted to Mexican society by incorporating flora and fauna native to Mexico. Another conspicuous difference between Mexican heraldry and European heraldry is the absence of a helm surmounting the shield. Most traditions of Mexican heraldry came from Hispanic or Spanish origin from regions in Spain or Portugal, predominating heraldry of Castilian, Basque or Galician, in second place heraldry of Catalan and Valencian origin. Other common heraldic traditions in Mexico came from French, Italian, German and Polish origins. The most recent heraldic influences, since 1943, are of