why did the romans use an eagle as a symbol
Aquila (Roman) The eagle was extremely important to the Roman military, beyond merely being a symbol of a legion. A lost standard was considered an extremely grave occurrence, and the Roman military often went to great lengths to both protect a standard and to recover it if lost; for example, see the aftermath of the Battle of the Teutoburg Forest, where the Romans spent decades attempting to recover the lost standards of three legions.
Coat of arms of Mexico The coat of arms of Mexico (Spanish: Escudo Nacional de MÃ©xico, literally "national shield of Mexico") depicts a Mexican [golden] eagle perched on a prickly pear cactus devouring a rattlesnake.[1] The design is rooted in the legend that the Aztec people would know where to build their city once they saw an eagle eating a snake on top of a lake.[1] The image has been an important symbol of Mexican politics and culture for centuries. To the people of Tenochtitlan, this symbol had strong religious connotations, and to the Europeans, it came to symbolize the triumph of good over evil (with the snake sometimes representative of the serpent in the Garden of Eden).