Answer: caballus
Explanation: caballus, were brought back to North America, first in the Virgin Islands, and, in 1519, they were reintroduced on the continent, in modern-day Mexico, from where they radiated throughout the American Great Plains, after escape from their owners or by pilfering (Fazio 1995).
It was the Duke of Wellington who finally gave Nappy the kick in the behind he had deserved for so long. Cheers to the duke!