The Nonius breed owes its name to its foundation sire, though since his male descendants share his name, he is called \Nonius Senior.\ Nonius was born in 1810 in Calvados, Normandy. His sire was the Thoroughbred Arion, and his dam was a Norman mare; an Anglo-Norman horse. He was captured from the French Stud at Rosiers aux Salines during the Napoleonic Wars and brought to Mezohegyes in 1816.
Journal des Haras 10/1837-03/1838 adds Nonius dam was by a Thoroughbred stallion. He was not 3/8 Thoroughbred but a half-bred Thoroughbred.
He was sent to Rosières as part of a testing about young horses'growth regarding climate adaptation. The inspectors reports read as follows: tall colt, but not beautiful and badly proportioned, not a stallion prospect, kept for experience