Males are usually 71 to 76 centimetres (28 to 30 in) tall at the withers, and weigh on average 27 to 40 kilograms (60 to 88 lb). Females tend to be smaller, with shoulder heights ranging from 66 to 71 centimetres (26 to 28 in) and weights from 25 to 34 kilograms (55 to 75 lb), although weights can be above and below these average weights. Written evidence of the historic time, the Vindolanda tablets (No 594), from the early period of Roman occupation demonstrates that the occupying troops from Continental Europe either had with them in the North of England, or certainly knew of the vertragus and its hunting use.All modern pedigree Greyhounds derive from the Greyhound stock recorded and registered first in private studbooks in the 18th century, then in public studbooks in the 19th century, which ultimately were registered with coursing, racing, and kennel club authorities of the United Kingdom.