He is just over 2 2/3 times as tall as KneeHi, the Guinness World Record holder for shortest donkey.

[1] Romulus is 20–21 years old and has been measured at 17 hands (68 inches, 173 cm) from hooves to withers.

[4] American mammoths were developed and utilized for their potential to produce large mules when cross-bred with horses.

[4][5] On February 8, 2013, Romulus was measured for the Guinness Book of World Records.

[5] His paperwork was received in London and certified by Guinness World Records on May 13, 2013.