Paraceratherium, a gigantic, hornless rhinoceros, is one of the largest known land mammals that have ever existed, but its precise size is unclear because of the lack of complete specimens.[4] Its total body length was estimated as 8.7 m (28.5 ft) from front to back by Granger and Gregory in 1936, and 7.4 m (24.3 ft) by the palaeontologist Vera Gromova in 1959,[33] but the former estimate is now considered exaggerated.