What extinct mammal genus is often cited as the largest known land mammal?

Paraceratherium is the extinct mammal genus often cited as the largest known land mammal.

This hornless relative of modern rhinoceroses lived across Eurasia during the Oligocene, roughly 34 to 23 million years ago. It had long, pillar-like legs, a very long neck, and a skull adapted for reaching leaves and other soft vegetation high above the ground.

Its exact size remains uncertain because no complete skeleton is known. Estimates commonly place large individuals around 4.8 metres at the shoulder and roughly 15–20 tonnes, although older reconstructions sometimes proposed substantially greater masses. The genus is therefore best described as one of the largest known terrestrial mammals, rather than an absolutely uncontested record-holder.

Paraceratherium fossils have been assigned to several named species and related genera, including Indricotherium and Baluchitherium. Many modern researchers treat some of those names as synonyms or closely related forms. Comparisons with giant proboscideans such as mammoths make “largest ever” depend on whether height, mass, or completeness of the fossil record is being measured.