Anoplotherium is the type genus of the extinct Palaeogene artiodactyl family Anoplotheriidae, which was endemic to Western Europe. It lived from the Late Eocene to the earliest Oligocene. It was the fifth fossil mammal genus to be described with official taxonomic authority, with a history extending back to 1804 when its fossils from Montmartre in Paris, France were first described by the French naturalist Georges Cuvier. Discoveries of incomplete skeletons of A. commune in 1807 led Cuvier to thoroughly describe unusual features for which there are no modern analogues. His drawn skeletal and muscle reconstructions of A. commune in 1812 were amongst the first instances of anatomical reconstructions based on fossil evidence. Cuvier's contributions to palaeontology based on his works on the genus were revolutionary for the field, not only proving the developing ideas of extinction and ecological succession but also paving the way for subfields such as palaeoneurology. Today, there are four known species.

Anoplotherium was amongst the largest non-whippomorph artiodactyls of the Palaeogene period, weighing on average 115 kg (254 lb) to 271 kg (597 lb) and measuring at least 2.5 m (8 ft 2 in) in head and body length and 1.25 m (4 ft 1 in) in shoulder height. It was an evolutionarily advanced and unusual artiodactyl, sporting three-toed feet in certain species like A. latipes, a long and robust tail, and a highly-developed brain with strong support for both sense of smell and sensory perception. Its overall robust build may have allowed it to stand bipedally to browse on plants at greater heights, reaching approximately 3 m (9.8 ft) tall, effectively competing with the few other medium to large herbivores it lived with. The full extent of its bipedalism needs to be confirmed by more research, however. The larger, two-toed A. commune and slightly smaller, three-toed A. latipes may be sexual dimorphs in that the former is female and the latter male, but this idea remains speculative. Its closest relative was Diplobune, which similarly is hypothesized to have had specialized behaviours.

The artiodactyl lived in western Europe back when it was an archipelago that was isolated from the rest of Eurasia, meaning that it lived in an environment with various other faunas that also evolved with strong levels of endemism. Its exact origins are unknown, but it arose long after a shift towards drier but still subhumid conditions that led to abrasive plants and the extinctions of the large-sized Lophiodontidae, achieving gigantism and establishing itself as a dominant herbivore throughout the entirety of the western European region given its abundant fossil evidence.

Its success was abruptly halted by the Grande Coupure extinction and faunal turnover event in the earliest Oligocene of western Europe, which was caused by shifts towards further glaciation and seasonality. Tropical and subtropical forests were rapidly replaced by more temperate environments, and most ocean barriers previously separating western Europe from eastern Eurasia closed, allowing for large faunal dispersals from Asia. Although the specific causes are uncertain, Anoplotherium was likely unable to adapt to these major changes and succumbed to extinction.

While Georges Cuvier knew about fossil bones from the gypsum quarries of the outskirts of Paris (known as the Paris Basin) as early as at least 1800, it was not until 1804 that he would describe them. After describing Palaeotherium, he wrote about the next set of fossils that he was able to discern as being different from Palaeotherium based on dentition form, including the apparent lack of canines that left a large gap between the incisors and premolars. He observed that the hemimandible (half a mandible) had three lower incisors instead of four incisors or none which he said characterized other "pachyderms". Cuvier, basing the name on its apparent lack of suitable arms and canines for offensive attacks, erected the name Anoplotherium.

The genus name Anoplotherium means "unarmed beast" and is a compound of the Greek words αν- (an, 'not'), ὅπλον (hóplon, 'armor, large shield'), and θήρ (thēr, 'beast, wild animal').

Cuvier named three species of Anoplotherium in the same year, the first of which was the "sheep-sized" A. commune and the other three of which were "smaller species" that he named A. medium, A. minus, and A. minimum. The etymology of the species name A. commune refers to how "common" fossils of the species were while the etymologies of the other two species were based on sizes compared to A. commune. He also attributed a cloven hoof (or didactyl hoof) to A. commune since the specimen appeared to be large-sized. He thought that Anoplotherium had didactyl hooves instead of tridactyl hooves, which would have separated it from Palaeotherium. Based on the hooves and dentition, he concluded that Anoplotherium was similar to ruminants or camelids. However, in 1807, Cuvier found out that Anoplotherium commune had three toes on its hind limbs, although the third index toes were of smaller sizes compared to the other two.

In 1807, Cuvier wrote about two incomplete skeletons that were recently uncovered, although the first was partially damaged because it was not collected carefully (which he expressed as having frustrated his understanding of the skeletal anatomy of Anoplotherium initially). The first skeleton, found in the quarries of Montmartre in the commune of Pantin, helped to confirm Cuvier's earlier diagnoses of Anoplotherium as correct. The embedded skeleton was the size of a small horse and helped to confirm the large didactyl feet and the 44 total teeth that it had (11 in each side of its jaw). It also had 11 complete ribs and a fragment of a 12th, matching with the number of ribs of camelids. The most surprising element to Cuvier, however, was the enormous tail with 22 vertebrae in the skeleton, a feature that he said he would not have known about previously, as there are no modern analogues of the elongated and thick tail in any large quadrupedal mammal.