Doedicurus, from Ancient Greek δοῖδυξ (doîdux), meaning "pestle" and oυρά (ourá), meaning "tail", is an extinct genus of glyptodont from South America containing one species, D. clavicaudatus. Glyptodonts are a member of the family Chlamyphoridae, which also includes some modern armadillo species, and they are classified in the superorder Xenarthra alongside sloths and anteaters. Being a glyptodont, it was a rotund animal with heavy armor and a carapace. Averaging at an approximate 1,400 kg (3,100 lb), it was one of the largest glyptodonts to have ever lived. Though glyptodonts were quadrupeds, large ones like Doedicurus may have been able to stand on two legs like other xenarthrans. It notably sported a spiked tail club, which may have weighed 40 or 65 kg (88 or 143 lb) in life, and it may have swung this in defense against predators or in fights with other Doedicurus at speeds of perhaps 11 m/s (40 km/h; 25 mph).

Doedicurus was likely a grazer, but its teeth and mouth, like those of other glyptodonts, seem unable to have chewed grass effectively, which may indicate a slow metabolism. Doedicurus existed during the Pleistocene. Before this, South America had been isolated from the rest of the world, but the formation of the Isthmus of Panama allowed North American fauna to invade South America in the Great American Interchange, including big cats, bears, proboscideans, camelids, and horses. Doedicurus seems to have inhabited the relatively cold and humid Chaco-Pampean plains of northeastern Patagonia. It may have been the latest-surviving glyptodont, with remains suggested to date to 8,000–7,000 years ago during the middle Holocene, though these dates have been questioned. It may have gone extinct due to some combination of human hunting and climate change.

The animal was first described by British paleontologist Richard Owen in 1847, the fifth glyptodont species described after Glyptodon clavipes, G. reticulatus, G. tuberculatus (now Panochthus), and G. ornatus (now Neosclerocalyptus). The type specimen was a partial tail which seemed to indicate a massive club, so Owen assigned the name G. clavicaudatus (the species name deriving from Latin meaning "club-tailed"). In 1874, German zoologist Hermann Burmeister classified it into its own genus as Doedicurus clavicaudatus, the genus name deriving from Ancient Greek δοῖδυξ "pestle" and oυρά "tail".

Doedicurus was a glyptodont, most closely related to modern armadillos, thus a member of the superorder Xenarthra (along with sloths and anteaters) endemic to South America. Glyptodonts were classified into the family Glyptodontidae. Through the 19th and 20th centuries, new species and genera were described on the basis of minute or debatable differences, and the total diversity had reached 65 genera with 220 species. In 1997, Malcolm C. McKenna and Susan K. Bell in their comprehensive revision of mammal taxonomy assigned all glyptodonts to the superfamily Glyptodontoidea, which included the families Pampatheriidae, Palaeopeltidae, and Glyptodontidae. Doedicurus was classified into Glyptodontidae in the subfamily Doedicurinae, alongside Eleutherocercus, Prodaedicurus, Comaphorus, Castellanosia, Xiphuroides, Daedicuroides, and Plaxhaplous.

In 2016, ancient DNA was extracted from the carapace of a 12,000 year old Doedicurus specimen, and a nearly complete mitochondrial genome was reconstructed (76x coverage). Comparisons with those of modern armadillos revealed that glyptodonts diverged from tolypeutine and chlamyphorine armadillos approximately 34 million years ago in the late Eocene. This prompted moving them from their own family, Glyptodontidae, to the subfamily Glyptodontinae within the extant Chlamyphoridae. Based on this and the fossil record, glyptodonts would have evolved their characteristic shape and large size (gigantism) quite rapidly, possibly in response to the cooling, drying climate and expansion of open savannas.

Cladogram of glyptodonts after Barasoain et al. 2022:

Glyptodonts have hypsodont dentition, and the teeth also never stopped growing in life, so they are assumed to have fed predominantly on grass. However, they have unusual teeth compared to those of other mammals, featuring three lobes (except for the first two teeth, which have the usual two lobes). The tooth core is made of osteodentine, which is surrounded by a layer of orthodentine, and capped off by cementum instead of enamel. Some of the orthodentine became exposed over time as the cementum was worn away, producing a file-like surface to better process grass, similar to the hard dentine and cementum eventually protruding through the enamel of horse and cattle teeth.

Glyptodonts have eight cheek teeth, and, like bovines, completely lack canines and incisors. Nonetheless, Doedicurus and other large glyptodonts appear to have had a markedly reduced gape, and the teeth have relatively small grinding surfaces, which indicate they were incapable of thoroughly chewing food. This may have been caused by the increasing size of the muscles to support the head and neck as the armor in this region became heavier and heavier, displacing the chewing muscles to less mechanically efficient positions. This is odd as thoroughly grinding grass is very important in maximizing nutrient absorption, and such inefficiency could indicate a slow metabolism. The apparently strong tongue may have partially reworked and pushed incompletely chewed food into the stomach or possibly a cecum.