Armadillos include extinct two-tonne glyptodonts
Spanish speakers named them little armored ones—twenty-one living cingulate species native only to the Americas. Genetic work now folds giant Pleistocene glyptodonts, once two tonnes and one and a half metres tall, inside true armadillos closer to most living lineages than to long-nosed Dasypus.
Leathery osteoderm shells and digging claws define the look. Average length is about seventy-five centimetres including the tail; giant armadillos reach one hundred fifty centimetres and fifty-four kilograms, while pink fairy armadillos weigh about eighty-five grams at thirteen to fifteen centimetres. Aztec Nahuatl called them turtle-rabbits; Portuguese tatu comes from Tupi. They share Xenarthra with anteaters and sloths, sporting low body temperatures of thirty-three to thirty-six degrees Celsius and metabolic rates forty to sixty percent of expectations for their mass.
Earliest fossils appear in South America around fifty-two to fifty-five million years ago in the early Eocene; modern groups diverged through that epoch. Eyesight is poor; smell guides foraging. Burrows are single corridors the width of the body. Gestation lasts sixty to one hundred twenty days, and nine-banded armadillos delay implantation so births follow about eight months after mating. Dasypus species typically deliver identical quadruplets.
Unusually for mammals, armadillas can develop systemic leprosy, a trait used in laboratory study because cool bodies suit Mycobacterium leprae. That biomedical footnote sits atop an American radiation that once included car-sized glyptodonts extinct near twelve thousand years ago. Armor, low metabolism, and a New World map still summarise the clan. Xenarthran coolness that welcomes leprosy bacteria in the lab is the same physiology that suits termite specialists in tropical night air. From fairy armadillo sand swimmers to vanished glyptodont tanks, armor has been the family's signature for more than fifty million years.
Source: Armadillo
