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an order of extinct mammals that lived from the Jurassic to the Middle Eocene. The largest Mesozoic mammals, they attained the size of marmots. Multituberculates resembled rodents in that they had a pair of large incisors in both the upper and lower jaws and large molars with numerous tubercles arranged in regular longitudinal rows. Their feeding habits and way of life appear to have been similar to those of rodents that appeared later. The structure of their limbs indicates an arboreal way of life. The animals were probably oviparous, as are present-day prototheres. However, a number of features of their structure show them to be related to marsupials. Multituberculates were distributed in Western Europe, Central Asia, and North America. The order is a unique lateral branch of a class of mammals that left no descendants.