A new arboreal haramiyid shows the diversity of crown mammals in the Jurassic period

摘要

A major unsolved problem in mammalian evolution is the origin of Allotheria, including Multituberculata and Haramiyida~(1-5). Multituber-culates are the most diverse and best known Mesozoic era mammals and ecologically resemble rodents, but haramiyids are known mainly from isolated teeth, hampering our search for their phylogenetic relationships. Here we report a new haramiyid from the Jurassic period of China, which is, to our knowledge the largest reported so far. It has a novel dentition, a mandible resembling advanced multi-tuberculates and postcranial features adapted for arboreal life. Our phylogenetic analysis places Haramiyida within crown Mammalia, suggesting the origin of crown Mammalia in the Late Triassic period and diversification in the Jurassic, which contrasts other estimated divergence times of crown Mammalia~(6-8).