Dual origin of tribosphenic mammals

@article{Luo2001DualOO,
  title={Dual origin of tribosphenic mammals},
  author={Zhe‐Xi Luo and Richard. Cifelli and Zofia Kielan-Jaworowska},
  journal={Nature},
  year={2001},
  volume={409},
  pages={53-57}
}
Marsupials, placentals and their close therian relatives possess complex (tribosphenic) molars that are capable of versatile occlusal functions. This functional complex is widely thought to be a key to the early diversification and evolutionary success of extant therians and their close relatives (tribosphenidans). Long thought to have arisen on northern continents, tribosphenic mammals have recently been reported from southern landmasses. The great age and advanced morphology of these new… 
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