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ABSTRACT
Two eobaatarid multituberculate genera including three species from the Lower Cretaceous (Aptian-Albian) Shahai and Fuxin formations in Liaoning Province, northeastern China are described here: Sinobaatar xiei sp. nov., S. fuxinensis sp. nov., and Liaobaatar changi gen. et sp. nov. Sinobaatar xiei is characterized by m1 with cusp formula 3:2 (labial:lingual), P4 with cusp formula 2:4, blade-like P5 with three cusps anteroposteriorly arranged, M1 with cusp formula 4:4, and M2 with cusp formula 3:4. P1 to P3 of S. xiei lack distinct posterior cingulum. Sinobaatar fuxinensis has a more distinct posterior cingulum on P1 to P3, and its M2 has cusp formula 3:3. Sinobaatar xiei is within the size range of most other eobaatarids, and S. fuxinensis is slightly larger than S. xiei. Liaobaatar changi is clearly larger than other eobaatarids. The ratio of p4 length and height of L. changi and S. xiei (L./S.) are 1.9 and 1.7, respectively. Liaobaatar changi is also characterized by m1 with cusp formula 3:3. A specimen of S. fuxinensis indicates that tooth replacement in eobaatarids occurred in the typical backward sequence seen in Late Cretaceous-Tertiary multituberculates.
