A new species, Yuomys robustus of the ctenodactyloid rodent Yuomys, is described in the paper. It is from the Western margin of the Ordos Basin District in eastern Ningxia Hui Autonomous Region, China. Yuomys robustus is characterized by a combination of features: large size, high tooth crown, having a postparacrista on M2 and lacking hypocone on P4. We also emended the diagnosis of type species of Yuomys, Y. cavioides. It is characterized by the absence of hypocone on P4, having a distinct ridge connecting the metaconule to the protocone on M1-M3, a postparacrista on M1, a mesostyle on M2, and a small ridge or spur on the mesial side of the protoloph on P4 and M1; the hypoconid smaller than the protoconid and is elongated, the paraconid absent and the mesostylid faintly visible on p4, but well developed on m1-m3; the talonid basin, sinusid, and posteroflexid are large and open on lower cheek teeth. The occurrence of Lophiomeryx angarae in the same stratigraphic layer as Y. robustus indicates that the horizon is possibly late Eocene in age, not early Oligocene as suggested by previous workers. Body mass estimations of Y. cavioides, Y. eleganes, and Y. robustus show that their weights are roughly in the range of 485-880 g, which is in between those of extant Myospalax and Ratufa. From the middle Eocene to the late Eocene, Yuomys exhibited a trend of gradually enlarging the cheek teeth, and increasing the tooth crown height and body mass.

Complete coverage path planning requires that the mobile robot traverse all reachable positions in the environmental map. Aiming at the problems of local optimal path and high path coverage ratio in the complete coverage path planning of the traditional biologically inspired neural network algorithm, a complete coverage path planning algorithm based on Q-learning is proposed. The global environment information is introduced by the reinforcement learning method in the proposed algorithm. In addition, the Q-learning method is used for path planning at the positions where the accessible path points are changed, which optimizes the path planning strategy of the original algorithm near these obstacles. Simulation results show that the algorithm can automatically generate an orderly path in the environmental map, and achieve 100% coverage with a lower path repetition ratio.

Fossil evidence is indispensable for studying the derivation, divergence, and dispersal of squirrels as they responded to global Cenozoic climatic and paleoenvironmental change. Among these fossil records, the earliest known definitive fossil squirrels in Eurasia occur after the Eocene/Oligocene Boundary and are slightly younger than the oldest records in North America. Here, we report the discovery of two new extinct large squirrel species from the late Eocene of the Junggar Basin in northwestern China. The dental morphologies of these new taxa represent tree and flying morphotypes, and their estimated body masses are approximately 1.2 kg and 2.6 kg, respectively. In addition, these extinct lineages push the age of the first appearance of Sciuridae in northern Asia into the late Eocene. Together with Douglassciurus and Oligospermophilus from North America, these two new squirrels from the Junggar Basin are the earliest records of sciurids, and analysis of their teeth clearly demonstrates that the three principle morphotypes of sciurids (flying, ground, and tree squirrels) had diverged from one another by the late Eocene. That proposed late Eocene divergence among the major groupings of sciurids is consistent with some molecular clock analyses and helps to document that macroevolutionary timing and pattern. Comparison with modern squirrel analogs for body masses over 1 kg points to these early Chinese species as having occupied forested habitats, and that hypothesis is congruent with published palynological studies. Furthermore, these two new squirrel taxa from Jeminay provide new data to evaluate the examination of the long-term aridification of Central Asia.