We present surprising observations by the NASA Van Allen Probes spacecraft of whistler waves with substantial electric field power at harmonics of the whistler wave fundamental frequency. The wave power at harmonics is due to a nonlinearly steepened whistler electrostatic field that becomes possible in the two-temperature electron plasma due to the whistler wave coupling to the electron-acoustic mode. The simulation and analytical estimates show that the steepening takes a few tens of milliseconds. The hydrodynamic energy cascade to higher frequencies facilitates efficient energy transfer from cyclotron resonant electrons, driving the whistler waves, to lower energy electrons.

A new genus and species of an amphicyonid from the Bose Basin of Guangxi, south China, is short-jawed with relatively bunodont cheek teeth that are characterized by reduction in cusp number. This taxon is the oldest record of an amphicyonid from south Asia and possibly for all of Asia. Despite its antiquity, it is derived in the development of brachygnathy and differs from other early amphicyonids that have shortened faces. Evidently brachygnathy was established in this species without loss of p1-2 or m2-3, which became single-rooted from a primitive double-rooted condition.