This type of jerboa also boasts some audacious auricles -- almost no other animal has such a large disproportion between ears and body. But this is yet another evolutionary advantage, as the large ears allow for heat to dissipate from jerboa to air, cooling it down faster than a creature of the short-eared persuasion.
Although significantly less aerodynamic.
For perspective, if a human were to have the same proportions, then Yao Ming's ears would be the size of Jada Pinkett Smith (coincidentally, this is the most interesting fact about Jada Pinkett Smith). But the pygmy jerboa variant is the most damning evidence of nature's lazy reuse of animal traits: This unassuming, tiny little creature can jump up to 9 freaking feet. Nature was so lazy, she didn't even bother changing the leap setting. She just spliced a kangaroo's stats into a mouse body, slapped a rabbit head on there, and spent the rest of the day binge-watching Buffy.