This is aggressive coyote behavior. This individual arched his back and displayed is teeth while walking about 100yds towards the location where another coyote was bedded in the open in Lamar Valley, YNP. The second coyote finally rose to his feet and gave ground, and this coyote then sniffed the area and curled up himself in the same location.
The top coyote was driven off his napping spot by the lower coyote. Here they both look northwest toward the sound of a wolf howling in the distance. The lower coyote would then lay down in the napping spot vacated by the upper coyote.