I had never heard growling between these coyotes until today. They are 18 month-old male siblings who appear to be going through the process of separation between each other. They have always played wholeheartedly as buddies until very recently. Here, the dominant guy to the left approached the guy to the right. The less dominant guy to the right narrowed his eyes, put his ears down and growled; he then shook himself out, maybe to reduce tension? Ears down indicates caution and wariness. This ended the interaction, with both then sitting together side by side on the hillside.
I call the less dominant guy “less dominant” and not “submissive” because, although he is the one who moves off or hits the ground when the two interact, he nonetheless snaps or growls in his own defense. His ears are often carried low — down and to the sides — when these two are together: a sign of being cautious and wary.