Zhenyuanlong suni is a new dromaeosaur just recently described by Steve Brusatte and Lü Junchang and published in Nature's Scientific Reports (it's open-access!). This little fellow was about 6 feet (2 meters) long, about the size of its Velociraptor cousin, and was preserved with amazingly large and modern-looking vaned feathers on its arms and tail. Its wings are remarkably large and clearly show the same arrangement of primaries, secondaries and coverts common to modern birds. Some of these feathers even look somewhat asymmetrical, which in modern birds only exist for flying. So what on earth would a dromaeosaur this large be doing with wings like this, when it obviously couldn't fly?
Nest brooding, RPR, wing-assisted incline running are all possibilities, but the authors speculate that their most likely function was in display or signaling, either in courtship to impress mates, or to intimidate rivals. But all sorts of dinosaurs have been drawn displaying at rivals and females dozens of times, so I wanted to illustrate a somewhat unique idea inspired by my dad's encounter with a cardinal last summer.
This male cardinal would come to the same sliding glass door every day and try to attack his own reflection, beating his wings against the glass, pooping all over the porch and window, and generally being full of testosterone and ire. Glass and mirrors are unnatural and therefore it's not too surprising that an animal could be confused by them, but water? Unlikely, but let me paint the scenario:
This male Zhenyuanlong, when competing for a female, has just been forced to back down by a male with a better display. He's feeling rather out of sorts. Hopping across some rocks in a river, he catches sight of that bright orange crest and those striking high-contrast shocks of black and white in his reflection. On some level he knows it's not real, but seeing them just makes him so damn mad. Next thing he knows he's fuzzed up in full display, seething with rage and crapping all over the place. He'll show that bouncing light who's boss!